CN116978894A - a display device - Google Patents
a display device Download PDFInfo
- Publication number
- CN116978894A CN116978894A CN202210417950.9A CN202210417950A CN116978894A CN 116978894 A CN116978894 A CN 116978894A CN 202210417950 A CN202210417950 A CN 202210417950A CN 116978894 A CN116978894 A CN 116978894A
- Authority
- CN
- China
- Prior art keywords
- light
- layer
- emitting unit
- light emitting
- emitting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10H—INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS
- H10H20/00—Individual inorganic light-emitting semiconductor devices having potential barriers, e.g. light-emitting diodes [LED]
- H10H20/80—Constructional details
- H10H20/85—Packages
- H10H20/851—Wavelength conversion means
-
- H10W90/00—
Landscapes
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Abstract
The invention discloses a display device, comprising: the light-emitting units comprise light-emitting chips, at least part of the light-emitting units also comprise a light-transmitting matrix layer, and the light-emitting chips are positioned on one side, away from the driving substrate, of the light-emitting chips; the transparent substrate layer comprises a plurality of nanopores, and the nanopores of the transparent substrate layer of part of the light-emitting units are filled with color conversion materials. The luminous units with lower luminous efficiency are replaced by the luminous chip, the light emitting side of the luminous chip is provided with the light transmitting matrix layer, and the color conversion material is filled in the nano holes of the light transmitting matrix layer, so that the luminous efficiency of each luminous unit in the display device can be improved. The light-transmitting matrix layer is independently arranged for forming the nano holes, so that the influence on the light-emitting efficiency of the light-emitting chip caused by the fact that the nano holes are directly formed in the light-emitting chip can be avoided. The nanopores may also improve light extraction efficiency.
Description
Technical Field
The invention relates to the technical field of display, in particular to a display device.
Background
The self-luminous display device has the advantages of no need of arranging a backlight module, simple device structure, lower dark field brightness and the like, and becomes a research focus in the display field.
The light emitting diode (Light Emitting Diode, abbreviated as LED) display technology refers to that a light emitting diode is used as a light emitting device directly for image display. LED display devices typically use three primary color light emitting chips for full color display.
The three-primary-color light-emitting chip is generally made of different semiconductor materials, and particularly the AlGaInP-based red light chip has low efficiency, crisp texture and poor yield, and particularly the efficiency is sharply reduced when the size is reduced to the micron level. In addition, the refractive index of the epitaxial material of the light-emitting chip is greatly different from that of the air and the substrate material, light emitted by the light-emitting chip is easy to generate total reflection at the interface of the high refractive index material and the low refractive index material, so that light generated by the light-emitting chip propagates in a waveguide mode in the epitaxial layer film and is finally reabsorbed by the epitaxial layer, and the light extraction efficiency of the light-emitting chip is limited.
Disclosure of Invention
In some embodiments of the present invention, a display device includes: the light-emitting unit that drive base plate and a plurality of and drive base plate electricity are connected, and the light-emitting unit all includes: and a light emitting chip electrically connected with the driving substrate near one side of the driving substrate, wherein at least part of the light emitting units further comprise: the light-transmitting matrix layer is positioned at one side of the light-emitting chip, which is away from the driving substrate; the transparent substrate layer comprises a plurality of nanopores, and the nanopores of the transparent substrate layer of part of the light-emitting units are filled with color conversion materials. The luminous units with lower luminous efficiency are replaced by the luminous chip, the light emitting side of the luminous chip is provided with the light transmitting matrix layer, and the color conversion material is filled in the nano holes of the light transmitting matrix layer, so that the luminous efficiency of each luminous unit in the display device can be improved. The light-transmitting matrix layer is independently arranged for forming the nano holes, so that the influence on the light-emitting efficiency of the light-emitting chip caused by the fact that the nano holes are directly formed in the light-emitting chip can be avoided. After the emergent light of the light-emitting chip is incident to the light-transmitting matrix layer, the light rays can be emitted to all directions through the nano holes due to the nano distribution, so that the total reflection condition can be destroyed when the light is emergent outwards, and the light extraction efficiency is improved.
In some embodiments of the present invention, the color of light emitted from the light emitting chips included in the light emitting units may be different, and each light emitting unit is used as a sub-pixel. The red light emitting unit, the green light emitting unit and the blue light emitting unit are repeatedly arranged in a set order, wherein the red light emitting unit is used as a red sub-pixel, the green light emitting unit is used as a green sub-pixel, the blue light emitting unit is used as a blue sub-pixel, and one pixel unit is formed by one red light emitting unit, one green light emitting unit and one blue light emitting unit which are adjacent. The green light emitting unit and the blue light emitting unit include only light emitting chips. The red light emitting unit comprises a light emitting chip and a light transmitting substrate layer, and red conversion materials are filled in the nano holes of the light transmitting substrate layer. The light emitting chips included in the green light emitting unit are green light LEDs, the light emitting chips included in the blue light emitting unit and the red light emitting unit are blue light LED chips, the green light LED chips emit green light, the blue light LED chips emit blue light, and the blue light emitted by the blue light LED chips excites the red conversion material to emit red light, so that three primary colors of light are formed, and full-color display is realized.
In some embodiments of the present invention, the light emitting chip is a blue LED chip for emitting blue light. Each of the light emitting units serves as one subpixel, and in order to realize full color display, the light emitting units are divided into a red light emitting unit, a green light emitting unit, and a blue light emitting unit. The red light emitting unit, the green light emitting unit and the blue light emitting unit are repeatedly arranged in a set order, wherein the red light emitting unit is used as a red sub-pixel, the green light emitting unit is used as a green sub-pixel, the blue light emitting unit is used as a blue sub-pixel, and one pixel unit is formed by one red light emitting unit, one green light emitting unit and one blue light emitting unit which are adjacent. The nanometer holes of the light-transmitting matrix layer of the red light-emitting unit are filled with red conversion materials, and the red conversion materials are used for emitting red light under the excitation of blue light emitted by the light-emitting chip; the nanometer holes of the light-transmitting matrix layer of the green light-emitting unit are filled with a green conversion material, and the green conversion material is used for emitting green light under the excitation of blue light emitted by the light-emitting chip; the nano holes of the light-transmitting matrix layer of the blue light-emitting unit can be not filled or filled with a transparent medium, so that the blue light-emitting unit emits blue light, and three primary colors of light are formed, thereby realizing full-color display.
In some embodiments of the present invention, a light emitting chip includes: an n-type doped layer, a light emitting layer, a p-type doped layer, a dielectric layer and an electrode.
In some embodiments of the present invention, the n-type doped layer is an n-type doped GaN layer, the p-type doped layer is a p-type doped GaN layer, and the light-transmitting substrate layer is an n-type heavily doped GaN layer, so that a low-cost electrochemical etching method can be used to form a nanopore in the n-type heavily doped GaN layer.
In some embodiments of the present invention, a first filter layer is disposed between the n-type heavily doped GaN layer and the n-type doped GaN layer. The first filter layer serves on the one hand as an electrical isolation between the n-type heavily doped GaN layer and the n-type doped GaN layer, and on the other hand also serves to transmit blue light and reflect red light and green light.
In some embodiments of the present invention, when only the red light emitting unit includes the light emitting chip and the light transmitting substrate layer, the first filter layer is disposed in the red light emitting unit, and the first filter layer can transmit blue light emitted from the light emitting chip, and reflect red light stimulated by the red conversion material to a side away from the driving substrate, so as to improve light extraction efficiency.
In some embodiments of the present invention, when each light emitting unit includes a light emitting chip and a light transmitting substrate layer, a first filter layer is disposed in each light emitting unit, where the first filter layer can transmit blue light emitted from the light emitting chip, and can reflect red light and green light stimulated and emitted by the red light emitting unit and the green light emitting unit to a side deviating from the driving substrate, so as to improve light extraction efficiency.
In some embodiments of the present invention, after the epitaxial layer of the light emitting chip is formed, a plurality of light emitting units arranged in an array are formed by etching, and the sidewalls of the light emitting units have a certain inclination angle.
In some embodiments of the invention, the display device further comprises a passivation layer. The passivation layer is positioned on the surface of at least part of the light emitting units facing away from the side of the driving substrate and the side wall of each light emitting unit. After the epitaxial layer is etched to form the light-emitting unit, a passivation layer is formed on the surface of the light-emitting unit because the side wall generates defects, so that the side wall defects can be reduced, non-radiative recombination is reduced, and the light-emitting efficiency is increased.
In some embodiments of the present invention, the display device further includes a second filter layer, where the second filter layer is located on the passivation layer on the surface and the sidewall of each red light emitting unit or each red light emitting unit and each green light emitting unit facing away from the side of the driving substrate. The second filter layer is used for transmitting red light and green light and reflecting blue light. Since the conversion efficiency of the color conversion material for the blue light emitted from the light emitting chip is not 100%, the direct emission of the unused blue light may cause a problem of color shift between the red light emitting unit and the green light emitting unit. Therefore, the second filter layer is arranged on the light emitting side of the red light emitting unit and the green light emitting unit, the unused blue light can be reflected back to the light emitting unit to excite the color conversion material again, and the light emitting efficiency of the red light emitting unit and the green light emitting unit is improved. The second filter layer positioned in the isolation groove also serves as an isolation layer, on one hand, the effect of reflecting blue light by the second filter layer can prevent the blue light from emitting crosstalk to the adjacent light-emitting units, and on the other hand, the loss of the blue light can be reduced, and the light emitting efficiency is improved. The isolation property of the second filter layer achieved by reflection can also avoid the problem of reduced device performance due to light absorption and heating.
In some embodiments of the present invention, blue light emitted from a light emitting layer in a light emitting chip is emitted in all directions, and a part of the blue light is incident into a nanopore, and is converted into red light or green light after exciting a color conversion material. The converted red light or green light is emitted to all directions, wherein one part of the red light or green light is emitted outwards through the second filter layer, and the other part of the red light or green light emitted to one side of the light emitting chip is reflected by the first filter layer and then outwards emitted. Blue light which is not completely converted cannot pass through the second filter layer, is reflected back to the light-emitting unit by the second filter layer, passes through the first filter layer and the epitaxial layer of the light-emitting chip, is reflected by the electrode, and excites the color conversion material again to be converted into red light or green light to be emitted outwards until the blue light is completely converted. The blue light emitted from the side surface of the light-emitting chip is reflected by the second filter layer at the side wall and then returns to the light-emitting unit, and is converted into red light or green light through the excitation color conversion material and then emitted outwards. Therefore, only the converted red light or green light can be emitted outwards from the light-emitting unit, the conversion efficiency of the blue light is improved, the emission efficiency of the red light or green light is improved, and the light loss is reduced.
In some embodiments of the present invention, the blue light emitting unit is disposed adjacent to the red light emitting unit and the green light emitting unit, so that a sidewall of the blue light emitting unit is adjacent to the second filter layer at the periphery of the red light emitting unit or the green light emitting unit. The nano holes in the blue light-emitting unit are not filled or filled with transparent media, blue light emitted by the light-emitting chip is emitted in all directions, the blue light emitted from the front face is directly emitted outwards, the blue light emitted from the side face is reflected by the second filter layer at the side wall and then changes direction, and finally emitted from the front face of the blue light-emitting unit after multiple reflections, so that the light-emitting efficiency of the front face of the blue light-emitting unit can be enhanced, and crosstalk is reduced.
In some embodiments of the present invention, the first filter layer and the second filter layer may each be a Bragg reflection layer.
In some embodiments of the present invention, the display device further includes: and a bonding layer and a package substrate. The bonding layer is positioned on the surface of one side of the second filter layer, which is away from the driving substrate. The packaging substrate is positioned on the surface of one side of the bonding layer, which is away from the driving substrate.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic cross-sectional structure of a display device according to an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional structure of a pixel unit according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a cross-sectional structure of a pixel unit according to an embodiment of the invention;
fig. 4 is a schematic cross-sectional structure of a red (green) light emitting unit according to an embodiment of the present invention;
fig. 5 is a schematic cross-sectional structure of a blue light emitting unit according to an embodiment of the present invention.
The light-emitting diode comprises a 1-driving substrate, a 2-light-emitting unit, a 2 r-red light-emitting unit, a 2 b-blue light-emitting unit, a 2 g-green light-emitting unit, a 3-passivation layer, a 4-second filter layer, a 5-bonding layer, a 6-packaging substrate, a 21-light-emitting chip, a 22-light-transmitting matrix layer, an h-nanopore, a 23-first filter layer, a 211-n type doped layer, a 212-light-emitting layer, a 213-p type doped layer, a 214-medium layer, a 215-electrode and a c-substrate.
Detailed Description
In order that the above objects, features and advantages of the invention will be readily understood, a further description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. However, the exemplary embodiments can be embodied in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus a repetitive description thereof will be omitted. The words expressing the positions and directions described in the present invention are described by taking the drawings as an example, but can be changed according to the needs, and all the changes are included in the protection scope of the present invention. The drawings of the present invention are merely schematic representations of relative positional relationships and are not intended to represent true proportions.
The self-luminous display device has the advantages of no need of arranging a backlight module, simple device structure, lower dark field brightness and the like, and becomes a research focus in the display field.
The light emitting diode (Light Emitting Diode, abbreviated as LED) display technology refers to that a light emitting diode is used as a light emitting device directly for image display. Micro LEDs (Micro Light Emitting Diode, abbreviated as Micro LEDs) refer specifically to miniaturized LED chips. Typically, the size of Micro LEDs is in the order of microns, e.g., micro LEDs are less than 100 μm in size. When the size of the Micro LED chip is reduced to the pixel level, the Micro LED can be directly used as a light-emitting unit for image display.
Current LED display devices generally use tricolor light emitting chips for full color display. The AlGaInP-based red LED chip is low in efficiency, crisp in texture and poor in yield compared with a GaN-based green LED chip and a GaN-based blue LED chip, and particularly when the size is reduced to a micron level, the efficiency is rapidly reduced. The GaN-based green light LED chip and the GaN-based blue light LED chip have higher efficiency and yield and lower manufacturing cost. Therefore, the blue LED chip and the color conversion material can be combined to generate red light, so that the cost can be reduced, and higher luminous efficiency can be realized.
The conventional method is to coat the color conversion material on the surface of the blue light LED chip, and the shape of the color conversion material is not easy to control, so that blue light is difficult to be completely converted, and color cast exists. If the filter is used for filtering, light emitted from the blue LED chip, which is one of the three primary colors of light, is suppressed, resulting in a decrease in efficiency.
In addition, the refractive index of the epitaxial material of the LED is greatly different from that of the air and the substrate material, and the total reflection of the emergent light of the light-emitting layer of the LED chip occurs at the interface of the high refractive index material and the low refractive index material, so that the emergent light of the light-emitting layer of the LED chip propagates in a waveguide mode in the epitaxial layer film and is finally reabsorbed by the epitaxial layer, thereby limiting the light extraction efficiency of the LED chip.
In order to overcome the above-mentioned problems, an embodiment of the present invention provides a display device, and fig. 1 is a schematic cross-sectional structure of the display device according to the embodiment of the present invention.
As shown in fig. 1, a display device provided in an embodiment of the present invention includes: the substrate 1 and the light emitting unit 2 are driven.
The drive substrate 1 is located at the bottom of the display device and is usually sized to fit the overall size of the display device, the size of the drive substrate 1 being slightly smaller than the size of the display device.
In some embodiments, the display device may also include a plurality of driving substrates 1, where the driving substrates 1 commonly provide driving signals through a stitching manner. In order to avoid the optical problem caused by the splicing of the driving substrates 1, the splice between the adjacent driving substrates 1 is made as small as possible, and even seamless splicing is realized.
The driving substrate 1 may have the same shape as the entire shape of the display device, and may be generally rectangular or square. When the display device is a special-shaped display device, the shape of the driving substrate may be adaptively set to other shapes, which is not limited herein.
The driving substrate 1 is used to supply a driving signal to the light emitting unit 2. Typically, a circuit board or an array substrate may be employed.
The circuit board may be a printed circuit board (Printed Circuit Board, abbreviated as PCB), and when applied to a flexible display, a flexible circuit board (Flexible Printed Circuit, abbreviated as FPC) may be used, which is not limited herein.
The array substrate can be manufactured by adopting the current mature thin film technology, and the specific structure can be referred to the array substrate of the LCD or OLED display device in the prior art, and the detailed description is omitted here.
The light emitting unit 2 is located above the driving substrate 1 and electrically connected to the driving substrate 1, and the driving substrate 1 is used for providing a driving signal to the light emitting unit 2, so as to control the brightness of the light emitting unit 2, and realize image display.
In the embodiment of the present invention, as shown in fig. 1, each light emitting unit 2 includes: the light emitting chip 21, at least part of the light emitting unit 2 further includes: a light transmissive matrix layer 22.
The light emitting chip 21 is positioned at one side close to the driving substrate 1 and is electrically connected with the driving substrate 1; the driving substrate 1 may supply driving signals to each of the light emitting chips 21, respectively, to thereby control the light emitting luminance of each of the light emitting chips 21, respectively.
The light emitting chip 21 may be an LED chip, a Mini LED chip, or a Micro LED chip. The sizes of the Mini LED chip and the Micro LED chip can reach the sub-millimeter or micrometer level, and the size of the Mini LED chip is larger than that of the Micro LED chip. When the light emitting device is applied to different application scenes and the requirements on pixel levels are different, light emitting chips with different sizes can be adopted according to the implementation conditions, and the light emitting device is not limited.
At least part of the light emitting unit further comprises a light transmissive matrix layer 22. The light-transmitting matrix layer 22 is positioned on one side of the light-emitting chip 21 away from the driving substrate 1; the light-transmitting substrate layer 22 includes a plurality of nanopores h therein. The light-transmitting substrate layer 22 may be made of a light-transmitting material, and the light-transmitting substrate layer 22 is located on the light-emitting side of the light-emitting unit 2. The embodiment of the invention provides a transparent substrate layer 22 on the light emitting side of the light emitting chip 21 to form a nano hole h in the transparent substrate layer 22. Different materials may be selected as the light-transmitting substrate layer 22 according to the fabrication process of the nanopores h.
In the embodiment of the present invention, in order to improve the light emitting efficiency of a part of the light emitting units and for full color display, the nano holes h of the light transmitting substrate layer 22 are filled with the color conversion material so that the color conversion material emits light of other colors under the excitation of the emitted light of the light emitting chip 21.
The luminous efficiency of each luminous unit in the display device can be improved by replacing the luminous unit with lower luminous efficiency in the display device with the light-transmitting substrate layer arranged on the light-emitting side of the luminous chip and filling the color conversion material in the nano holes of the light-transmitting substrate layer.
The light-transmitting substrate layer 22 is separately provided for forming the nano-holes h, so that the influence on the light-emitting efficiency of the light-emitting chip caused by directly forming the nano-holes in the light-emitting chip can be avoided. After the emergent light of the light-emitting chip 21 is incident on the light-transmitting substrate layer, the light can be emitted to all directions through the nano holes due to the distribution of the nano h, so that the total reflection condition can be destroyed when the light is emergent outwards, and the light extraction efficiency is improved.
In specific implementation, the nano holes h can be manufactured by electrochemical etching, inductively coupled plasma etching (Inductively Coupled Plasma Etch, abbreviated as ICPE), electron beam exposure (Electron Beam Lithography, abbreviated as EBL) etching and the like, and can be regular or irregular, uniformly distributed or regional distributed, the diameter of the nano holes h can be nano-scale, can be between 1nm and 1000nm, even larger, and the depth of the nano holes h can be between 0.1 μm and 10 μm, which is not limited.
The color conversion material filled in the nano-pores can be a fluorescent material or a quantum dot material. The quantum dot material can realize higher color gamut, and can be specifically manufactured by methods such as ink-jet printing, atomization spraying, spin coating, photolithography and the like, and then is conveyed into the nano holes by technologies such as vacuum, vibration, ultrasound, cavitation, pressure, electrostatic adsorption and the like.
The quantum dot material may be perovskite quantum dots, cdSe colloid quantum dots, znS, znSe, cdSe, inP, cdS, pbS, inAs, gaP, gaAs, etc., and is not limited herein.
Fig. 2 is a schematic cross-sectional structure of a pixel unit according to an embodiment of the present invention.
In some embodiments, the colors of light emitted from the light emitting chips included in the light emitting units may be different, each light emitting unit being one sub-pixel, and in order to realize full color display, the light emitting units are divided into a red light emitting unit 2r, a green light emitting unit 2g, and a blue light emitting unit 2b as shown in fig. 2. The red light emitting unit 2r, the green light emitting unit 2g, and the blue light emitting unit 2b are generally repeatedly arranged in a set order, with the red light emitting unit 2r as a red sub-pixel, the green light emitting unit 2g as a green sub-pixel, and the blue light emitting unit 2b as a blue sub-pixel, and adjacent one red light emitting unit 2r, one green light emitting unit 2g, and one blue light emitting unit 2b constitute one pixel unit.
The green light emitting unit 2g and the blue light emitting unit 2b include only the light emitting chip 21 and the substrate c. The red light emitting unit 2r includes a light emitting chip 21 and a light transmitting matrix layer 22 on a side of the light emitting chip facing away from the driving substrate 1, and red conversion material is filled in the nano holes h of the light transmitting matrix layer 22.
The light emitting chip included in the green light emitting unit 2g is a green light emitting chip for emitting green light, the light emitting chip included in the blue light emitting unit 2b is a blue light emitting chip for emitting blue light, and the light emitting chip included in the red light emitting unit 2r is a blue light emitting chip for emitting blue light. Therefore, the green light-emitting chip emits green light, the blue light-emitting chip emits blue light, and the blue light emitted by the blue light-emitting chip excites the red conversion material to emit red light, so that three primary colors of light are formed, and full-color display is realized.
In specific implementation, the green light emitting chip may be a green light LED chip, the blue light emitting chip may be a blue light LED chip, and the substrate c on the surfaces of the green light LED chip and the blue light LED chip may be a substrate for manufacturing the blue light LED chip and the green light LED chip, for example, the substrate c may be a sapphire substrate. Only the red light emitting unit 2r is set in such a way that the blue LED chip excites the red conversion material, so that the light emitting units of each color have higher light emitting efficiency.
The red conversion material can be a red quantum dot material, the luminous wavelength of the red quantum dot is 600 nm-700 nm, and the luminous wavelength of the blue LED chip is 400 nm-480 nm. The red quantum dots are filled in the nano holes, and the stimulated red light is emitted to various directions, so that the total reflection condition of the light emitted outwards from the device is destroyed, and the light extraction efficiency is improved.
Fig. 3 is a schematic diagram of a cross-sectional structure of a pixel unit according to an embodiment of the invention.
In some embodiments, the color of the emitted light of the light emitting chip 21 of each light emitting unit may be the same, and each light emitting unit 2 serves as one sub-pixel, and in order to realize full color display, the light emitting units are divided into a red light emitting unit 2r, a green light emitting unit 2g, and a blue light emitting unit 2b as shown in fig. 3. The red light emitting unit 2r, the green light emitting unit 2g, and the blue light emitting unit 2b are generally repeatedly arranged in a set order, with the red light emitting unit 2r as a red sub-pixel, the green light emitting unit 2g as a green sub-pixel, and the blue light emitting unit 2b as a blue sub-pixel, and adjacent one red light emitting unit 2r, one green light emitting unit 2g, and one blue light emitting unit 2b constitute one pixel unit.
The red light emitting unit 2r, the green light emitting unit 2g, and the blue light emitting unit 2b each include a light emitting chip 21 and a light transmitting matrix layer 22 on a side of the light emitting chip facing away from the drive substrate 1.
The light emitting chips included in the red light emitting unit 2r, the green light emitting unit 2g, and the blue light emitting unit 2b are all blue light emitting chips for emitting blue light, and for example, blue LED chips may be used. The red conversion material is filled in the nano holes h of the light-transmitting matrix layer of the red light-emitting unit 2r so that the red conversion material emits red light under the excitation of blue light emitted by the light-emitting chip 21; the nano holes h of the light-transmitting substrate layer of the green light-emitting unit 2g are filled with a green conversion material so that the green conversion material emits green light under excitation of blue light emitted from the light-emitting chip 21. The nano holes h of the light-transmitting substrate layer of the blue light-emitting unit 2b may not be filled or filled with a transparent medium, so that the blue light-emitting unit 2b emits blue light, thereby forming tri-primary color light and realizing full-color display.
In the embodiment of the invention, the red conversion material may be a red quantum dot material, and the green conversion material may be a green quantum dot. The luminous wavelength of the red quantum dots is 600 nm-700 nm, the luminous wavelength of the green quantum dots is 490 nm-580 nm, and the luminous wavelength of the blue LED chip is 400 nm-480 nm. The red quantum dots and the green quantum dots are filled in the nano holes, and the stimulated emission red light and the stimulated emission green light emit towards all directions; and blue light emitted by the blue LED chip in the blue light-emitting unit is emitted to all directions after passing through the nanopore, so that the total reflection condition of light emitted outwards from the device can be destroyed, and the light extraction efficiency is improved.
It should be noted that the display device provided in the embodiment of the present invention may adopt at least two structures.
In one of the structures, as shown in fig. 2, a green light emitting unit employs a green LED chip; the blue light emitting unit adopts a blue light LED chip; only the red light-emitting unit adopts a structure that a blue light LED chip is overlapped with a light-transmitting matrix layer, and red conversion materials are filled in the nano holes of the light-transmitting matrix layer. This is because the red LED chip has low luminous efficiency relative to the green LED chip and the blue LED chip. The adoption of the structure can improve the luminous efficiency of the red luminous unit. At this time, the green light emitting unit, the blue light emitting unit and the red light emitting unit are required to be manufactured separately and transferred onto the driving substrate separately.
In another structure, as shown in fig. 3, the red light emitting unit, the green light emitting unit and the blue light emitting unit are all stacked by using blue LED chips to form a light-transmitting matrix layer, and the nano holes of the light-transmitting matrix layers of the red light emitting unit and the green light emitting unit are filled with a color conversion material. Since the light emitting units of each color adopt the same light emitting chip, each light emitting unit can be manufactured together, cut according to the pixel unit or the plurality of pixel units, and transferred onto the driving substrate. In this case, the number of times of mass transfer can be reduced, and the transfer efficiency can be improved. And the space between the light emitting units in the pixel units is further reduced so as to set more pixel units in a limited space and improve the display resolution.
When a single light emitting unit is used as a light emitting device, i.e., a structure as shown in fig. 2, the lateral dimension of the light emitting device is about 4 μm to 200 μm; when a pixel unit composed of one red light emitting unit 2r, one green light emitting unit 2g, and one blue light emitting unit 2b is used as a light emitting device, that is, a structure as shown in fig. 3 is adopted, the lateral dimension of the light emitting device is about 10 μm to 600 μm.
Fig. 4 is a schematic cross-sectional structure of a red (green) light emitting unit according to an embodiment of the present invention.
As shown in fig. 2 to 4, the light emitting chip 21 includes, regardless of the display panel structure employed: an n-doped layer 211, a light emitting layer 212, a p-doped layer 213, a dielectric layer 214, and an electrode 215.
An n-doped layer 211, a light emitting layer 212 and a p-doped layer 213 are arranged in a stack and grown on a suitable substrate using LED epitaxy techniques. The n-type doped layer 211 and the p-type doped layer 213 may be formed by n-type doping and p-type doping respectively using the same material. The thickness of the n-doped layer 211 is about 2 μm to 4 μm and the thickness of the p-doped layer 213 is about 100nm to 1000nm. The light emitting layer 212 may employ multiple quantum wells, which is advantageous for improving light emitting efficiency. The thickness of the light emitting layer 212 is about 100nm to 500nm.
Light emitting layer 212 and p-doped layer 213 expose a portion of the n-type dopingAnd a layer 211 for forming an electrode. A dielectric layer 214 is formed on the exposed surfaces of the n-doped layer 211 and the p-doped layer 213 before forming the electrodes. The dielectric layer 214 serves to protect the non-electrode region from the external environment and to prevent shorting between the electrodes. Dielectric layer 214 may be formed of SiO 2 、AlN、Al 2 O 3 One or more materials in AlON are manufactured by atomic layer deposition or plasma chemical vapor deposition. The thickness of dielectric layer 214 is approximately 100nm to 1000nm.
The dielectric layer 214 includes two through holes exposing a portion of the n-type doped layer 211 and a portion of the p-type doped layer 213, respectively; the two electrodes 215 are respectively in contact with the exposed n-type doped layer 211 and the p-type doped layer 213 through two through holes. The electrode connected with the n-type doped layer 211 is an n-electrode, the electrode connected with the p-type doped layer 213 is a p-electrode, the n-electrode can be made of Ti/Al/Ni/Au metal, the p-electrode can be made of Ni/Au metal, and the materials for manufacturing the electrode can comprise, but are not limited to, cr, ti, ni, au, sn, sn, al, au, pt and other metals or combinations.
When the structure shown in fig. 2 is adopted, the light emitting chips in the red light emitting unit 2r and the light emitting chips in the blue light emitting unit adopt blue LED chips, and the light emitting chips in the green light emitting unit adopt green LED chips; when the structure shown in fig. 3 is employed, the blue LED chips are employed for the light emitting chips 21 in all the light emitting units. In the embodiment of the invention, the blue light LED chip and the green light LED chip are both GaN-based. Taking a blue LED chip as an example, the n-doped layer 211 may be an n-doped GaN layer with a doping concentration ranging from about 2×10 17 /cm 3 ～8×10 18 /cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The p-doped layer 213 may be a p-doped GaN layer with a doping concentration ranging from about 1×10 19 /cm 3 ～1×10 20 /cm 3 . The light-emitting layer 212, i.e. the multiple quantum well layer is formed by alternately growing an InGaN quantum well layer and a GaN barrier layer, electrons and holes generate radiation recombination in the InGaN/GaN multiple quantum well to emit photons, and the thickness, the composition and the period of the well layer and the barrier layer can be regulated and controlled to emit light with a wavelength of 400 nm-480 nm.
Further, considering the production cost, the material system used for the light emitting chip, and whether the material is convenient for forming the nano-pores. In the embodiment of the present invention, the light-transmitting substrate layer 22 may be an n-type heavily doped GaN layer, so that the nanopore h may be formed in the n-type heavily doped GaN layer by using a low-cost electrochemical etching method.
Specifically, the doping concentration of the n-type heavily doped GaN layer ranges from about 2×10 18 /cm 3 ～1×10 20 /cm 3 . The thickness of the n-type heavily doped GaN layer is about 0.1 μm to 10 μm.
The GaN in the embodiment of the present invention may be nonpolar GaN, semipolar GaN or c-plane GaN, which is not limited herein.
The n-type raw doping of GaN is beneficial to forming a nano hole h, but is not beneficial to ohmic contact and luminescence; and the doping concentration of the n-type doped GaN layer in the light emitting chip cannot be too high, otherwise, the light emitting efficiency of the light emitting chip is reduced due to unbalanced transportation capability of n-type carriers and p-type carriers.
In view of this, in the embodiment of the present invention, as shown in fig. 2 to 4, the first filter layer 23 is disposed between the n-type heavily doped GaN layer (22) and the n-type doped GaN layer (211). The first filter layer 23 serves on the one hand as an electrical isolation between the n-type heavily doped GaN layer (22) and the n-type doped GaN layer (211), and on the other hand also serves to transmit blue light, reflecting red light and green light.
When the structure shown in fig. 2 is adopted, only the first filter layer 23 is disposed in the red light emitting unit 2r, the first filter layer 23 can transmit blue light emitted from the light emitting chip 21, and simultaneously, red light stimulated and emitted by the red conversion material is reflected to the side deviating from the driving substrate, so that the light extraction efficiency is improved.
When the structure shown in fig. 3 is employed, the first filter layer 23 is provided in each light emitting unit. The first filter layer 23 can transmit blue light emitted by the light emitting chip 21, and can reflect red light and green light stimulated and emitted by the red light emitting unit 2r and the green light emitting unit 2g to one side away from the driving substrate, so that light extraction efficiency is improved.
When the structure shown in fig. 2 is adopted, the green light-emitting unit 2g and the blue light-emitting unit 2b both directly emit light by using light-emitting chips, and the manufacturing method is different from that of the red light-emitting unit 2 r. As shown in fig. 2, for the green light emitting unit 2g and the blue light emitting unit 2b, the light emitting unit further includes a substrate c on a side of the light emitting chip 21 facing away from the driving substrate, and the substrate c may be a substrate when manufacturing the blue LED chip and the green LED chip, for example, the substrate c may be a sapphire substrate.
When the structure shown in fig. 3 is adopted, each light emitting unit is fabricated together. In fig. 2, the red light emitting units 2r are also usually manufactured in a plurality of at once and then cut into a plurality of red light emitting units. Therefore, in the manufacturing process, after the epitaxial layer of the light emitting chip is formed, a plurality of light emitting units 2 arranged in an array are formed by etching, and isolation grooves are formed between adjacent light emitting units by etching. As shown in fig. 3, the width of the isolation groove U on the side close to the driving substrate 1 is smaller than the width of the isolation groove U on the side far away from the driving substrate 1, so that the side wall of the light emitting unit 2 has a certain inclination angle, and the isolation groove U has a structure with a wide upper part and a narrow lower part.
The isolation grooves U are filled with an insulating material to isolate the light emitting units 2 from each other. In an embodiment of the present invention, as shown in fig. 3, the display device further includes a passivation layer 3. The passivation layer 3 is formed not only on the light emitting side surface of the light emitting units 2 but also in the isolation groove U between the light emitting units to cover the sidewalls of the light emitting units 2.
Specifically, the passivation layer 3 is located on the surface of each light emitting unit on the side facing away from the driving substrate 1 and on the side wall of each light emitting unit. After the epitaxial layer is etched to form the light-emitting unit, the side wall can generate defects, so that the formation of the passivation layer 3 on the surface of the light-emitting unit 2 can reduce the defects of the side wall, reduce non-radiative recombination and increase the light-emitting efficiency.
For the red light emitting cell in the structure of fig. 2, and the red and green light emitting cells in the structure of fig. 3, the passivation layer 3 may also protect the quantum dots from the subsequent process and the sidewalls of the light emitting cells.
In particular, the passivation layer 3 may be made of SiO 2 、AlN、Al 2 O 3 One or more materials in AlON are manufactured by atomic layer deposition or plasma chemical vapor deposition. The passivation layer 3 surrounds the light emitting side surface and the side wall of the light emitting unit, the portion of the passivation layer 3 covering the light emitting side surface of the light emitting unit is a plane, and the portion covering the side wall of the light emitting unit is an inclined plane. The passivation layer of the inclined surface portion has a size corresponding to the thickness of the light emitting unit of about 4 μm to 20 μm, and the passivation layer 3 has a thickness of about 1nm to 1 μm. The inclined surface is favorable for forming the passivation layer on the side wall of the light-emitting unit, and the included angle between the plane part of the passivation layer and the inclined surface part is about 95-160 degrees.
As shown in fig. 2 and 3, the display device is further provided with a second filter layer 4 on the surface of some of the light emitting units. Specifically, when the structure shown in fig. 2 is adopted, the second filter layer 4 is located on the passivation layer 3 on the surface and the sidewall of the red light emitting unit 2r facing away from the side of the driving substrate. When the structure shown in fig. 3 is adopted, the second filter layer 4 is located on the passivation layer 3 on the surface and the side wall of each red light emitting unit 2r and each green light emitting unit 2g facing away from the side of the driving substrate.
The passivation layer 3 on the surface of the light emitting unit 2 has the same shape as the light emitting unit 2, and thus the second filter layer 4 formed on the surface of the passivation layer 3 has a flat portion and a slope portion as the passivation layer 3. Wherein the planar portion of the second filter layer 4 corresponds to the light-emitting side surface of the light-emitting unit, and the inclined surface portion corresponds to the side wall of the light-emitting unit. The inclined surface of the passivation layer 3 facilitates the formation of the second filter layer 4 thereon, and the planar portion of the second filter layer 4 has an angle of about 95 deg. to about 160 deg. with the inclined surface portion.
In the embodiment of the present invention, the second filter layer 4 is used for transmitting red light and green light and reflecting blue light. Since the conversion efficiency of the color conversion material for the blue light emitted from the light emitting chip is not 100%, the direct emission of the unused blue light may cause a problem of color shift between the red light emitting unit and the green light emitting unit. Therefore, the second filter layer 4 is arranged on the light emitting side of the red light emitting unit and the green light emitting unit, so that the unused blue light can be reflected back to the light emitting unit to excite the color conversion material again, and the light emitting efficiency of the red light emitting unit and the green light emitting unit is improved.
According to the embodiment of the invention, the first filter layer 23 and the second filter layer 4 are arranged to form the reflecting cavities for the light rays with different colors, so that the conversion efficiency of blue light can be improved, and the light loss can be reduced.
Fig. 4 shows an optical path of a red light emitting unit or a green light emitting unit, wherein a dotted line represents an optical path of blue light, and a solid line represents an optical path of red light or green light stimulated-emitted by a color conversion layer in the red light emitting unit or the green light emitting unit.
As shown in fig. 4, blue light emitted from the light-emitting layer 212 in the light-emitting chip 21 is emitted in each direction, and a part of the blue light is incident on the nanopore h, and is converted into red light or green light after exciting the color conversion material. The converted red light or green light is emitted in various directions, wherein a part of the red light or green light is emitted outwards through the second filter layer 4, and the other part of the red light or green light emitted to the side of the light emitting chip 21 is reflected by the first filter layer 23 and then outwards emitted. The blue light which is not completely converted cannot pass through the second filter layer 4, is reflected back to the light-emitting unit by the second filter layer 4, passes through the first filter layer 23 and the epitaxial layer of the light-emitting chip, is reflected by the electrode, and excites the color conversion material again to be converted into red light or green light to be emitted outwards until the blue light is completely converted. And blue light emitted from the side surface of the light emitting chip 21 is reflected by the second filter layer 4 at the side wall and then returns to the light emitting unit, and is converted into red light or green light by the excitation color conversion material and then emitted outwards. Therefore, only the converted red light or green light can be emitted outwards from the light-emitting unit, the conversion efficiency of the blue light is improved, the emission efficiency of the red light or green light is improved, and the light loss is reduced.
Fig. 5 shows the optical path of the blue light emitting unit, wherein the dashed line represents the optical path of blue light.
As shown in fig. 5, the blue light emitting unit is disposed adjacent to the red light emitting unit and the green light emitting unit, and thus the sidewall of the blue light emitting unit is adjacent to the second filter layer 4 at the periphery of the red light emitting unit or the green light emitting unit. The nano holes in the blue light-emitting unit are not filled or filled with transparent medium, the blue light emitted by the light-emitting chip 21 is emitted in all directions, the blue light emitted from the front surface is directly emitted outwards, the blue light emitted from the side surface is reflected by the second filter layer 4 at the side wall and then changes direction, and finally is emitted from the front surface of the blue light-emitting unit after multiple reflections, so that the light-emitting efficiency of the front surface of the blue light-emitting unit can be enhanced, and crosstalk is reduced.
The second filter layer 4 positioned in the isolation groove U also serves as an isolation layer, on one hand, the effect of reflecting blue light by the second filter layer 4 can prevent the blue light from emitting to adjacent light-emitting units to generate crosstalk, and on the other hand, the loss of the blue light can be reduced, and the light emitting efficiency is improved. The isolation properties of the second filter layer 4 achieved by reflection also avoid the problem of reduced device performance due to light absorption and heating.
In practice, the first filter layer 23 and the second filter layer 4 may each be a bragg reflective layer. The bragg reflection layer is generally a periodic film formed by alternately arranging at least two materials with high refractive index and materials with low refractive index, and the refractive index and thickness of the materials of the film layer can be adjusted to enable the reflectivity of the first optical filter layer 23 and the second optical filter layer 4 to reach more than 95%, even close to 100%.
For the first filter layer 23, the first filter layer 23 can have lower reflectivity in a blue light wave band (420 nm-480 nm) and higher reflectivity in a green light wave band (500 nm-580 nm) and a red light wave band (600 nm-700 nm) through design, so that the effects of transmitting blue light and reflecting red light and green light are realized.
For the second filter layer 4, the reflectivity of the second filter layer 4 in the blue light wave band (420 nm-480 nm) is higher, and the reflectivity of the second filter layer in the green light wave band (500 nm-580 nm) and the reflectivity in the red light wave band (600 nm-700 nm) are lower, so that the effects of reflecting blue light and transmitting red light and green light are realized.
In the concrete implementation, siO can be adopted 2 And TiO 2 The Bragg reflection layer is formed by repeatedly superposing two materials with different refractive indexes. The bragg reflection layer may be a single stack structure, a multi-stack structure, or a graded structure, which is not limited herein. In addition to this In addition, the material of the Bragg reflection layer may be one or a combination of materials including, but not limited to, silicon oxide, titanium oxide, hafnium oxide, magnesium fluoride, yttrium oxide, zinc sulfide, zirconium oxide, and silicon nitride.
In the embodiment of the present invention, the first filter layer 23 has a planar structure, and the thickness is about 200nm to 1000nm. The second filter layer 4 comprises a planar portion and a beveled portion, the planar portion and beveled portion having a thickness comparable to about 200nm to about 3 μm. The angle between the plane part and the inclined plane part is about 95-160 degrees.
As shown in fig. 2 and 3, the display device further includes: a bonding layer 5 and a package substrate 6. The bonding layer 5 is located on the surface of the second filter layer 4 facing away from the side of the drive substrate 1. The encapsulation substrate 6 is located on the surface of the bonding layer 5 facing away from the side of the drive substrate 1.
The bonding layer 5 transmits red, green and blue light, and is used for bonding or attaching the light emitting unit to the package substrate 6. The bonding layer 5 can be made of silicon dioxide, aluminum oxide, epoxy resin, epoxy plastic package material, silica gel or organic silicon plastic, and the thickness is about 100 nm-1000 nm.
The package substrate 6 is transparent to red, green and blue light, and may be partially transparent or fully transparent. The package substrate 6 is located at the outermost side of the device and serves to protect and support the functional area of the device. The package substrate 6 may have one or more qualities such as, but not limited to, scratch-resistant, shatter-resistant, heat-resistant, flexible, electrically conductive and/or electrically resistant, providing polarized light filtration and/or coloring. The package substrate 6 may be made of sapphire, quartz glass, or the like, and is not limited thereto.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (10)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210417950.9A CN116978894A (en) | 2022-04-20 | 2022-04-20 | a display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210417950.9A CN116978894A (en) | 2022-04-20 | 2022-04-20 | a display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116978894A true CN116978894A (en) | 2023-10-31 |
Family
ID=88480093
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210417950.9A Pending CN116978894A (en) | 2022-04-20 | 2022-04-20 | a display device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116978894A (en) |
-
2022
- 2022-04-20 CN CN202210417950.9A patent/CN116978894A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11764336B2 (en) | Semiconductor light emitting device | |
| US20250275341A1 (en) | Micro led micro-display chip and manufacturing method thereof | |
| KR102131599B1 (en) | Light emitting diode and manufacturing method thereof | |
| JP2022003413A (en) | Display device | |
| CN116072800B (en) | Micro-LED display chip and preparation method thereof | |
| CN217280834U (en) | Display device | |
| JP7775299B2 (en) | Highly efficient light emitting device, unit pixel having the same, and display device having the same | |
| US20230378406A1 (en) | Light emitting device and led display apparatus having the same | |
| CN217426779U (en) | Display device | |
| US20230105156A1 (en) | Display panel, display apparatus, and preparation method for display panel | |
| CN101933171B (en) | Optical-electronic component and method for production thereof | |
| CN112151650A (en) | Micro light-emitting diode array and preparation method thereof | |
| CN118676287B (en) | Micro-LED display chip, display device and manufacturing method | |
| CN108196396A (en) | Backlight module and liquid crystal display device | |
| CN114823762A (en) | Light emitting diode chip, display device and preparation method | |
| CN116978894A (en) | a display device | |
| CN117691010A (en) | A kind of preparation method of full-color Micro-LED module and full-color module | |
| CN119302060A (en) | A display device | |
| CN117374097A (en) | Micro display unit and display device | |
| CN213366615U (en) | Micro LED Array | |
| US11411145B2 (en) | Light-emitting element package | |
| CN119008816B (en) | Micro display device and preparation method thereof | |
| US20250040324A1 (en) | Light emitting device and display device | |
| CN108008574A (en) | Backlight module and liquid crystal display device | |
| CN119767901A (en) | Display panel and display terminal |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |