JP2006332031A - Light emitting device and its formation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device using an organic luminous layer and a carrier transporting layer made of an organic compound which has a high efficiency and small deterioration of property. <P>SOLUTION: The light emitting device comprises a positive electrode, a negative electrode opposed to the positive electrode, a luminous layer which is installed between the positive electrode and the negative electrode and is made of an organic compound, and a carrier transporting layer made of an organic compound all on a substrate. The luminous layer and the carrier transporting layer are laminated alternately, and the film thickness of the carrier transporting layer is thinner than that of the luminous layer. When the carrier transporting layer is a hole transporting layer, the luminous layer is an electron transporting luminous layer, and when the carrier transporting layer is the electron transporting layer, the luminous layer is the hole transporting luminous layer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting device used for a display or the like and a manufacturing method thereof.

  In recent years, with the advancement of the information society, there is an increasing need for thin displays that consume less power than conventional CRTs. As such a display, there are a liquid crystal display and a plasma display, which have already been put into practical use.

  Recently, development of light-emitting devices using organic compounds has been progressing with the aim of lower power consumption and clearer full color than these displays. In this case, electrodes (anode and cathode) are attached to both surfaces of a solid thin film of an organic compound that emits strong fluorescence or phosphorescence in a solid state. Then, holes are injected from the anode, electrons are injected from the cathode, and the holes and electrons are recombined in the organic compound to create an excited state of the organic compound, and the excited state returns to the ground state. Sometimes it emits light of the same wavelength as the fluorescence or phosphorescence of the organic compound.

  The structure of the light-emitting device can be a single-layer structure in which three roles of hole movement, electron movement, and hole-electron recombination are assigned to a single organic compound layer, or three roles are dispersed. A two-layer structure or a three-layer structure has been reported. Examples thereof include those in which a hole transport layer, a light emitting layer, and an electron transport layer are formed.

However, the reported light-emitting device has a problem that its luminous efficiency is low and it cannot be put into practical use. In order to solve this problem, Patent Document 1 provides a light emitting device having a superlattice structure in which organic light emitting layers and inorganic compounds are alternately stacked.
JP-A-8-102360

  Since the thing of patent document 1 is what laminated | stacked the organic light emitting layer and the inorganic compound alternately, there exists a possibility that a characteristic may deteriorate by stress.

  Accordingly, an object of the present invention is to provide a light-emitting device with high efficiency and less characteristic deterioration by a multi-layered structure using an organic light-emitting layer and a carrier transport layer made of an organic compound.

The present invention is a light emitting device having a structure in which a light emitting layer made of an organic compound and a carrier transport layer made of an organic compound are alternately stacked. An electrode,..., A light emitting layer, a carrier transport layer, a light emitting layer, a carrier transport layer, a light emitting layer, a carrier transport layer,. In addition, the carrier transport layer and the light emitting layer can be alternately laminated in 2 to n (n is a positive integer) layer. For example, the following can be mentioned.
(1) Anode, hole transport layer, light emitting layer, hole transport layer, light emitting layer, hole transport layer, light emitting layer, hole transport layer, ..., light emitting layer, electron transport layer, cathode (2) anode , First hole transport layer, light emitting layer, second hole transport layer, light emitting layer, second hole transport layer, light emitting layer, second hole transport layer,..., Light emitting layer, electron Transport layer, cathode (3) anode, hole transport layer, light emitting layer, electron transport layer, light emitting layer, electron transport layer, light emitting layer, electron transport layer, ..., light emitting layer, electron transport layer, cathode (4) Anode, hole transport layer, light emitting layer, second electron transport layer, light emitting layer, second electron transport layer, light emitting layer, second electron transport layer,..., Light emitting layer, first electron transport layer As the configuration in the vicinity of the anode, (a) an anode, a hole injection layer, a hole transport layer, (a) an anode, a hole injection layer, and a first hole transport layer can be used. The vicinity of the cathode may be configured as (c) an electron transport layer, an electron injection layer, a cathode, and (d) a first electron transport layer, an electron injection layer, and a cathode. In the above (2), when the first hole transport layer and the second hole transport layer are the same material, the structure of (1) is obtained. In (4), when the first electron transport layer and the second electron transport layer are made of the same material, the configuration (3) is obtained.

  In the present invention, the carrier transport layer may be either a hole transport layer or an electron transport layer. However, when the light emitting layer has an electron transport property, the carrier transport layer becomes a hole transport layer. On the contrary, when the light emitting layer has a hole transporting property, the carrier transporting layer becomes an electron transporting layer.

  In addition, the present invention is a light emitting device in which the thickness of the carrier transport layer is thinner than that of the light emitting layer. The thickness of the carrier transport layer is preferably 1 nm to 5 nm, and the thickness of the light emitting layer is preferably 5 nm to 20 nm. This enables carrier movement based on the tunnel effect.

  In the present invention, when the carrier transport layer is a hole transport layer (that is, the configuration of (1) above), the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is the LUMO level of the hole transport layer. Is larger than the absolute value of the energy difference from the vacuum level (the LUMO level of the light emitting layer is lower than the LUMO level of the hole transport layer), and the energy difference from the vacuum level of the HOMO level of the light emitting layer The absolute value of is preferably larger than the absolute value of the energy difference from the vacuum level of the HOMO level of the hole transport layer (the HOMO level of the light-emitting layer is lower than the HOMO level of the hole transport layer). Note that LUMO is Lowest Unoccupied Molecular Orbital, the lowest unoccupied molecular orbital, and HOMO is Highest Occupied Molecular Orbital, the highest occupied molecular orbital.

  On the other hand, when the carrier transport layer is an electron transport layer (that is, the configuration of (3) above), the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is the vacuum level of the LUMO level of the electron transport layer. The absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is smaller than the absolute value of the energy difference from the level (the LUMO level of the light emitting layer is higher than the LUMO level of the electron transport layer). The absolute value of the energy difference from the vacuum level of the HOMO level of the transport layer is preferably smaller (the HOMO level of the light-emitting layer is higher than the HOMO level of the electron transport layer).

  In the case of the above configuration (2), the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is the absolute value of the energy difference from the vacuum level of the LUMO level of the second hole transport layer. (The LUMO level of the light emitting layer is lower than the LUMO level of the second hole transport layer), and the absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is the second positive value. It is preferable that the absolute value of the energy difference from the vacuum level of the HOMO level of the hole transport layer is larger (the HOMO level of the light-emitting layer is lower than the HOMO level of the second hole transport layer).

  The absolute value of the energy difference between the HOMO level of the first hole transporting layer and the HOMO level of the light emitting layer is the energy difference between the HOMO level of the second hole transporting layer and the HOMO level of the light emitting layer. Is preferably smaller than the absolute value of.

  The absolute value of the energy difference between the work function of the anode and the HOMO level of the first hole transport layer is the absolute value of the energy difference between the HOMO level of the second hole transport layer and the HOMO level of the light emitting layer. Preferably it is smaller than the value.

  In the case of the configuration (4), the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is greater than the absolute value of the energy difference from the vacuum level of the LUMO level of the second electron transport layer. (The LUMO level of the light emitting layer is higher than the LUMO level of the second electron transport layer), and the absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is the second electron transport layer. It is preferable that the absolute value of the energy difference from the vacuum level of the HOMO level is smaller (the HOMO level of the light emitting layer is higher than the HOMO level of the second electron transport layer).

  The absolute value of the energy difference between the LUMO level of the first electron transporting layer and the LUMO level of the light emitting layer is the absolute value of the energy difference between the LUMO level of the second electron transporting layer and the LUMO level of the light emitting layer. Preferably it is smaller than the value.

  The absolute value of the energy difference between the work function of the cathode and the LUMO level of the first electron transport layer is the absolute value of the energy difference between the LUMO level of the second electron transport layer and the LUMO level of the light emitting layer. Is preferably smaller.

  In the present invention, a light-emitting material made of an organic compound and a carrier transport material made of an organic compound can be co-evaporated to produce the material. In manufacturing the above multi-layered structure, a shutter and a mask are provided, and the film thickness of the light emitting layer and the carrier transport layer can be controlled by opening and closing the shutter and the mask.

  For example, a shutter or mask is provided between the evaporation source of the light emitting material and the substrate that is the deposition target, and between the evaporation source of the carrier transport material and the substrate that is the deposition target, and the film thickness is controlled by opening and closing the shutter and mask. To do. It is deposited on the substrate when the shutter is open or not masked, and is not deposited on the substrate when the shutter is closed or masked.

When the light-emitting material evaporation source shutter or mask is open and the light-emitting material is deposited on the substrate, the carrier transport material evaporation source shutter or mask is closed so that it is not deposited on the substrate. Next, the shutter or mask on the evaporation source of the luminescent material is closed so that it is not deposited on the substrate, and the shutter or mask on the evaporation source of the carrier transport material is opened to deposit the carrier transport material on the substrate. Thereby, a light emitting layer and a carrier transport layer can be laminated | stacked alternately.
However, in the present invention, since the thickness of the carrier transport layer needs to be smaller than the thickness of the light emitting layer, it is necessary to control the opening and closing time of the shutter and mask.

  The mask may be opened and closed by rotation. Further, a hole or a slit may be provided in a part of the mask.

  The film thickness can be changed by changing the deposition rate from the evaporation source as the shutter and mask are opened and closed. When the deposition rate is low, the film thickness becomes thin if the time during which the shutter and the mask are open is short. Conversely, if the deposition rate is increased and the time during which the shutter and the mask are opened is long, the film thickness increases.

  The substrate which is the deposition object may be rotated (so-called rotation). By rotating the substrate, the uniformity of the in-plane distribution of film thickness can be improved.

  In addition, it is possible to change the deposition amount by fixing the evaporation source containing the light emitting material and the evaporation source containing the carrier transporting material apart from each other and rotating (so-called revolution) while moving the substrate. . Further, the substrate may be rotated by combining rotation and revolution.

  For example, the substrate is provided on the first rotating plate, the first rotating plate is provided on the evaporation source of the light emitting material and the evaporation source of the carrier transporting material, and the first rotating plate rotates to By changing the distance between the substrate and the distance between the evaporation source of the carrier transport material and the substrate, the light emitting layer and the carrier transport layer are alternately stacked.

When the first rotating plate rotates, the distance between the evaporation source of the light emitting material and the substrate and the distance between the evaporation source of the carrier transport material and the substrate change. When the distance between the evaporation source of the light emitting material and the substrate is short, more light emitting material is deposited on the substrate to form a light emitting layer. On the other hand, when the distance between the evaporation source of the carrier transport material and the substrate is short, more carrier transport material is deposited on the substrate to form a carrier transport layer. Thus, by rotating the first rotating plate and changing the position of the substrate with respect to the evaporation source, the light emitting layer and the carrier transport layer can be alternately stacked, and a multi-layered structure can be realized.
Although the substrate is moved here, the substrate may be fixed and the evaporation source of the light emitting material and the evaporation source of the carrier transport material may be moved.

  However, in the present invention, the thickness of the carrier transport layer needs to be smaller than the thickness of the light emitting layer. Therefore, the opening / closing time may be controlled by controlling the deposition rate from the evaporation source, or providing a shutter or mask between the carrier transport material and the substrate.

  A second rotating plate having a central axis different from that of the first rotating plate and rotating independently may be provided on the first rotating plate, and the substrate may be provided on the second rotating plate. The film thickness uniformity in the substrate surface may be improved by rotating the second rotating plate (so-called substrate rotation).

  In the present invention, a buffer layer made of an organic compound and a metal compound may be provided between the electrode and the carrier transport layer. Thereby, flatness can be improved. (E) anode, buffer layer, hole transport layer, (f) anode, buffer layer, first hole transport layer, (g) electron transport layer, buffer layer, cathode, (g) first electron transport A layer, a buffer layer, and a cathode may be used. In this case, a hole injection layer and an electron injection layer may be provided as described above.

  The present invention comprises, on a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a hole transport layer made of an organic compound, and the light emission The layer and the hole transport layer are alternately laminated, the film thickness of the hole transport layer is smaller than the film thickness of the light emitting layer, and the light emitting layer is an electron transporting light emitting layer.

  The light emitting layer and the hole transport layer are alternately laminated in a range of 2 to n (n is a positive integer).

  The hole transport layer has a thickness of 1 nm to 5 nm, and the light emitting layer has a thickness of 5 nm to 20 nm.

  The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is larger than the absolute value of the energy difference from the vacuum level of the LUMO level of the hole transport layer, and the HOMO level of the light emitting layer. The absolute value of the energy difference from the vacuum level of the position is larger than the absolute value of the energy difference from the vacuum level of the HOMO level of the hole transport layer.

  The LUMO level of the light emitting layer is lower than the LUMO level of the hole transport layer, and the HOMO level of the light emitting layer is lower than the HOMO level of the hole transport layer.

  The present invention comprises, on a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and an electron transport layer made of an organic compound, The layer and the electron transport layer are alternately laminated, the film thickness of the electron transport layer is thinner than the film thickness of the light emitting layer, and the light emitting layer is a hole transporting light emitting layer.

  The light emitting layer and the electron transport layer are alternately laminated in a range of 2 to n (n is a positive integer).

  The electron transport layer has a thickness of 1 nm to 5 nm, and the light emitting layer has a thickness of 5 nm to 20 nm.

  The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is smaller than the absolute value of the energy difference from the vacuum level of the LUMO level of the electron transport layer, and the HOMO level of the light emitting layer. The absolute value of the energy difference from the vacuum level is smaller than the absolute value of the energy difference from the vacuum level of the HOMO level of the electron transport layer.

  The LUMO level of the light emitting layer is higher than the LUMO level of the electron transport layer, and the HOMO level of the light emitting layer is higher than the HOMO level of the electron transport layer.

  A buffer layer made of an organic compound and a metal compound may be provided in contact with the anode.

  The present invention provides a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, a first hole transport layer made of an organic compound, an organic A second hole transport layer made of a compound, the light emitting layer is an electron transporting light emitting layer, and a first hole transport layer made of an organic compound is formed on the anode, and the first positive transport layer is made of A light emitting layer made of an organic compound and a second hole transport layer made of an organic compound are alternately stacked on the hole transport layer, and the film thickness of the second hole transport layer is larger than the film thickness of the light emitting layer. Is also thin.

  The light emitting layer and the second hole transport layer are alternately laminated in a range of 2 to n (n is a positive integer).

  The film thickness of the second hole transport layer is 1 nm or more and 5 nm or less, and the film thickness of the light emitting layer is 5 nm or more and 20 nm or less.

  The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is larger than the absolute value of the energy difference from the vacuum level of the LUMO level of the second hole transport layer, The absolute value of the energy difference from the vacuum level of the HOMO level is greater than the absolute value of the energy difference from the vacuum level of the HOMO level of the second hole transport layer.

  The LUMO level of the light emitting layer is lower than the LUMO level of the second hole transport layer, and the HOMO level of the light emitting layer is lower than the HOMO level of the second hole transport layer.

  The absolute value of the energy difference between the HOMO level of the first hole transport layer and the HOMO level of the light emitting layer is determined by calculating the HOMO level of the second hole transport layer and the HOMO level of the light emitting layer. It may be smaller than the absolute value of the energy difference from the position.

  The absolute value of the energy difference between the work function of the anode and the HOMO level of the first hole transport layer is the HOMO level of the second hole transport layer and the HOMO level of the light emitting layer. It may be smaller than the absolute value of the energy difference.

  A buffer layer made of an organic compound and a metal compound may be provided between the first hole transport layer and the anode.

  The present invention provides a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, a first electron transport layer made of an organic compound, an organic compound A light-emitting layer made of an organic compound and a second electron-transport layer made of an organic compound are alternately stacked, and the organic compound is formed on the stacked layer. The first electron transport layer is formed, the cathode is formed on the first electron transport layer, and the film thickness of the second electron transport layer is smaller than the film thickness of the light emitting layer.

  The light emitting layer and the second electron transporting layer are alternately laminated in an amount of 2 to n (n is a positive integer).

  The film thickness of the second electron transport layer is 1 nm or more and 5 nm or less, and the film thickness of the light emitting layer is 5 nm or more and 20 nm or less.

  The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer is smaller than the absolute value of the energy difference from the vacuum level of the LUMO level of the second electron transport layer. The absolute value of the energy difference from the vacuum level of the HOMO level is smaller than the absolute value of the energy difference from the vacuum level of the HOMO level of the second hole transport layer.

  The LUMO level of the light emitting layer is higher than the LUMO level of the second electron transport layer, and the HOMO level of the light emitting layer is higher than the HOMO level of the second hole transport layer.

  The absolute value of the energy difference between the HOMO level of the first electron transporting layer and the HOMO level of the light emitting layer is expressed by the HOMO level of the second electron transporting layer and the HOMO level of the light emitting layer. It may be smaller than the absolute value of the energy difference.

  The absolute value of the energy difference between the work function of the cathode and the HOMO level of the first electron transport layer is the energy difference between the HOMO level of the second electron transport layer and the HOMO level of the light emitting layer. It may be smaller than the absolute value of.

  A buffer layer made of an organic compound and a metal compound may be provided between the first electron transport layer and the cathode.

  The present invention comprises, on a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a carrier transport layer made of an organic compound, Layer and the carrier transport layer are alternately laminated, and the thickness of the carrier transport layer is a manufacturing method of a light emitting device thinner than the thickness of the light emitting layer, and the evaporation source of the carrier transport material and the light emitting material The substrate is provided on the evaporation source, and a first shutter that can be opened and closed is provided between the evaporation source of the carrier transporting material and the substrate, and is provided between the evaporation source of the light emitting material and the substrate. And a second shutter that can be opened and closed, and the light emitting layer and the carrier transport layer are alternately stacked by opening and closing the first and second shutters.

  When the first shutter is open, the second shutter is closed to deposit the carrier transport material on the substrate, and when the second shutter is open, the first shutter is closed to A light emitting material is deposited on the substrate, and the light emitting layer and the carrier transport layer are alternately stacked.

  The light emitting layer and the carrier transport layer may be alternately stacked by controlling the opening and closing of the first and second shutters, the deposition speed of the light emitting material, and the deposition speed of the carrier transport material.

  The present invention comprises, on a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a carrier transport layer made of an organic compound, Layers and the carrier transport layer are alternately laminated, and the thickness of the carrier transport layer is a manufacturing method of a light emitting device thinner than the thickness of the light emitting layer, and the substrate is formed on a first rotating plate. The first rotating plate is provided on the evaporation source of the light emitting material and the evaporation source of the carrier transport material, and the first rotating plate rotates to rotate the evaporation source of the light emitting material and the substrate. , And the distance between the evaporation source of the carrier transport material and the substrate, the light emitting layer and the carrier transport layer are alternately stacked.

  When the first rotating plate rotates and the distance between the evaporation source of the light emitting material and the substrate is shorter than the distance between the evaporation source of the carrier transport material and the substrate, the light emitting material is transported by the carrier. When the light emitting layer is formed by vapor deposition more than the material, and the distance between the evaporation source of the carrier transport material and the substrate is shorter than the distance between the evaporation source of the light emission material and the substrate, the carrier transport material Is deposited more than the light emitting material to form the carrier transport layer.

  The light emitting layer and the carrier transport layer may be alternately stacked by controlling the deposition rate of the light emitting material and the deposition rate of the carrier transport material.

  A shutter that can be opened and closed is provided between the carrier transport layer and the substrate, and controls the rotation of the first rotating plate and controls the opening and closing of the shutter to alternately switch the light emitting layer and the carrier transport layer. May be laminated.

  A second rotating plate is provided on the first rotating plate, the substrate is provided on the second rotating plate, and a central axis different from the first rotating plate and the second rotating plate. And may be rotated independently of each other.

  The present invention comprises, on a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a carrier transport layer made of an organic compound, Layer and the carrier transport layer are alternately laminated, and the thickness of the carrier transport layer is a manufacturing method of a light emitting device thinner than the thickness of the light emitting layer, and the evaporation source of the carrier transport material and the light emitting material The substrate is provided on the evaporation source, and a rotatable first mask is provided between the evaporation source of the light emitting material and the substrate, and between the evaporation source of the carrier transport material and the substrate. A rotatable second mask is provided, and the light emitting layer and the carrier transport layer are alternately stacked by controlling rotation of the first and second masks.

  The first and second masks may be provided with slits or holes.

  When the hole or slit of the first mask is between the evaporation source of the luminescent material and the substrate, the hole or slit of the second mask exists between the carrier transport material and the substrate. Without depositing the luminescent material on the substrate, and when the hole or slit of the second mask is between the evaporation source of the carrier transport material and the substrate, the hole or The carrier transport material may be deposited on the substrate without causing a slit to exist between the light emitting material and the substrate, and the light emitting layer and the carrier transport layer may be alternately stacked.

  The light emitting layer and the carrier transport layer may be alternately stacked by controlling the deposition rate of the light emitting material and the deposition rate of the carrier transport material.

  The present invention has a structure in which a light emitting layer made of an organic compound and a carrier transport layer made of an organic compound are alternately laminated, and is not a multilayer laminated structure of an inorganic compound. A light emitting device with high luminous efficiency can be obtained.

  In the present invention, the light emitting layer and the carrier transporting layer have different polarities, and the thickness of the carrier transporting layer is smaller than that of the light emitting layer, and the light emitting layer having the LUMO level and the HOMO level as described above, the carrier transporting layer. Have As a result, carriers having the same polarity as the carrier transport layer are easily confined, and carriers having different polarities move by the tunnel effect. That is, one carrier can be confined, and the luminous efficiency can be increased.

  Further, by providing a buffer layer made of an organic compound and a metal compound between the electrode and the carrier transport layer, the flatness can be improved even if the substrate has irregularities. The thickness of the buffer layer may be 60 nm or more. In the case of the present invention, even if the thickness of the buffer layer is increased, the drive voltage is not increased.

  By implementing the above manufacturing method, a multi-layer structure can be manufactured. Further, a light-emitting device that can easily control the film thickness, has little characteristic deterioration, and has high emission efficiency can be obtained.

(Embodiment 1)
One embodiment of the present invention will be described with reference to FIGS. Here, the case where the carrier transport layer is a hole transport layer will be described.

1 includes an anode 2, a first hole transport layer 3, a light emitting layer 4, a second hole transport layer 5, a light emitting layer 4, a second hole transport layer 5, on a substrate 1. The second hole transport layer 5, the light emitting layer 4, the electron transport layer 6, and the cathode 7 are formed. A hole injection layer may be provided between the anode 2 and the first hole transport layer 3. An electron injection layer may be provided between the cathode 7 and the electron transport layer 6. The same material may be used for the first hole transport layer and the second hole transport layer, or different materials may be used.
The second hole transport layer 5 and the light emitting layer 4 are laminated in multiple layers. The film thickness of the second hole transport layer 5 is thinner than that of the light emitting layer 4, the film thickness of the second hole transport layer is preferably 1 nm or more and 5 nm or less, and the film thickness of the light emitting layer is preferably 5 nm or more and 20 nm or less. The light emitting layer 4 is electron transporting.
In addition, the second hole transport layer 5 and the light emitting layer 4 can be alternately laminated by 2 to n (n is a positive integer) layer.

Here, the energy level, carrier movement, etc. of the present invention will be described with reference to FIGS. 3 and 4 show band diagrams of the configuration of FIG. FIG. 4 shows a band diagram of the light emitting layer 4 and the hole transport layer 5 that are stacked in multiple layers.
The reference numerals are the same as those in FIG. Reference numeral 50 denotes a vacuum level, and 51 denotes an absolute value of an energy difference from the vacuum level 50 of the LUMO level of the first hole transport layer 3. 52 indicates the absolute value of the energy difference from the vacuum level 50 of the HOMO level of the first hole transport layer 3.
53 represents the absolute value of the energy difference from the vacuum level 50 of the LUMO level of the second hole transport layer 5, and 54 represents the vacuum level 50 of the HOMO level of the second hole transport layer 5 from the vacuum level 50. Indicates the absolute value of the energy difference. 55 represents the absolute value of the energy difference from the vacuum level 50 of the LUMO level of the light emitting layer 4, and 56 represents the absolute value of the energy difference from the vacuum level 50 of the HOMO level of the light emitting layer 4.

  In the present invention, the absolute value 55 of the energy difference from the vacuum level of the LUMO level of the light emitting layer 4 is larger than the absolute value 53 of the energy difference from the vacuum level of the LUMO level of the second hole transport layer 5. Large (the LUMO level of the light emitting layer 4 is lower than the LUMO level of the second hole transport layer 5). The absolute value 56 of the energy difference from the vacuum level of the HOMO level of the light emitting layer 4 is larger than the absolute value 54 of the energy difference from the vacuum level of the HOMO level of the second hole transport layer 5 ( The HOMO level of the light emitting layer 4 is lower than the HOMO level of the second hole transport layer 5).

When a positive potential is applied to the anode 2 and a negative potential is applied to the cathode 7, holes (h ⁺ ) are injected from the anode 2 into the hole transport layer 3, while electrons (e ⁻ ) are transported from the cathode 7. Implanted into layer 6.
The holes are transported from the first hole transport layer to the light emitting layer 4 and recombined with the electrons transported from the cathode in the light emitting layer 4 to emit light. Since the light emitting layer 4 has an electron transport property, the probability that holes recombine with electrons is high. In the drawing, hν is indicated when light is emitted.

  Holes that have not recombined with electrons in the light emitting layer 4 move toward the cathode due to the potential difference. Next, it is injected into the second hole transport layer 5 and moves in the second hole transport layer 5. However, because of the barrier from the second hole transport layer to the light-emitting layer 4 (energy difference 58: energy difference between the HOMO level of the light-emitting layer 4 and the HOMO level of the second hole-transport layer 5), it is positive. The probability that the holes are injected into the light emitting layer 4 is reduced and confined. Even if holes are injected into the light emitting layer 4 through the accumulation of holes or the like, they recombine with electrons in the light emitting layer 4 to emit light. Moreover, even if it is injected into the second hole transport layer 5 without being recombined in the light emitting layer 4, there is a high probability that it is confined due to the barrier to the light emitting layer 4 as described above. Therefore, the penetration into the electron transport layer 6 can be reduced and the luminous efficiency can be increased. In the case where the electron transport layer 6 is luminescent, when holes are injected into the electron transport layer 6, they recombine with electrons and emit light. If the emission wavelengths of the electron transport layer 6 and the light emitting layer 4 are different, a color shift occurs.

  On the other hand, electrons that have not recombined with holes in the light emitting layer 4 move toward the anode due to a potential difference. Here, since the thickness of the second hole transport layer 5 is as thin as 1 nm or more and 5 nm or less, the barrier (energy difference 60: the LUMO level of the light emitting layer 4 and the LUMO level of the second hole transport layer 5). The energy penetrates the light emitting layer 4 and is injected into the next light emitting layer 4. The light emitting layer 4 recombines with holes to emit light. Further, even if it is not recombined in the light emitting layer 4, it is injected from the second hole transport layer 5 to the next light emitting layer 4.

  When the first hole transport layer 3 and the second hole transport layer 5 are different materials, the HOMO level of the first hole transport layer 3 and the light emitting layer 4 are increased in order to increase the hole confinement effect. The absolute value of the energy difference 57 with respect to the HOMO level is preferably smaller than the absolute value of the energy difference 58. Thereby, the probability that the holes injected from the anode 2 cannot exceed the energy difference 58 can be increased.

Further, when the energy difference 59 between the work function of the anode 2 and the HOMO level of the first hole transport layer 3 or the potential applied to the anode and the cathode is controlled, the probability that the holes cannot exceed the energy difference 58. Can be further enhanced.
The energy difference 59 is made smaller than the energy difference 58, and a voltage that exceeds the energy difference 59 is applied. Then, holes can exceed the energy difference 59, but the probability of exceeding the energy difference 58 decreases. Therefore, it is preferable to use the anode 2, the first hole transport layer, the light emitting layer 4, and the second hole transport layer having the above relationship, and further control the voltage applied to the anode and the cathode.

Hereinafter, materials and the like that can be used for each layer will be described.
The substrate 1 is used as a support for the light emitting element. As a material of the substrate 1, for example, quartz, glass, plastic, or the like can be used. Note that other materials may be used as long as the light-emitting element functions as a support in the manufacturing process.

  As the anode 2, indium tin oxide (ITO, Indium Tin Oxide) or the like can be used. Indium zinc oxide (IZO), indium tin oxide containing silicon oxide (ITSO), or the like can also be used. In addition, it is preferably formed of a material having a high work function.

  The first hole transport layer 3 includes 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (abbreviation: NPB or αNPD), 4,4 ′, 4 ′. '-Tris (N-carbazolyl) triphenylamine (abbreviation: TCTA) and the like can be used. The HOMO level is preferably -5.3 eV to -5.6 eV.

The first hole transport layer 3 and the second hole transport layer 5 may be the same material. However, in order to increase the confinement effect of holes, the energy difference between the HOMO level of the first hole transport layer 3 and the HOMO level of the light emitting layer 4 is determined from the HOMO level of the second hole transport layer 5. You may make it smaller than the energy difference with the energy difference of the HOMO level of the light emitting layer 4. FIG. A HOMO level of −4.9 eV to −5.3 eV is preferable, and 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenyl-amino] -triphenylamine (abbreviation) : MTDATA), 4,4′-bis (N- (4- (N, N-di-m-tolylamino) phenyl) -N-phenylamino) biphenyl (abbreviation: DNTPD), 4,4 ′, 4 ″ -Tris [N- (1-naphthyl) -N-phenyl-amino] -triphenylamine (abbreviation: 1-TNATA) or the like can be used.
For example, when the light-emitting layer 4 is made of tris (8-quinolinolato) aluminum (abbreviation: Alq ₃ ) described later and αNPD is used for the first hole transport layer 3, the second hole transport layer has the above relationship. MTDATA with can be used.

Next, regarding the light emitting layer 4, the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer 4 is the energy difference from the vacuum level of the LUMO level of the second hole transport layer 5. It is necessary to make it larger than the absolute value. The absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer 4 needs to be larger than the absolute value of the energy difference from the vacuum level of the HOMO level of the second hole transport layer 5. is there. As a result, holes can be confined as described above, and luminous efficiency can be increased. Further, penetration of holes into the electron transport layer 6 can be prevented.
On the other hand, the film thickness of the second hole transport layer 5 is thinner than that of the light emitting layer 4, the film thickness of the second hole transport layer is 1 nm or more and 5 nm or less, and the film thickness of the light emitting layer is 5 nm or more and 20 nm or less. Therefore, even if it has the above-mentioned energy relationship, electrons penetrate the second hole transport layer 5 and are injected into the light emitting layer 4.
The light-emitting layer 4 can be formed using an electron transporting material such as Alq ₃ in addition to a carbazole derivative such as 4,4′-di (N-carbazolyl) biphenyl (abbreviation: CBP). The HOMO level is preferably -5.5 eV to -5.9 eV.

The light emitting layer 4 may be a host-guest type layer in which a light emitting material is dispersed in a layer made of a material (host material) having an energy gap larger than that of a light emitting substance (dopant material) serving as a light emission center. This is a preferable configuration because concentration quenching hardly occurs. As a light-emitting substance serving as a luminescent center, 4-dicyanomethylene-2-methyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (abbreviation: DCJT), 4 -Dicyanomethylene-2-t-butyl-6- (1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran, perifrantene, 2,5-dicyano-1,4-bis ( 10-methoxy-1,1,7,7-tetramethyljulolidyl-9-enyl) benzene, N, N′-dimethylquinacridone (abbreviation: DMQd), coumarin 6, coumarin 545T, Alq ₃ , 9, 9 ′ -Bianthryl, 9,10-diphenylanthracene (abbreviation: DPA), 9,10-bis (2-naphthyl) anthracene (abbreviation: DNA), 2,5,8,11-tetra-t-butylperylene (Abbreviation: TBP). As described above, in addition to a substance that emits fluorescence, bis [2- (3,5-bis (trifluoromethyl) phenyl) pyridinato-N, C ^{2 ′} ] iridium (III) picolinate (abbreviation: Ir (CF ₃ ppy) 2 (pic)), bis [2- (4,6-difluorophenyl) pyridinato-N, C2 ^' ] iridium (III) acetylacetonate (abbreviation: FIr (acac)), bis [2- (4 , 6-difluorophenyl) pyridinato-N, C2 ^′ ] iridium (III) picolinate (FIr (pic)), tris (2-phenylpyridinato-N, C2 ^′ ) iridium (abbreviation: Ir (ppy) ₃ A substance that emits phosphorescence such as) can also be used as a dopant material.

There is no particular limitation on a substance used for bringing the light-emitting substance into a dispersed state, and a substance having an electron transport property such as a metal complex or Alq ₃ can be used in addition to a carbazole derivative such as CBP.

For example, those having the above energy difference relationship include ITO for the anode 2, αNPD for the first hole transport layer 3, Alq ₃ for the light emitting layer 4, and MTDATA for the second hole transport layer 5. . Of course, it is not limited to this combination.

The electron transport layer 6 is composed of Alq ₃ , bis (2-methyl-8-quinolinolato) -4-phenylphenolato-aluminum (abbreviation: BAlq ₃ ), bathocuproine (abbreviation: BCP), tris (4-methyl-8-quinolinolato). Aluminum (abbreviation: Almq ₃ ) or the like can be used. A HOMO level of −5.5 eV to −6.0 eV is preferable.

  As a material for forming the cathode 7, a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function (work function of −3.8 eV or less) can be used. Specific examples of such a cathode material include elements belonging to Group 1 or Group 2 of the periodic table of elements, that is, alkali metals such as lithium (Li) and cesium (Cs), and magnesium (Mg), calcium (Ca), Examples thereof include alkaline earth metals such as strontium (Sr) and alloys containing them (Mg: Ag, Al: Li). However, by providing a layer excellent in the function of injecting electrons between the cathode 7 and the light-emitting layer by stacking with the cathode, it includes Al, Ag, ITO, and silicon regardless of the work function. Various conductive materials can be used as the cathode 7 including the materials mentioned as the material of the anode 2 such as ITO.

In the case where an electron injection layer is provided between the cathode 7 and the electron transport layer 6, an alkali metal such as lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ ), or the like is used. Earth metal compounds can be used. In addition, a layer made of a substance having an electron transporting property containing an alkali metal or an alkaline earth metal, for example, a layer containing magnesium (Mg) in Alq ₃ can be used.

  Further, as shown in FIG. 2, a buffer layer 8 may be provided between the anode 2 and the first hole transport layer. The buffer layer 8 may be a mixture of an organic compound and a metal compound.

As a combination of an organic compound and a metal compound, 4,4′-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (abbreviation: NPB or αNPD) or 4,4 ′ is used as the organic compound. -Bis [N- (3-methylphenyl) -N-phenyl-amino] -biphenyl (abbreviation: TPD) or 4,4 ′, 4 ″ -tris (N, N-diphenyl-amino) -triphenylamine ( Abbreviation: TDATA), 4,4 ′, 4 ″ -tris [N- (3-methylphenyl) -N-phenyl-amino] -triphenylamine (abbreviation: MTDATA) and 4,4′-bis (N— (4- (N, N-di-m-tolylamino) phenyl) -N-phenylamino) biphenyl (abbreviation: DNTPD), N, N′-bis (spiro-9,9′-bifluoren-2-yl)- N, N'-diphenyl Ndidine (abbreviation: BSPB), 4,4 ′, 4 ″ -tris [3-methylphenyl (phenyl) amino] triphenylamine (abbreviation: m-MTDATA), 1,3,5-tris [N, N— Bis (3-methylphenyl) -amino] -benzene (abbreviation: m-MTDAB), N, N′-di (p-tolyl) -N, N′-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), etc. An aromatic amine-based compound (that is, a benzene ring-nitrogen bond) or a phthalocyanine compound such as phthalocyanine (abbreviation: H ₂ Pc), copper phthalocyanine (abbreviation: CuPc), or vanadyl phthalocyanine (abbreviation: VOPc) is used. Can do.

As the metal compound, transition metal oxides are preferable. Specifically, titanium oxide, zirconium oxide, hafnium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, rhenium oxide, and the like. Is mentioned. In particular, vanadium oxide, molybdenum oxide, tungsten oxide, and rhenium oxide are preferable because of their high electron-accepting properties. Among these, molybdenum oxide is particularly preferable because it is stable in the air and easy to handle.
The metal compound is desirably contained in the range of 5 wt% or more and 80 wt% or less, more preferably 10 wt% or more and 50 wt% or less with respect to the organic compound. The thickness of the buffer layer may be 60 nm or more. In the case of the present invention, even if the thickness of the buffer layer is increased, the drive voltage is not increased.

  The first hole transport layer 3, the light emitting layer 4, the second hole transport layer 5, and the electron transport layer 6 can be formed by an evaporation method. The buffer layer 8 can be formed by co-evaporation of an organic compound and a metal compound. The anode and cathode can be formed by a known sputtering method or vapor deposition method. The hole injection layer and the electron injection layer can also be formed by a known vapor deposition method or the like. Moreover, the light emitting layer 4 and the 2nd hole transport layer 5 can be produced by the method mentioned later.

  Here, a method for measuring the HOMO level and the LUMO level will be described. The HOMO level can be obtained by forming a thin film of the object to be measured on a glass substrate or the like and then measuring it by atmospheric photoelectron spectroscopy (manufactured by Riken Keiki Co., Ltd., AC-2).

  Next, the LUMO level will be described. The absorption spectrum of the object to be measured is measured, and the data is used to determine the absorption edge from the Tauc plot. Then, the absorption edge is estimated as an optical energy gap, and the energy gap between the HOMO level and the LUMO level is calculated. Thereafter, the LUMO level is calculated using the HOMO level and energy gap obtained by photoelectron spectroscopy in the atmosphere.

  For example, when the HOMO level in a thin film state obtained by photoelectron spectroscopy in the atmosphere is −5.28 eV and the energy gap estimated from the absorption spectrum of the thin film is 2.98 eV, the LUMO level is −2.30 eV. It becomes. Needless to say, this method is applicable not only to this embodiment but also to other embodiments.

(Embodiment 2)
One embodiment of the present invention will be described with reference to FIGS. Here, the case where the carrier transport layer is an electron transport layer will be described.

The light-emitting device of FIG. 1 has an anode 2, a hole transport layer 3, a light-emitting layer 4, a second electron transport layer 5, a light-emitting layer 4, a second electron transport layer 5,. The electron transport layer 5, the light emitting layer 4, the first electron transport layer 6, and the cathode 7 are formed. A hole injection layer may be provided between the anode 2 and the hole transport layer 3. An electron injection layer may be provided between the cathode 7 and the first electron transport layer 6. The first electron transport layer and the second electron transport layer may be made of the same material or different materials.
The second electron transport layer 5 and the light emitting layer 4 are laminated in multiple layers. The film thickness of the second electron transport layer 5 is thinner than the light emitting layer 4, the film thickness of the second electron transport layer is preferably 1 nm or more and 5 nm or less, and the film thickness of the light emitting layer is preferably 5 nm or more and 20 nm or less. The light emitting layer 4 is hole transporting.
In addition, the second electron transport layer 5 and the light emitting layer 4 can be alternately laminated by 2 to n (n is a positive integer) layer.

Here, carrier movement and the like of the present invention will be described with reference to FIGS. 5 and 6 show band diagrams of FIG. FIG. 6 shows a band diagram of the light emitting layer 4 and the second electron transporting layer 5 in a portion laminated in multiple layers. The reference numerals are the same as those in FIG. Reference numeral 50 denotes a vacuum level, and 77 denotes an absolute value of an energy difference from the vacuum level 50 of the LUMO level of the first electron transport layer 6. Reference numeral 78 denotes an absolute value of an energy difference from the vacuum level 50 of the HOMO level of the first electron transport layer 6.
Reference numeral 70 denotes an absolute value of an energy difference from the vacuum level 50 of the LUMO level of the second electron transport layer 5, and reference numeral 71 denotes energy from the vacuum level 50 of the HOMO level of the second electron transport layer 5. Indicates the absolute value of the difference. 72 represents the absolute value of the energy difference from the vacuum level 50 of the LUMO level of the light emitting layer 4, and 73 represents the absolute value of the energy difference from the vacuum level 50 of the HOMO level of the light emitting layer 4.

  In the present invention, as described above, the absolute value of the energy difference 72 from the vacuum level of the LUMO level of the light emitting layer 4 is the absolute value of the energy difference 70 from the vacuum level of the LUMO level of the second electron transport layer 5. (The LUMO level of the light emitting layer is higher than the LUMO level of the second electron transport layer), and the absolute value of the energy difference 73 from the vacuum level of the HOMO level of the light emitting layer 4 is the second electron. The absolute value of the energy difference 71 from the vacuum level of the HOMO level of the transport layer 5 is smaller (the HOMO level of the light emitting layer is higher than the HOMO level of the second electron transport layer).

When a positive potential is applied to the anode 2 and a negative potential is applied to the cathode 7, holes (h ⁺ ) are injected from the anode 2 into the hole transport layer 3, while electrons (e ⁻ ) are transported from the cathode 7. Implanted into layer 6.
The electrons are transported from the first electron transport layer 6 to the light emitting layer 4 and recombined with the holes transported from the anode in the light emitting layer 4 to emit light. Since the light emitting layer 4 has a hole transport property, the probability that electrons recombine with holes is high. In the drawing, hν is indicated when light is emitted.

  Electrons that have not recombined with holes in the light-emitting layer 4 move toward the anode due to a potential difference. Next, it is injected into the second electron transport layer 5 and moves in the second electron transport layer 5. However, because of the barrier from the second electron transport layer to the light emitting layer 4 (energy difference 75: energy difference between the LUMO level of the light emitting layer 4 and the LUMO level of the second electron transport layer 5), the electrons emit light. The probability of being injected into layer 4 is reduced and trapped. Even if it is injected into the light emitting layer 4 over the barrier due to accumulation of electrons or the like, it recombines with holes in the light emitting layer 4 to emit light. Moreover, even if it is injected into the second electron transport layer 5 without being recombined in the light emitting layer 4, the barrier to the light emitting layer 4 is high as described above, and the probability of being confined is high. Therefore, the penetration into the hole transport layer 3 can be reduced and the luminous efficiency can be increased. In the case where the hole transport layer 3 is luminescent, when electrons are injected into the hole transport layer 3, they recombine with holes and emit light. When the emission wavelengths of the hole transport layer 3 and the light emitting layer 4 are different, color shift occurs.

  On the other hand, holes that have not recombined with electrons in the light emitting layer 4 move toward the cathode due to a potential difference. Here, since the second electron transport layer 5 is as thin as 1 nm or more and 5 nm or less, a barrier (energy difference 79: energy difference between the HOMO level of the light emitting layer 4 and the HOMO level of the second electron transport layer 5). Despite being present, it penetrates and is injected into the next light emitting layer 4. The light emitting layer 4 recombines with electrons to emit light. Further, even if it is not recombined in the light emitting layer 4, it is injected from the second electron transport layer 5 to the next light emitting layer 4.

  When the first electron transport layer 6 and the second electron transport layer 5 are different materials, the LUMO level of the first electron transport layer 6 and the LUMO level of the light emitting layer 4 are used in order to enhance the electron confinement effect. The absolute value of the energy difference 74 may be smaller than the absolute value of the energy difference 75. Thereby, the probability that the electrons injected from the cathode 7 cannot exceed the energy difference 75 can be increased.

Furthermore, if the energy difference 76 between the work function of the cathode 7 and the LUMO level of the first electron transport layer 6 and the potential applied to the anode and the cathode are controlled, the probability that electrons cannot exceed the energy difference 75 is further increased. Can be increased.
If the energy difference 76 is made smaller than the energy difference 75 and a voltage sufficient to exceed the energy difference 76 is applied, the electrons can exceed the energy difference 76, but the probability of exceeding the energy difference 75 decreases. Therefore, it is preferable to use the anode 2, the first electron transport layer, the light emitting layer 4, and the second electron transport layer having the above relationship, and further control the voltage applied to the anode and the cathode.

Hereinafter, materials and the like that can be used for each layer will be described.
As the substrate 1 and the anode 2, those described in Embodiment 1 can be used.

As a material for forming the cathode 7, a material having a work function of 2.8 to 3.0 eV, such as Ca, MgAg, Al, or Mg can be used.
For the first electron transport layer 6, Alq ₃ , BAlq ₃ , BCP, CBP, or the like can be used. Considering the energy difference from the second electron transport layer, the LUMO level is preferably -2.7 eV to -2.4 eV.
The second electron transport layer 5 may be made of the same material as the first electron transport layer 6. However, in order to enhance the electron confinement effect, the energy difference between the LUMO level of the first electron transport layer 6 and the LUMO level of the light emitting layer 4 is determined by the difference between the LUMO level of the second electron transport layer 5 and the light emitting layer 4. The energy difference from the LUMO level may be smaller. A LUMO level lower than −2.7 eV is preferable, and Alq ₃ , BAlq ₃ , diphenylquinoxaline, and the like can be used.

  Next, regarding the light emitting layer 4, the absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer 4 is the absolute value of the energy difference from the vacuum level of the HOMO level of the second electron transport layer 5. It is necessary to make it smaller than the value. Further, the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer 4 needs to be smaller than the absolute value of the energy difference from the vacuum level of the LUMO level of the second electron transport layer 5. is there. As a result, electrons can be confined as described above, and luminous efficiency can be increased. Further, penetration of electrons into the hole transport layer 3 can be prevented.

  On the other hand, the film thickness of the second electron transport layer 5 is thinner than that of the light emitting layer 4, the film thickness of the second electron transport layer is 1 nm or more and 5 nm or less, and the film thickness of the light emitting layer is 5 nm or more and 20 nm or less. Even if it has the above-mentioned energy relationship, holes penetrate the second electron transport layer 5 and are injected into the light emitting layer 4.

  For the light emitting layer 4, NPB, TCTA, TPD, or the like can be used. A LUMO level higher than −2.5 eV is preferable.

  As shown in Embodiment Mode 1, the light-emitting layer 4 is a host-guest type in which a light-emitting material is dispersed in a layer made of a material (host material) having an energy gap larger than that of a light-emitting substance (dopant material) serving as a light emission center. It is good also as a layer of.

  For the hole transport layer 3, for example, a compound of an aromatic amine (ie, having a benzene ring-nitrogen bond) such as TDATA, MTDATA, DNTPD, and αNPD can be used.

For example, those having the above energy difference relationship include Mg for the cathode 7, CBP for the first electron transport layer 6, TPD for the light emitting layer 4, and Alq _{3 for} the second electron transport layer 5. Of course, it is not limited to this combination. Further, FIG. 22 shows a band diagram when αNPD is used as the hole transport layer 3 and ITO is used as the anode.

  In FIG. 22, the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer 4 is smaller than the absolute value of the energy difference from the vacuum level of the LUMO level of the second electron transporting layer. The absolute value of the energy difference from the vacuum level of the HOMO level of the layer is smaller than the absolute value of the energy difference from the vacuum level of the HOMO level of the second electron transport layer.

  The energy difference 74 between the LUMO level of the first electron transporting layer and the LUMO level of the light emitting layer is smaller than the energy difference 75 between the LUMO level of the second electron transporting layer and the LUMO level of the light emitting layer. .

  The energy difference 76 between the work function of the cathode and the LUMO level of the first electron transport layer is smaller than the energy difference between the LUMO level of the second electron transport layer and the LUMO level of the light emitting layer. Therefore, electrons can be confined and luminous efficiency can be increased.

  Further, as shown in FIG. 2, a buffer layer 8 may be provided between the anode 2 and the first hole transport layer. The buffer layer 8 may be a mixture of an organic compound and a metal compound. The thickness of the buffer layer may be 60 nm or more. In the case of the present invention, even if the thickness of the buffer layer is increased, the drive voltage is not increased.

  The first electron transport layer 6, the light emitting layer 4, the second electron transport layer 5, and the hole transport layer 6 can be formed by an evaporation method. The buffer layer 8 can be formed by co-evaporation of an organic compound and a metal compound. The anode and cathode can be formed by a known sputtering method or vapor deposition method. The hole injection layer and the electron injection layer can also be formed by a known vapor deposition method or the like. Moreover, the light emitting layer 4 and the 2nd electron carrying layer 5 are producible by the method mentioned later.

  The method for measuring the HOMO level and the LUMO level is as described in the first embodiment.

(Embodiment 3)
A vapor deposition apparatus used in the practice of the present invention and a method for manufacturing the multi-layered structure portion described in the first and second embodiments using the vapor deposition apparatus will be described with reference to FIGS.

  In the vapor deposition apparatus used for carrying out the present invention, a transfer chamber 1002 is provided in addition to a treatment chamber 1001 for performing a vapor deposition process on a workpiece. The object to be processed is transferred to the processing chamber 1001 through the transfer chamber 1002. The transfer chamber 1002 is provided with an arm 1003 for transferring an object to be processed (FIG. 7).

  In the processing chamber 1001, as shown in FIG. 8, a holding unit 100 for holding a substrate 101 which is a deposition target, an evaporation source 102 holding a light emitting material, and an evaporation holding a carrier transport material. A source 103 is provided. The evaporation sources 102 and 103 are partitioned by a partition 104. A shutter 105b is provided on the evaporation source 102 holding the light emitting material, and a shutter 105a is provided on the evaporation source 103 holding the carrier transport material.

  When a dopant material is added to the light emitting material, an evaporation source of the dopant material is provided together with the evaporation source 102 of the host material, and the dopant material is co-deposited together with the host material.

  In the state where the shutter 105b is opened and the shutter 105a is closed as shown in FIG. 8A, the light emitting material is deposited on the substrate 101, but the carrier transporting material is not deposited. Next, when the shutter 105b is closed and the shutter 105a is opened as shown in FIG. 8B, the carrier transport material is deposited on the substrate 101, but the light emitting material is not deposited. By this method, the carrier transport material and the light emitting material can be alternately deposited, and a multi-layered structure can be manufactured.

  In the present invention, since the thickness of the second carrier transport layer 5 is thinner than the thickness of the light emitting layer 4, the time for the shutter 105b to be opened may be lengthened and the time for the shutter 105a to be opened may be shortened. Thereby, the deposition amount of the carrier transport material is reduced, and the film thickness can be reduced. In this manner, the configuration of the above embodiment can be manufactured by controlling the time during which the shutters 105a and 105b are opened.

  At this time, the film thickness can also be controlled by changing the deposition rate. When the deposition rate is lowered, the deposition amount per unit time can be reduced and the film thickness can be reduced. Conversely, when the deposition rate is increased, the deposition amount can be increased and the film thickness can be increased. When the deposition rate of the carrier transport material is lowered when the shutter 105a is open and the deposition rate of the light emitting material is increased when the shutter 105b is open, the thickness of the carrier transport layer can be made thinner than the thickness of the light emitting layer.

  Further, the adsorption speed may be changed by changing the temperature of the substrate.

  The substrate 101 may be rotated as shown by an arrow. By rotating, the film thicknesses of the carrier transport layer and the light emitting layer in the substrate plane can be made uniform.

  The configuration in the processing chamber 1001 is not limited to that shown in FIG. 8, and for example, the configuration shown in FIGS. 9 to 13 may be used.

  9 and 10, a holding unit for holding a substrate that is an evaporation target, an evaporation source 102 that holds a light emitting material, and an evaporation source 103 that holds a carrier transport material are provided. The evaporation sources 102 and 103 are partitioned by a partition 104. A shutter 105a is provided on the evaporation source 103 on which the carrier transport material is held.

  In the state where the shutter 105a is closed as shown in FIG. 9, the light emitting material is deposited on the substrates 1015a to 1015d, but the carrier transporting material is not deposited. Conversely, when the shutter 105a is opened as shown in FIG. 10, a carrier transport material is deposited on the substrates 1015a to 1015d.

  If the time during which the shutter 105a is opened is shortened, the deposition amount of the carrier transport material is decreased. Conversely, if the time during which the shutter 105a is opened is lengthened, the deposition amount of the carrier transport material can be increased. In this manner, the film thickness of the carrier transport layer and the light emitting layer can be controlled by controlling the deposition amount of the carrier transport material by opening and closing the shutter 105a. The steps so far are the same as in FIG.

  Here, the holding unit for holding the substrate includes a first rotating plate 1012 that rotates about a shaft 1013 and a plurality of second rotating plates 1014 a to 1014 d provided on the first rotating plate 1012. It is configured. The second rotating plates 1014a to 1014d rotate independently of each other around the shafts provided for the second rotating plates 1014a to 1014d, separately from the shaft 1013. The substrates 1015a to 1015d are held on the second rotating plates 1014a to 1014d, respectively.

  The second rotating plate 1014a holds the substrate 1015a, the second rotating plate 1014b holds the substrate 1015b, the second rotating plate 1014c holds the substrate 1015c, and the second rotating plate 1014d holds the substrate 1015b. A substrate 1015d is held.

  The first rotating plate 1012 and the second rotating plates 1014a to 1014d holding the substrate are rotating. The substrate rotates by the rotation of the second rotating body. This is the same as the rotation of the substrate in FIG. 8. By rotating, the film thickness of the light emitting layer and the carrier transport layer in the substrate surface can be made uniform.

  On the other hand, the substrate is revolved by the rotation of the first rotating plate 1012. As shown in FIG. 10 where the shutter 105a is in the open state, when the distance between the substrate 1015a and the light emitting material evaporation source 102 is shorter than the distance between the substrate 1015a and the carrier transport material evaporation source 103, the substrate A light emitting layer is formed on 1015a by depositing more light emitting material than carrier transporting material. On the other hand, when the distance between the substrate 1015c and the carrier transport material evaporation source 103 is shorter than the distance between the substrate 1015c and the light emitting material evaporation source 102 as in the substrate 1015c, the substrate 1015c has a larger distance than the light emitting material. More carrier transport material is deposited to form a carrier transport layer.

  Next, the rotation of the first rotating plate 1012 changes the position of the second rotating plate 1014a in the processing chamber 1001, and the substrate 1015a is held at the position of the second rotating plate 1014c in FIG. When the distance from the carrier transport material evaporation source 103 is shorter than the distance from the substrate 1015a to the light emitting material evaporation source 102, more carrier transport layer material is deposited on the substrate 1015a than the light emitting material to form a carrier transport layer. Is done. Thereby, a light emitting layer and a carrier transport layer can be laminated | stacked alternately, and a multiple laminated structure can be produced.

  In the present invention, since the thickness of the carrier transport layer is smaller than the thickness of the light emitting material, the shutter 105a is used to control the thickness of the carrier transport layer or to change the deposition rate of the light emitting material and the carrier transport material. May be used to control the film thickness. Further, the film thickness may be changed by changing the adsorption speed by changing the temperature of the substrate.

  As described above, the light emitting layers and the carrier transport layers can be alternately stacked by changing the positions of the substrates 1015a to 1015d with respect to the evaporation sources 102 and 103, thereby realizing a multi-layered structure.

  In addition, there is no limitation in particular about the shape of the 1st rotary plate 1012 and the 2nd rotary plate 1014a-1014d, Polygons, such as a quadrangle | tetragon other than the circle | round | yen represented to FIGS. In addition, the second rotating plates 1014a to 1014d are not necessarily provided, but by providing the second rotating plates 1014a to 1014d, in-plane variations such as the thickness of a layer formed on the object to be processed are provided. Can be reduced.

  9 and 10 has an advantage that it becomes a batch type and a plurality of substrates can be processed at a time.

  In FIG. 11, masks 108a and 108b that rotate about axes 109a and 109b are provided on the evaporation source of the carrier transport material and the light emitting material, and holes 106 and 110 are provided in the masks 108a and 108b.

  When the hole 106 provided in the mask 108b is above the evaporation source 102, a luminescent material is deposited. At this time, when the hole 110 provided in the mask 108a is not on the evaporation source 103, the carrier transporting material is not deposited (FIG. 11A).

  Next, when the mask 108 is rotated and the hole 106 provided in the mask 108b is not on the evaporation source 102, the light emitting material is not deposited. At this time, when the hole 110 provided in the mask 108a is above the evaporation source 103, a carrier transport material is deposited (FIG. 11B). Therefore, by using such a mask and controlling the rotation speed, a light-emitting layer and a carrier transport layer can be alternately stacked to produce a multi-layered structure.

  Further, the deposition amount may be controlled by changing the deposition rate of the light emitting material and the carrier transporting material.

  Further, the adsorption speed may be changed by changing the temperature of the substrate.

  The shape of the hole in the mask can be changed to various shapes as required. A slit 111 may be provided (FIG. 12). The hole of the mask 108a may be shaped like 112 (FIG. 13). Further, the hole of the mask 108b may be made circular like 110, or may be made slit like 111.

  In addition, in the configuration of FIGS. 11 to 13, as shown in FIGS. 9 and 10, a first rotating plate 1012 that rotates about a shaft 1013 and a plurality of second rotations provided on the first rotating plate 1012. Plates 1014a to 1014d, the substrates are held on the second rotating plates 1014a to 1014d, and the first rotating plate and the second rotating plate are rotated to alternately stack the light emitting layers and the carrier transport layers. Thus, a multi-layered structure may be formed. Note that this embodiment can be combined with any of the above structures.

(Embodiment 4)
A structural example and a manufacturing method of the light-emitting device of the present invention will be described with reference to FIGS. Here, the case where the carrier transport layer is a hole transport layer will be described. In the figure, 1 is a substrate, 2 is an anode, 3 is a first hole transport layer, 4 is a light emitting layer, 5 is a second hole transport layer, 6 is an electron transport layer, and 7 is a cathode.

  An anode 2 made of ITO is formed on the glass substrate 1 by sputtering.

  ΑNPD is deposited on the anode 2 as a first hole transport layer 3 by vapor deposition.

On the first hole transport layer 3, the light emitting layer 4 and the second hole transport layer 5 are formed in a multi-layer structure. Alq ₃ is used for the light emitting layer 4 and MTDATA is used for the second hole transport layer 5.

  The apparatus shown in FIG. 8 is used for forming the light emitting layer 4 and the second hole transport layer 5. The light emitting material is put into the evaporation source 102 and the second hole transport material is put into the evaporation source 103, and heated in a vacuum to be evaporated. The vapor deposition rate of the light emitting material and the second hole transport material is 0.01 to 0.4 nm / s.

  The ratio of the time when the shutter 105a is opened to the time when the shutter 105b is opened is 10: 1 to 4: 1. When the shutter 105b is open, the shutter 105a is closed. Conversely, when the shutter 105a is open, the shutter 105b is closed.

  Thereby, the light emitting layer 4 is 5 nm or more and 20 nm or less, the second hole transport layer 5 is 1 nm or more and 5 nm or less, and the light emitting layer 4 and the second hole transport layer 5 are formed over 2 to 10 layers. (For example, in the case of two layers, the substrate 1, the anode 2, the first hole transport layer 3, the light emitting layer 4, the second hole transport layer 5, the light emitting layer 4, the second hole transport layer 5, The light emitting layer 4, the electron transport layer 6, and the cathode 7. The light emitting layer 4 and the second hole transport layer 5 are laminated twice). The last layer in the multi-layered structure is the light emitting layer 4.

Next, Almq ₃ is deposited on the light emitting layer 4 as an electron transport layer 6 by vapor deposition. Thereafter, the MgAg cathode 7 is formed by vapor deposition.

  An energy band diagram of this embodiment is shown in FIG. In FIG. 21, the absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer 4 is larger than the absolute value of the energy difference from the vacuum level of the LUMO level of the second hole transport layer (light emission). The LUMO level of the layer is lower than the LUMO level of the hole transport layer), and the absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is the HOMO level of the second hole transport layer. It is larger than the absolute value of the energy difference from the vacuum level (the HOMO level of the light emitting layer is lower than the HOMO level of the hole transport layer).

  The energy difference 59 between the HOMO level of the first hole transport layer and the HOMO level of the light emitting layer is based on the energy difference 58 between the HOMO level of the second hole transport layer and the HOMO level of the light emitting layer. Is also small.

  The energy difference 57 between the work function of the anode and the HOMO level of the first hole transport layer is smaller than the energy difference 58 between the HOMO level of the second hole transport layer and the HOMO level of the light emitting layer. . Accordingly, holes can be confined and luminous efficiency can be increased.

A buffer layer may be provided between the anode 2 and the first hole transport layer 3. A hole injection layer or an electron injection layer may be provided. Alternatively, a light emitting layer 4 may be formed by adding a dopant material to a host material. For example it is possible to add a dopant material, such as and rubrene shown in the host material Alq ₃ in the above embodiment.

  Although the method shown in FIG. 8 has been described here, the present invention is not limited to this. Of course, it can be produced by the method shown in FIGS. The manufacturing method in each case is as described in the above embodiment.

  From the above, by applying this configuration, it is possible to form a multi-layered structure in which light emitting layers made of organic compounds and carrier transport layers made of organic compounds are alternately stacked. Since it is not a laminated structure with a layer made of an inorganic compound, no stress is generated and a light emitting device with little characteristic deterioration can be obtained, and a light emitting device with high luminous efficiency can be obtained.

  Further, in this light emitting device, the light emitting layer and the carrier transport layer have different polarities, the thickness of the carrier transport layer is smaller than that of the light emitting layer, and the light emitting layer and the carrier transport layer having the LUMO level and the HOMO level are provided. Have. As a result, carriers having the same polarity as the carrier transport layer are easily confined, and carriers having different polarities move by the tunnel effect. That is, one carrier can be confined, and the luminous efficiency can be increased.

  Further, the flatness can be improved by providing a buffer layer made of an organic compound and a metal compound between the electrode and the carrier transport layer. Furthermore, a multilayer structure can be easily manufactured by carrying out the manufacturing method of this embodiment.

(Embodiment 5)
In this embodiment mode, a light-emitting device of the present invention will be described with reference to FIGS. In this embodiment, an example in which an active matrix light-emitting device is formed is shown. However, it is needless to say that the present invention is not limited to the active matrix type and can be used for a passive matrix type light emitting device.

  First, after the first base insulating layer 251a and the second base insulating layer 251b are formed over the substrate 250, a semiconductor layer is further formed over the second base insulating layer 251b. (Fig. 14 (A))

  As a material of the substrate 250, glass, quartz, plastic (polyimide, acrylic, polyethylene terephthalate, polycarbonate, polyacrylate, polyethersulfone, or the like) can be used. These substrates may be used after being polished by CMP or the like, if necessary. In this embodiment, a glass substrate is used.

  The first base insulating layer 251a and the second base insulating layer 251b prevent an element such as an alkali metal or an alkaline earth metal in the substrate 250 that adversely affects the characteristics of the semiconductor film from diffusing into the semiconductor layer. Provided for this purpose. As a material, silicon oxide, silicon nitride, silicon oxide containing nitrogen, silicon nitride containing oxygen, or the like can be used. In this embodiment, the first base insulating layer 251a is formed using silicon nitride, and the second base insulating layer 251b is formed using silicon oxide. In this embodiment mode, the base insulating layer is formed using two layers of the first base insulating layer 251a and the second base insulating layer 251b. It doesn't matter. In addition, it is not necessary to provide a base insulating layer as long as the diffusion of impurities from the substrate does not matter.

  In this embodiment mode, a semiconductor layer formed subsequently is obtained by laser crystallization of an amorphous silicon film. An amorphous silicon film is formed to a thickness of 25 to 100 nm (preferably 30 to 60 nm) over the second base insulating layer 251b. As a manufacturing method, a known method such as a sputtering method, a low pressure CVD method or a plasma CVD method can be used. Thereafter, heat treatment is performed at 400 to 500 ° C. (for example, 500 ° C. for 1 hour), and hydrogen is extracted.

  Subsequently, the amorphous silicon film is crystallized using a laser irradiation apparatus to form a crystalline silicon film. In the laser crystallization of this embodiment, an excimer laser is used, and a laser beam oscillated is processed into a linear beam spot using an optical system and irradiated to an amorphous silicon film to form a crystalline silicon film. Used as a semiconductor layer.

Other crystallization methods for the amorphous silicon film include a method for crystallization only by heat treatment and a method for heat treatment using a catalyst element that promotes crystallization. Examples of elements that promote crystallization include nickel, iron, palladium, tin, lead, cobalt, platinum, copper, and gold. Compared to the case where crystallization is performed only by heat treatment by using such an element, Since crystallization is performed at a low temperature for a short time, there is little damage to the glass substrate. When crystallization is performed only by heat treatment, the substrate 250 may be a quartz substrate that is resistant to heat.
Moreover, you may combine crystallizing by laser processing and crystallizing by irradiating a laser beam. That is, crystallization may be performed by irradiating a laser beam after crystallization by heat treatment using a catalytic element that promotes crystallization.

  Subsequently, in order to control the threshold value in the semiconductor layer as required, a small amount of impurity addition, so-called channel doping is performed. In order to obtain a required threshold value, N-type or P-type impurities (phosphorus, boron, etc.) are added by an ion doping method or the like.

  After that, as illustrated in FIG. 14A, the semiconductor layer is patterned into a predetermined shape, so that an island-shaped semiconductor layer 252 is obtained. Patterning is performed by forming a photoresist on the semiconductor layer, exposing a predetermined mask shape, baking, forming a resist mask on the semiconductor layer, and etching using the mask.

  Subsequently, a gate insulating layer 253 is formed so as to cover the semiconductor layer 252. The gate insulating layer 253 is formed of an insulating layer containing silicon with a thickness of 40 to 150 nm by a plasma CVD method or a sputtering method. In this embodiment mode, silicon oxide is used.

  Next, the gate electrode 254 is formed over the gate insulating layer 253. The gate electrode 254 may be formed using an element selected from tantalum, tungsten, titanium, molybdenum, aluminum, copper, chromium, and niobium, or an alloy material or a compound material containing these elements as a main component. Alternatively, a semiconductor film typified by a polycrystalline silicon film doped with an impurity element such as phosphorus may be used. Further, an AgPdCu alloy may be used.

  In this embodiment mode, the gate electrode 254 is formed as a single layer; however, it may have a stacked structure of two or more layers such as tungsten in the lower layer and molybdenum in the upper layer. Even in the case where the gate electrode is formed as a stacked structure, the materials described in the preceding stage may be used. Moreover, the combination may be selected as appropriate. The gate electrode 254 is processed by etching using a mask using a photoresist.

  Subsequently, a high concentration impurity is added to the semiconductor layer 252 using the gate electrode 254 as a mask. Thus, the thin film transistor 270 including the semiconductor layer 252, the gate insulating layer 253, and the gate electrode 254 is formed. Here, the LDD region 257 may be provided in addition to the source region 255 and the drain region 256 by using low-speed ion doping or high-speed ion doping.

  Note that there is no particular limitation on the manufacturing process of the thin film transistor, and it may be changed as appropriate so that a transistor with a desired structure can be manufactured.

  In this embodiment mode, a top-gate thin film transistor using a crystalline silicon film crystallized by laser crystallization is used; however, a bottom-gate thin film transistor using an amorphous semiconductor film is used for a pixel portion. It is also possible. As the amorphous semiconductor, not only silicon but also silicon germanium can be used. When silicon germanium is used, the concentration of germanium is preferably about 0.01 to 4.5 atomic%.

  Alternatively, a microcrystalline semiconductor film (semi-amorphous semiconductor) in which a crystal grain of 0.5 nm to 20 nm can be observed in an amorphous semiconductor may be used. Microcrystals capable of observing crystal grains of 0.5 nm to 20 nm are also called so-called microcrystals (μc).

Semi-amorphous silicon (also referred to as SAS) that is a semi-amorphous semiconductor can be obtained by glow discharge decomposition of a silane-based gas. A typical silane-based gas is SiH ₄ , and Si ₂ H ₆ , SiH ₂ Cl ₂ , SiHCl ₃ , SiCl ₄ , SiF _{4, and the} like can be used. The formation of the SAS can be facilitated by diluting the silane-based gas with one or plural kinds of rare gas elements selected from hydrogen, hydrogen and helium, argon, krypton, and neon. It is preferable to dilute the silane-based gas in the range of 10 to 1000 times the dilution rate. The reaction generation of the film by glow discharge decomposition may be performed at a pressure in the range of 0.1 Pa to 133 Pa. The power for forming the glow discharge may be high frequency power of 1 MHz to 120 MHz, preferably 13 MHz to 60 MHz. The substrate heating temperature is preferably 300 ° C. or less, and a substrate heating temperature of 100 to 250 ° C. is suitable.

The SAS thus formed has a Raman spectrum shifted to a lower wavenumber than 520 cm ⁻¹ , and diffraction peaks of (111) and (220), which are considered to be derived from the Si crystal lattice in X-ray diffraction, are observed. Is done. At least 1 atom% or more of hydrogen or halogen is contained for termination of dangling bonds. As an impurity element in the film, an impurity of atmospheric components such as oxygen, nitrogen, and carbon is desirably 1 × 10 ²⁰ cm ⁻³ or less, and in particular, the oxygen concentration is 5 × 10 ¹⁹ cm ⁻³ or less, preferably 1 × 10 ¹⁹ cm ^-3 or less. When SAS is used, the mobility when TFT is used is μ = 1 to 10 cm ² / Vsec.

  Further, the SAS may be further crystallized by irradiating with laser light.

  Subsequently, an insulating film (hydrogenated film) 259 is formed of silicon nitride so as to cover the gate electrode 254 and the gate insulating layer 253. When the insulating film (hydrogenated film) 259 is formed, heating is performed at 400 to 500 ° C. (for example, at 480 ° C. for about 1 hour) to activate the impurity element and hydrogenate the semiconductor layer 252.

  Subsequently, a first interlayer insulating layer 260 covering the insulating film (hydrogenated film) 259 is formed. As a material for forming the first interlayer insulating layer 260, silicon oxide, acrylic, polyimide, siloxane, a low dielectric constant material, or the like is preferably used. In this embodiment mode, the silicon oxide film is formed as the first interlayer insulating layer. (Fig. 14B)

  Next, a contact hole reaching the semiconductor layer 252 is opened. The contact hole can be formed by etching using a resist mask until the semiconductor layer 252 is exposed, and can be formed by either wet etching or dry etching. Note that etching may be performed once depending on conditions, or etching may be performed in a plurality of times. In addition, when etching is performed a plurality of times, both wet etching and dry etching may be used. (Figure 14 (C))

  Then, a conductive layer covering the contact hole and the first interlayer insulating layer 260 is formed. The conductive layer is processed into a desired shape, so that a connection portion 261a, a wiring 261b, and the like are formed. This wiring may be a single layer of aluminum, copper, an alloy of aluminum, carbon, and nickel, an alloy of aluminum, carbon, and molybdenum, or a laminated structure of molybdenum, aluminum, molybdenum, titanium, and aluminum from the substrate side. A structure such as titanium, titanium, titanium nitride, aluminum, or titanium may be used. (Fig. 14D)

  After that, a second interlayer insulating layer 263 is formed so as to cover the connection portion 261a, the wiring 261b, and the first interlayer insulating layer 260. As a material for the second interlayer insulating layer 263, a film of acrylic, polyimide, siloxane, or the like having self-flatness can be preferably used. In this embodiment mode, siloxane is used as the second interlayer insulating layer 263. (Fig. 14 (E))

  Subsequently, an insulating layer may be formed using silicon nitride or the like over the second interlayer insulating layer 263 (not shown). This is formed to prevent the second interlayer insulating layer 263 from being etched more than necessary in the subsequent etching of the pixel electrode. Therefore, when the ratio of the etching rate between the pixel electrode and the second interlayer insulating layer is large, it may not be provided. Subsequently, a contact hole that penetrates the second interlayer insulating layer 263 and reaches the connection portion 261a is formed.

  A light-transmitting conductive layer is formed so as to cover the contact hole and the second interlayer insulating layer 263 (or the insulating layer), and then the light-transmitting conductive layer is processed to form the first light-emitting element. The electrode 264 is formed. Here, the first electrode 264 is in electrical contact with the connection portion 261a (FIG. 15A).

  The first electrode 264 functions as an anode. Here, those described in the above embodiment can be used.

  Next, an insulating layer made of an organic material or an inorganic material is formed so as to cover the second interlayer insulating layer 263 (or the insulating layer) and the first electrode 264. Subsequently, the insulating layer is processed so that part of the first electrode 264 is exposed, so that a partition wall 265 is formed. As a material for the partition wall 265, an organic material having photosensitivity (acrylic, polyimide, or the like) is preferably used, but an organic material or an inorganic material having no photosensitivity may be used. In addition, a black pigment or dye such as titanium black or carbon nitride may be dispersed in the material of the partition wall 265 using a dispersing material or the like, and the partition wall 265 may be blackened to be used like a black matrix. It is desirable that the end surface of the partition wall 265 facing the first electrode has a curvature, and has a tapered shape in which the curvature continuously changes (FIG. 15B).

  Next, a buffer layer including a mixed layer of an organic compound and a metal compound is formed so as to cover the first electrode 264 exposed from the partition wall 265. What was shown to the said embodiment can be used. Subsequently, a first hole transport layer is formed. Thereafter, the light emitting layer and the second hole transport layer are alternately laminated n times, and finally the light emitting layer is formed. Then, an electron transport layer is laminated on the light emitting layer.

  Subsequently, a second electrode 267 functioning as a cathode is formed. Thus, a light-emitting device 293 having a multi-layer structure using an organic light-emitting layer and a carrier transport layer made of an organic compound between the first electrode 264 and the second electrode 267 can be manufactured. Light can be obtained by applying a higher voltage to the second electrode than the second electrode.

Thereafter, a silicon oxide film containing nitrogen is formed as a passivation film by a plasma CVD method. In the case of using a silicon oxide film containing nitrogen, a silicon oxynitride film manufactured from SiH ₄ , N ₂ O, NH ₃ by a plasma CVD method, or a silicon oxynitride film manufactured from SiH ₄ , N ₂ O, Alternatively, a silicon oxynitride film formed from a gas obtained by diluting SiH ₄ and N ₂ O with Ar may be formed.

Further, a silicon oxynitride silicon film formed from SiH ₄ , N ₂ O, and H ₂ may be applied as the passivation film. Of course, the passivation film is not limited to a single layer structure, and another insulating layer containing silicon may be used as a single layer structure or a laminated structure. Further, a multilayer film of carbon nitride film and silicon nitride film, a multilayer film of styrene polymer, a silicon nitride film, or a diamond-like carbon film may be formed instead of the silicon oxide film containing nitrogen.

  Subsequently, the display portion is sealed in order to protect the light emitting element from a substance that promotes deterioration such as water. In the case where the counter substrate is used for sealing, bonding is performed with an insulating sealing material so that the external connection portion is exposed. A space between the counter substrate and the element substrate may be filled with an inert gas such as dry nitrogen, or a sealant may be formed on the entire surface of the pixel portion so that the counter substrate is bonded. It is preferable to use an ultraviolet curable resin or the like for the sealing material. The sealing material may contain a desiccant or particles for keeping the gap between the substrates constant. Then, a flexible wiring board is affixed on an external connection part.

  An example of the structure of the light-emitting device manufactured as described above will be described with reference to FIGS. In addition, even if the shapes are different, parts showing similar functions are denoted by the same reference numerals, and explanations thereof are omitted. In this embodiment mode, the thin film transistor 270 having an LDD structure is connected to the light-emitting device 293 through the connection portion 261a.

  FIG. 16A illustrates a structure in which the first electrode 264 is formed using a light-transmitting conductive film and light emitted from the light-emitting stack 266 is extracted to the substrate 250 side. Note that reference numeral 294 denotes a counter substrate, which is fixed to the substrate 250 using a sealant or the like after the light emitting device 293 is formed. By filling and sealing a light-transmitting resin 288 or the like between the counter substrate 294 and the element, the light-emitting device 293 can be prevented from being deteriorated by moisture. It is desirable that the resin 288 has a hygroscopic property. Further, when a highly light-transmitting desiccant 289 is dispersed in the resin 288, the influence of moisture can be further suppressed, which is a more desirable form.

  FIG. 16B illustrates a structure in which both the first electrode 264 and the second electrode 267 are formed using a light-transmitting conductive film, and light can be extracted to both the substrate 250 and the counter substrate 294. It has become. Further, in this structure, by providing the polarizing plate 290 outside the substrate 250 and the counter substrate 294, it is possible to prevent the screen from being seen through, and visibility is improved. A protective film 291 may be provided outside the polarizing plate 290.

  There is no particular limitation on the arrangement of the transistor, the light-emitting device, and the like in the pixel portion. In FIG. 17, the first electrode of the first transistor 2001 is connected to the source signal line 2004, and the second electrode is connected to the gate electrode of the second transistor 2002. The first electrode of the second transistor is connected to the current supply line 2005, and the second electrode is connected to the electrode 2006 of the light emitting element. Part of the gate signal line 2003 functions as a gate electrode of the first transistor 2001.

  Note that either an analog video signal or a digital video signal may be used for the light-emitting device of the present invention having a display function. When a digital video signal is used, the video signal is classified into one using a voltage and one using a current. When the light emitting device emits light, the video signal input to the pixel is either constant voltage or constant current, and the video signal is constant voltage, the voltage applied to the light emitting device is constant. And the current flowing through the light emitting device is constant. In addition, the video signal having a constant current includes a constant voltage applied to the light emitting device and a constant current flowing in the light emitting device. A constant voltage applied to the light emitting device is constant voltage driving, and a constant current applied to the light emitting device is constant current driving. In constant current driving, a constant current flows regardless of the resistance change of the light emitting device. In the light emitting device and the driving method thereof according to the present invention, either a voltage driving method or a current driving method may be used, and either constant voltage driving or constant current driving may be used.

  This embodiment mode can be used in combination with an appropriate structure of the above embodiment mode.

(Embodiment 6)
In this embodiment mode, the appearance of a panel which is a light-emitting device of the present invention will be described with reference to FIGS. 18 is a top view of a panel in which a transistor and a light-emitting device formed over a substrate are sealed with a sealant formed between a counter substrate 4006 and FIG. 18B is a cross-sectional view of FIG. It corresponds to. Further, the structure of the light emitting device mounted on this panel has a structure as shown in the fifth embodiment.

  A sealant 4005 is provided so as to surround the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004 which are provided over the substrate 4001. A counter substrate 4006 is provided over the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004. Therefore, the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004 are sealed together with the filler 4007 by the substrate 4001, the sealant 4005, and the counter substrate 4006.

  Further, the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004 provided over the substrate 4001 include a plurality of thin film transistors. In FIG. 18B, the thin film transistor 4008 included in the signal line driver circuit 4003 is provided. And a thin film transistor 4010 included in the pixel portion 4002.

In addition, the light-emitting device 4011 is electrically connected to the thin film transistor 4010.
The light-emitting device 4011 includes an anode, a hole transport layer, a light-emitting layer, a second electron transport layer, a light-emitting layer, a second electron transport layer, a light-emitting layer, a second electron transport layer,. The electron transport layer is composed of a cathode.

  The lead wiring 4014 corresponds to a wiring for supplying a signal or a power supply voltage to the pixel portion 4002, the signal line driver circuit 4003, and the scan line driver circuit 4004. The lead wiring 4014 is connected to the connection terminal 4016 through the lead wiring 4015. The connection terminal 4016 is electrically connected to a terminal included in a flexible printed circuit (FPC) 4018 through an anisotropic conductive film 4019.

  Note that as the filler 4007, in addition to an inert gas such as nitrogen or argon, an ultraviolet curable resin or a thermosetting resin can be used, and polyvinyl chloride, acrylic, polyimide, epoxy resin, silicon resin, polyvinyl butyral, Alternatively, ethylene vinylene acetate can be used.

  Note that the present invention includes in its category a panel in which a pixel portion having a light-emitting device is formed and a module in which an IC is mounted on the panel.

  This embodiment can be used in combination with an appropriate structure of the above embodiment.

(Embodiment 7)
As an electronic apparatus having a light emitting device of the present invention in which a module as shown in the above embodiment is mounted, a video camera, a camera such as a digital camera, a goggle type display (head mounted display), a navigation system, and sound reproduction Device (car audio component etc.), computer, game machine, portable information terminal (mobile computer, mobile phone, portable game machine or electronic book etc.), image playback device (specifically DigiAl Versatile Disc (equipment) with recording medium) DVD) and the like, and a device provided with a display capable of displaying the image. Specific examples of these electronic devices are shown in FIGS.

  FIG. 19A illustrates a television receiver, a personal computer monitor, and the like. A housing 3001, a display portion 3003, a speaker portion 3004, and the like are included. The display portion 3003 is provided with an active matrix display device. The display portion 3003 includes the light-emitting device and the TFT having the multilayer structure of the present invention for each pixel. By having the light-emitting device of the present invention, a television with less characteristic deterioration and high light emission efficiency can be obtained.

  FIG. 19B illustrates a cellular phone, which includes a main body 3101, a housing 3102, a display portion 3103, a voice input portion 3104, a voice output portion 3105, operation keys 3106, an antenna 3108, and the like. The display portion 3103 is provided with an active matrix display device. The display portion 3103 includes the light-emitting device and the TFT having the multilayer structure of the present invention for each pixel. By having the light-emitting device of the present invention, a cellular phone with little emission degradation and high luminous efficiency can be obtained.

  FIG. 19C illustrates a computer, which includes a main body 3201, a housing 3202, a display portion 3203, a keyboard 3204, an external connection port 3205, a pointing mouse 3206, and the like. The display portion 3203 is provided with an active matrix display device. The display portion 3203 includes the light-emitting device and the TFT having the multilayer structure of the present invention for each pixel. By having the light emitting device of the present invention, a computer with little characteristic deterioration and high light emission efficiency can be obtained.

  FIG. 19D illustrates a mobile computer, which includes a main body 3301, a display portion 3302, a switch 3303, operation keys 3304, an infrared port 3305, and the like. The display portion 3302 is provided with an active matrix display device. The display portion 3302 includes the light-emitting device and the TFT having a multilayer structure of the present invention for each pixel. By having the light-emitting device of the present invention, a mobile computer with little characteristic deterioration and high luminous efficiency can be obtained.

  FIG. 19E illustrates a portable game machine including a housing 3401, a display portion 3402, speaker portions 3403, operation keys 3404, a recording medium insertion portion 3405, and the like. The display portion 3402 is provided with an active matrix display device. The display portion 3402 includes the light-emitting device and the TFT having the multilayer structure of the present invention for each pixel. By having the light emitting device of the present invention, a portable game machine with little characteristic deterioration and high light emission efficiency can be obtained.

  FIG. 20A illustrates a flexible display, which includes a main body 3110, a pixel portion 3111, a driver IC 3112, a receiving device 3113, a film battery 3114, and the like. The receiving device can receive a signal from the infrared communication port 3107 of the mobile phone. The pixel portion 3111 is provided with an active matrix display device. The pixel portion 3111 includes the light emitting device and the TFT having a multi-layer structure of the present invention for each pixel. By having the light emitting device of the present invention, a flexible display with little deterioration in characteristics and high light emission efficiency can be obtained.

  FIG. 20B illustrates an ID card manufactured by applying the present invention, which includes a support body 5541, a display portion 5542, an integrated circuit chip 5543 incorporated in the support body 5541, and the like.

  The display portion 5542 is provided with an active matrix display device. The display portion 5542 is provided with an active matrix display device. The display portion 5542 includes the light-emitting device and the TFT having the multilayer structure of the present invention for each pixel. By having the light emitting device of the present invention, it is possible to obtain an ID card with little characteristic deterioration and high luminous efficiency.

  As described above, the applicable range of the present invention is so wide that it can be used for electronic devices in various fields.

4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. 10A and 10B illustrate a method for manufacturing a TFT. 4A and 4B illustrate a method for manufacturing a light-emitting device of the present invention. FIG. 6 illustrates a cross section of a light-emitting device of the present invention. FIG. 6 illustrates an appearance of a light-emitting device of the present invention. 4A and 4B each illustrate an upper surface of a pixel portion of a light-emitting device of the present invention. 4A and 4B each illustrate an electronic device using a light-emitting device of the present invention. 4A and 4B each illustrate an electronic device using a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention. 4A and 4B illustrate a light-emitting device of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Carrier transport layer 4 Light emitting layer 5 Carrier transport layer 6 Carrier transport layer 7 Cathode 8 Buffer layer 50 Vacuum level 51 Energy difference 52 Energy difference 53 Energy difference 54 Energy difference 55 Energy difference 56 Energy difference 57 Energy difference 58 Energy difference 59 energy difference 60 energy difference 70 energy difference 71 energy difference 72 energy difference 73 energy difference 74 energy difference 75 energy difference 76 energy difference 77 energy difference 78 energy difference 79 energy difference 100 holder 101 substrate 102 evaporation source 103 evaporation source 104 Partition 105a Shutter 105b Shutter 106 Hole 108a Mask 108b Mask 109a Shaft 109b Shaft 110 Hole 111 Slit 112 Hole 250 Substrate 251a Insulating layer 251b Insulating layer 52 Semiconductor layer 253 Gate insulating layer 254 Gate electrode 255 Source region 256 Drain region 257 LDD region 259 Insulating film 260 Insulating layer 261a Connection portion 261b Wiring 263 Insulating layer 264 First electrode 265 Partition 266 Light emitting stack 267 Second electrode 270 Thin film transistor 288 Resin 289 Desiccant 290 Polarizing plate 293 Light emitting element 294 Counter substrate 1001 Processing chamber 1002 Transfer chamber 1003 Arm 1012 First rotating plate 1013 Axis 1014a Second rotating plate 1014b Second rotating plate 1014c Second rotating plate 1014d Second rotating plate 1015a Substrate 1015b Substrate 1015c Substrate 1015d Substrate 2001 Transistor 2002 Transistor 2003 Gate signal line 2004 Source signal line 2005 Current supply line 2006 Electrode 3001 Housing 003 display unit 3004 a speaker portion 3101 body 3102 housing 3103 display unit 3104 audio input unit 3105 the audio output unit 3106 operation keys 3107 infrared port 3108 antenna 3110 body 3111 pixel portion 3112 driver IC
3113 Receiving device 3114 Film battery 3201 Main body 3202 Case 3203 Display unit 3204 Keyboard 3205 External connection port 3206 Pointing mouse 3301 Main unit 3302 Display unit 3303 Switch 3304 Operation key 3305 Infrared port 3401 Display unit 3403 Speaker unit 3404 Operation key 3405 Recording Medium insertion portion 4001 Substrate 4002 Pixel portion 4003 Signal line driver circuit 4004 Scan line driver circuit 4005 Sealing material 4006 Counter substrate 4007 Filler 4008 Thin film transistor 4010 Thin film transistor 4011 Light emitting element 4014 Wiring 4015 Wiring 4016 Connection terminal 4018 FPC
4019 Anisotropic conductive film 5541 Support body 5542 Display unit 5543 Integrated circuit chip 5544 Integrated circuit 5545 Integrated circuit 5551 Display unit 5552 Body 5553 Antenna 5554 Audio output unit 5555 Audio input unit 5556 Operation switch 5557 Operation switch 5557

Claims (39)

On the substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a hole transport layer made of an organic compound,
The light emitting layer and the hole transport layer are alternately laminated,
The hole transport layer is thinner than the light emitting layer,
The light emitting device, wherein the light emitting layer is an electron transporting light emitting layer.   2. The light-emitting device according to claim 1, wherein the light-emitting layer and the hole-transport layer are alternately stacked in an amount of 2 to n (n is a positive integer).   2. The light-emitting device according to claim 1, wherein the hole transport layer has a thickness of 1 nm to 5 nm, and the light-emitting layer has a thickness of 5 nm to 20 nm. The absolute value of the energy difference from the vacuum level of the LUMO level of the light-emitting layer according to any one of claims 1 to 3, wherein the absolute value of the energy difference from the vacuum level of the LUMO level of the hole transport layer is Greater than the value,
The absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is larger than the absolute value of the energy difference from the vacuum level of the HOMO level of the hole transport layer. . In any one of Claims 1 thru | or 3, the LUMO level of the said light emitting layer is lower than the LUMO level of the said positive hole transport layer,
The light emitting device according to claim 1, wherein a HOMO level of the light emitting layer is lower than a HOMO level of the hole transport layer. On the substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and an electron transport layer made of an organic compound,
The light emitting layer and the electron transport layer are alternately laminated,
The electron transport layer is thinner than the light emitting layer,
The light emitting device, wherein the light emitting layer is a hole transporting light emitting layer.   7. The light-emitting device according to claim 6, wherein the light-emitting layer and the electron transport layer are alternately stacked in an amount of 2 to n (n is a positive integer).   The light-emitting device according to claim 6, wherein the electron transport layer has a thickness of 1 nm to 5 nm, and the light-emitting layer has a thickness of 5 nm to 20 nm. The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer according to any one of claims 6 to 8, wherein the absolute value of the energy difference from the vacuum level of the LUMO level of the electron transport layer is Smaller than
An absolute value of an energy difference from a vacuum level of a HOMO level of the light emitting layer is smaller than an absolute value of an energy difference from a vacuum level of the HOMO level of the electron transport layer. In any one of Claims 6 thru | or 8, the LUMO level of the said light emitting layer is higher than the LUMO level of the said electron carrying layer,
The light emitting device, wherein a HOMO level of the light emitting layer is higher than a HOMO level of the electron transport layer.   11. The light-emitting device according to claim 1, wherein a buffer layer made of an organic compound and a metal compound is provided in contact with the anode. On a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, a first hole transport layer made of an organic compound, and a first hole made of an organic compound Two hole transport layers,
The light emitting layer is an electron transporting light emitting layer,
Having a first hole transport layer made of an organic compound on the anode;
On the first hole transport layer, a light emitting layer made of an organic compound and a second hole transport layer made of an organic compound are alternately laminated,
2. The light emitting device according to claim 1, wherein the second hole transport layer is thinner than the light emitting layer.   The light-emitting device according to claim 12, wherein the light-emitting layer and the second hole transport layer are alternately stacked by 2 to n (n is a positive integer).   13. The light-emitting device according to claim 12, wherein the second hole transport layer has a thickness of 1 nm to 5 nm, and the light-emitting layer has a thickness of 5 nm to 20 nm. The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer according to any one of claims 12 to 14 is the energy from the vacuum level of the LUMO level of the second hole transport layer. Greater than the absolute value of the difference,
The absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is larger than the absolute value of the energy difference from the vacuum level of the HOMO level of the second hole transport layer, Light-emitting device The LUMO level of the light emitting layer according to any one of claims 12 to 14 is lower than the LUMO level of the second hole transport layer,
The light emitting device according to claim 1, wherein a HOMO level of the light emitting layer is lower than a HOMO level of the second hole transport layer.   15. The absolute value of the energy difference between the HOMO level of the first hole transport layer and the HOMO level of the light emitting layer according to any one of claims 12 to 14 is the second hole transport layer. A light emitting device characterized in that the absolute value of the energy difference between the HOMO level and the HOMO level of the light emitting layer is smaller.   15. The absolute value of the energy difference between the work function of the anode and the HOMO level of the first hole transport layer according to claim 12, wherein the absolute value of the energy difference between the anode and the HOMO level of the first hole transport layer is the HOMO level of the second hole transport layer. A light emitting device characterized in that the absolute value of the energy difference between the level and the HOMO level of the light emitting layer is smaller.   19. The light emitting device according to claim 12, wherein a buffer layer made of an organic compound and a metal compound is provided between the first hole transport layer and the anode. On a substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, a first electron transport layer made of an organic compound, and a second made of an organic compound Having an electron transport layer,
A layer in which a light emitting layer made of an organic compound and a second electron transport layer made of an organic compound are alternately stacked;
A first electron transport layer made of an organic compound on the laminated layer;
Having a cathode on the first electron transport layer;
The light emitting device according to claim 1, wherein the second electron transporting layer is thinner than the light emitting layer.   21. The light-emitting device according to claim 20, wherein the light-emitting layer and the second electron-transport layer are alternately stacked with 2 to n (n is a positive integer).   21. The light-emitting device according to claim 20, wherein the second electron transport layer has a thickness of 1 nm to 5 nm, and the light-emitting layer has a thickness of 5 nm to 20 nm. 23. The absolute value of the energy difference from the vacuum level of the LUMO level of the light emitting layer according to any one of claims 20 to 22 is the energy difference from the vacuum level of the LUMO level of the second electron transport layer. Smaller than the absolute value of
The absolute value of the energy difference from the vacuum level of the HOMO level of the light emitting layer is smaller than the absolute value of the energy difference from the vacuum level of the HOMO level of the second hole transport layer. Light-emitting device 23. The LUMO level of the light emitting layer according to claim 20, wherein the LUMO level of the light emitting layer is higher than the LUMO level of the second electron transport layer.
The light emitting device according to claim 1, wherein a HOMO level of the light emitting layer is higher than a HOMO level of the second hole transport layer.   23. The absolute value of the energy difference between the HOMO level of the first electron transporting layer and the HOMO level of the light emitting layer according to any one of claims 20 to 22, wherein the HOMO level of the second electron transporting layer is And a HOMO level of the light emitting layer is smaller than an absolute value of an energy difference.   23. The absolute value of the energy difference between the work function of the cathode and the HOMO level of the first electron transport layer according to claim 20, wherein an absolute value of an energy difference between the work function of the cathode and the HOMO level of the second electron transport layer is A light emitting device characterized by being smaller than an absolute value of an energy difference from a HOMO level of the light emitting layer.   27. The light-emitting device according to claim 20, wherein a buffer layer made of an organic compound and a metal compound is provided between the first electron transport layer and the cathode. On the substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a carrier transport layer made of an organic compound,
The light emitting layer and the carrier transport layer are alternately laminated,
The thickness of the carrier transport layer is a method for manufacturing a light emitting device thinner than the thickness of the light emitting layer,
The substrate is provided on the evaporation source of the carrier transport material and the evaporation source of the light emitting material,
A first shutter that can be opened and closed is provided between the evaporation source of the carrier transport material and the substrate;
A second shutter capable of opening and closing is provided between the evaporation source of the luminescent material and the substrate;
A method for manufacturing a light-emitting device, wherein the light-emitting layer and the carrier transport layer are alternately stacked by opening and closing the first and second shutters. In Claim 28, when the first shutter is open, the second shutter is closed to deposit the carrier transport material on the substrate,
A light emitting device characterized in that when the second shutter is open, the first shutter is closed, the light emitting material is deposited on the substrate, and the light emitting layer and the carrier transport layer are alternately stacked. Manufacturing method.   29. The light emitting layer and the carrier transport layer are alternately stacked by controlling opening and closing of the first and second shutters, a deposition rate of the light emitting material, and a deposition rate of the carrier transport material. A method for manufacturing a light-emitting device. On the substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a carrier transport layer made of an organic compound,
The light emitting layer and the carrier transport layer are alternately laminated,
The thickness of the carrier transport layer is a method for manufacturing a light emitting device thinner than the thickness of the light emitting layer,
The substrate is provided on a first rotating plate;
The first rotating plate is provided on the evaporation source of the light emitting material and the evaporation source of the carrier transport material,
When the first rotating plate rotates and the distance between the evaporation source of the light emitting material and the substrate and the distance between the evaporation source of the carrier transport material and the substrate change, the light emitting layer and the carrier A method for manufacturing a light-emitting device, characterized in that transport layers are alternately stacked. 32. The light emission according to claim 31, wherein the first rotating plate rotates and the distance between the evaporation source of the light emitting material and the substrate is shorter than the distance between the evaporation source of the carrier transport material and the substrate. More material is deposited than the carrier transport material to form the light emitting layer,
When the distance between the evaporation source of the carrier transporting material and the substrate is shorter than the distance between the evaporation source of the light emitting material and the substrate, the carrier transporting layer is deposited more than the light emitting material and the carrier transporting layer is deposited. A method for manufacturing a light-emitting device, wherein:   32. The method for manufacturing a light-emitting device according to claim 31, wherein the light-emitting layer and the carrier transport layer are alternately stacked while controlling a deposition rate of the light-emitting material and a deposition rate of the carrier transport material.   32. The shutter according to claim 31, wherein a shutter that can be opened and closed is provided between the carrier transport layer and the substrate, and the rotation of the first rotating plate is controlled and the opening and closing of the shutter is controlled. A method for manufacturing a light-emitting device, wherein carrier transport layers are alternately stacked. In Claim 31, the second rotating plate is provided on the first rotating plate, the substrate is provided on the second rotating plate,
A method for manufacturing a light-emitting device, wherein the first rotating plate and the second rotating plate have different central axes and rotate independently of each other. On the substrate, an anode, a cathode facing the anode, a light emitting layer made of an organic compound provided between the anode and the cathode, and a carrier transport layer made of an organic compound,
The light emitting layer and the carrier transport layer are alternately laminated,
The thickness of the carrier transport layer is a method for manufacturing a light emitting device thinner than the thickness of the light emitting layer,
The substrate is provided on the evaporation source of the carrier transport material and the evaporation source of the light emitting material,
A rotatable first mask is provided between the evaporation source of the luminescent material and the substrate;
A rotatable second mask is provided between the evaporation source of the carrier transport material and the substrate;
A method for manufacturing a light-emitting device, wherein the light-emitting layer and the carrier transport layer are alternately stacked by controlling rotation of the first and second masks.   37. The method for manufacturing a light-emitting device according to claim 36, wherein the first and second masks are provided with slits or holes. 38. The hole or slit of the second mask according to claim 37, wherein the hole or slit of the second mask is between the evaporation source of the light emitting material and the substrate. Depositing the luminescent material on the substrate without being present between the substrates;
When the hole or slit of the second mask is between the evaporation source of the carrier transport material and the substrate, the hole or slit of the first mask exists between the light emitting material and the substrate. The light-emitting device manufacturing method, wherein the light-emitting layer and the carrier-transporting layer are alternately stacked by vapor-depositing the carrier-transporting material on the substrate.   37. The method for manufacturing a light-emitting device according to claim 36, wherein the light-emitting layer and the carrier transport layer are alternately stacked by controlling a deposition rate of the light-emitting material and a deposition rate of the carrier transport material.

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