TWI898390B - Display device - Google Patents

Abstract

A display device includes a driving substrate, a plurality of light-emitting elements, a first dielectric layer and a second dielectric layer. The light-emitting elements are disposed on the driving substrate. Each light-emitting element has a light-emitting surface facing away from the driving substrate, and sidewalls surrounding the light-emitting surface. The first dielectric layer surrounds and contacts the sidewall of a first light-emitting element among the light-emitting elements. The second dielectric layer surrounds and contacts the first dielectric layer. A first interface formed between the first dielectric layer and the second dielectric layer has an included angle with the sidewall of the first light-emitting element, and satisfies the following conditions: nL1＞n1＞n2＞1, wherein nL1 is the refractive index of the first light-emitting element, n1 is the refractive index of the first dielectric layer, and n2 is the refractive index of the second dielectric layer.

Description

Display device

The present invention relates to an electronic device, and in particular to a display device.

A micro-LED panel consists of an active device substrate and micro-LEDs (Micro LEDs) on the active device substrate, which are electrically connected to the driver circuit layer within the active device substrate. Micro-LED panels have become a focus of research and development for major manufacturers due to their advantages such as high brightness, high resolution, and high contrast.

However, due to the small size of microLEDs and the high proportion of light emitted from their sides, they can easily cause noticeable color shift when viewing displays at wide viewing angles. Related technologies include adjusting the thickness or shape of microLEDs of different colors to improve color shift, or adjusting the material of the light-emitting layer of each microLED to address this issue. However, these methods also increase the complexity of the microLED manufacturing process, making it difficult to reduce the cost of displays using microLEDs.

This invention provides a display device that effectively reduces the side light emission ratio of LEDs, improves color shift, and is easy to manufacture. When used in micro-LED display devices, it can effectively reduce production costs.

A display device according to one embodiment of the present invention includes a driver substrate, a plurality of light-emitting elements, a first dielectric layer, and a second dielectric layer. The light-emitting elements are disposed on the driver substrate. Each light-emitting element has a light-emitting surface facing away from the driver substrate and sidewalls surrounding the light-emitting surface. The first dielectric layer surrounds and contacts the sidewalls of a first light-emitting element among the light-emitting elements. The second dielectric layer surrounds and contacts the first dielectric layer. The first interface formed between the first dielectric layer and the second dielectric layer forms an angle with the sidewall of the first light-emitting element, and satisfies the following condition: nL1>n1>n2>1, where nL1 is the refractive index of the first light-emitting element, n1 is the refractive index of the first dielectric layer, and n2 is the refractive index of the second dielectric layer.

Based on the above, the display device of the embodiment of the present invention utilizes the angle between the interface formed by the first and second dielectric layers and the sidewalls of the light-emitting element, as well as the relationship between the refractive indices of the light-emitting element, the first and second dielectric layers, to effectively reduce the proportion of light intensity emitted from the sidewalls of the light-emitting element to the total light intensity of the light-emitting element. This improves the forward light output of the light-emitting element and alleviates the color shift of the display light beam in the display device. Furthermore, compared to methods that use light-emitting elements of different sizes or materials to improve side light leakage, the light-emitting elements of this embodiment can be of uniform size or thickness, facilitating their manufacture and transfer. This can effectively reduce production costs when used in micro-LED display devices.

To make the above features and advantages of the present invention more clearly understood, the following examples are given and described in detail with reference to the accompanying drawings.

10,10A: Display device

100: Drive substrate

110A, 110B, 110C: Light-emitting element

110AS, 110BS, 110CS: Sidewalls

100T, 110T: Top

111: First type semiconductor layer

112: Type II semiconductor layer

113: Luminescent layer

120,130: Dielectric layer

G: Gap

IF1, IF2, IF3: Interface

L1: Forward light

L2: Side light

N1, N2: normal line

X, Y, Z: Direction

αA, αB, αC: Angle

θ1, θ2, θ3: Angles

I-I: section line

Figure 1A is a schematic top view of a display device according to one embodiment of the present invention.

Figure 1B is a schematic cross-sectional view of Figure 1A along line I-I.

Figure 2 is a schematic top view of a display device according to another embodiment of the present invention.

Figures 3A and 3B are schematic diagrams of the optical principle of improving side light emission according to an embodiment of the present invention.

As used herein, "about," "approximately," "substantially," or "substantially" includes the stated value and the average within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, taking into account the measurement in question and the specific amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within, for example, ±30%, ±20%, ±15%, ±10%, or ±5%. Furthermore, as used herein, "about," "approximately," "substantially," or "substantially" can be selected based on process characteristics, measurement properties, cutting properties, or other properties, rather than using a single standard deviation to apply to all properties. That is, a right angle or any angle depicted herein can be substantially rounded with a small radius of curvature.

In the accompanying drawings, the thickness of layers, films, panels, regions, etc., is exaggerated for clarity. It should be understood that when an element, such as a layer, film, region, or substrate, is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. As used herein, "connected" can refer to physical and/or electrical connections. Furthermore, "electrically connected" can mean the presence of other elements between two elements.

Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

Figure 1A is a schematic top view of a display device according to an embodiment of the present invention. Referring to Figure 1A , display device 10 includes a driver substrate 100 and a plurality of light-emitting elements (e.g., light-emitting element 110A, light-emitting element 110B, and light-emitting element 110C) arranged in an array in directions X and Y on driver substrate 100. A plurality of dielectric layers 120 are disposed on driver substrate 100, surrounding and contacting light-emitting elements 110A, 110B, and 110C, respectively. A dielectric layer 130 is disposed on driver substrate 100, surrounding and contacting each of dielectric layers 120. The light-emitting elements 110A, 110B, and 110C can be defined as display sub-pixels of the display device 10, which receive electrical signals from the driving substrate 100 and emit light beams to form display light.

The driver substrate 100 includes various signal lines (e.g., data lines, scan lines, or power lines). For example, it may be made of a silicon wafer and include a complementary metal oxide semiconductor (CMOS) substrate. This improves the response speed of the switching elements in the driver substrate 100 and reduces power consumption, thereby meeting the fast response and high-resolution requirements of the display device 10. However, the present invention is not limited to this. In other embodiments, the driver substrate 100 may also be a printed circuit board (PCB). In other embodiments, the driver substrate 100 may also be a combination of a glass substrate and a pixel circuit layer, wherein the pixel circuit layer is formed on the glass substrate using a semiconductor process and may include active components (such as thin film transistors) and various signal lines (such as data lines, scan lines, or power lines), but is not limited thereto.

On the other hand, the plurality of light-emitting elements (e.g., light-emitting elements 110A, 110B, or 110C) may be, for example, micro light-emitting diodes (micro LEDs), sub-millimeter light-emitting diodes (mini LEDs), or light-emitting diodes of other sizes, but the present invention is not limited thereto. For example, the present embodiment uses micro LEDs, and the display device 10 may be a micro LED display device. The light-emitting element may be an ultraviolet (UV) light-emitting diode or a blue light-emitting diode. On the other hand, the light-emitting element of the present embodiment may be a flip-chip type light-emitting diode or a vertical-chip type light-emitting diode. For example, in this embodiment, electrodes (not shown) located on the same side of each light-emitting device epitaxial structure or electrodes (not shown) on opposite sides are aligned with corresponding bonding pads (not shown) on the driver substrate 100 and bonded together using conventional surface-mount technology (SMT) to achieve electrical connection between the light-emitting devices 110A, 110B, and 110C and the driver substrate 100. However, the present invention is not limited to this.

FIG1B is a schematic cross-sectional view taken along line I-I of FIG1A . Referring to both FIG1A and FIG1B , each of light-emitting elements 110A, 110B, and 110C may have a top surface 110T and be disposed opposite the top surface 100T of the driver substrate 100. The description of light-emitting elements 110B and 110C can be similarly applied to the description of light-emitting element 110A. Each light-emitting element has a light-emitting surface facing away from the driver substrate 100 and sidewalls surrounding the light-emitting surface. Top surface 110T may be considered the light-emitting surface of light-emitting elements 110A, 110B, and 110C, and the light beam emitted from top surface 110T by each light-emitting element may be referred to as forward light L1. On the other hand, each of the light-emitting elements 110A, 110B, and 110C also has sidewalls 110AS, 110BS, and 110CS connected to the top surface 110T. The light beams emitted from the sidewalls 110AS, 110BS, and 110CS can be referred to as sidelight L2. It's worth noting that the propagation directions of the forward light L1 and sidelight L2 aren't completely linear but can have a range of light output. Therefore, the propagation directions of the forward light L1 and sidelight L2 can refer to the propagation directions of the light beams with the highest energy among the light beams emitted in various directions by the light-emitting element 110A, 110B, or 110C.

The materials of light-emitting elements 110A, 110B, and 110C may each include a first-type semiconductor layer 111, a light-emitting layer 113, and a second-type semiconductor layer 112 stacked sequentially from top to bottom in direction Z. The first-type semiconductor layer 111 may be an N-type semiconductor layer, and the second-type semiconductor layer 112 may be a P-type semiconductor layer, but the present invention is not limited to this. Furthermore, the first-type semiconductor layer 111 and the second-type semiconductor layer 112 may each include a multilayer structure comprising a highly doped layer with varying dopant concentrations and a semiconductor layer with a normal dopant concentration. For example, the portion of the second semiconductor layer 112 that contacts the bonding pad of the driver substrate 100 may include highly doped P ⁺ gallium nitride (GaN) to facilitate ohmic contact between the second semiconductor layer 112 and the bonding pad. In other embodiments, other materials may be used as the substrates for the first semiconductor layer 111 and the second semiconductor layer 112, such as gallium arsenide (GaAs), aluminum phosphide (AlP), gallium nitride (GaN), indium gallium nitride (InGaN), indium gallium phosphide (InGaP), aluminum gallium indium phosphide (AlGaInP), aluminum gallium phosphide (AlInP), gallium indium arsenide (InGaN), aluminum gallium nitride (AlGaN), etc. This embodiment is not limited to this.

The structure of the light-emitting layer 113 can be a multiple-quantum well (MQW) structure, a single quantum well structure, a double heterostructure, a single heterostructure, or a combination thereof. The present invention is not limited thereto. As shown in FIG1B , the light-emitting layer 113 is located between the first-type semiconductor layer 111 and the second-type semiconductor layer 112 . Therefore, the first-type semiconductor layer 111 can be used to provide electrons, and the second-type semiconductor layer 112 can be used to provide holes. The electrons and holes combine in the light-emitting layer 113, converting their energy into photons and emitting light.

In some embodiments, light-emitting element 110A may be a red LED for emitting red light, light-emitting element 110B may be a green LED for emitting green light, and light-emitting element 110C may be a blue LED for emitting blue light. Therefore, the wavelength of light emitted by light-emitting element 110A may be greater than the wavelengths of light emitted by light-emitting elements 110B and 110C. However, the present invention is not limited to this. In other embodiments, light-emitting elements 110A, 110B, or 110C may all be blue LEDs, and a wavelength conversion layer (not shown) may be disposed on the side of the dielectric layer 130 facing away from the driver substrate 100 to convert blue light into light of a different color. The present invention is not limited to this.

Meanwhile, multiple dielectric layers 120 surround and contact sidewalls 110AS, 110BS, and 110CS, respectively. Dielectric layer 130 contacts multiple dielectric layers 120. Interfaces IF1, IF2, and IF3 corresponding to light-emitting elements 110A, 110B, and 110C are formed between dielectric layer 130 and multiple dielectric layers 120. Depending on the actual design, no other layers may be present between dielectric layer 130 and dielectric layer 120. Alternatively, other layers may be present between dielectric layer 130 and dielectric layer 120. In some embodiments, the plurality of dielectric layers 120 and the dielectric layer 130 may directly contact the top surface 100T of the driving substrate 100. However, the present invention is not limited to this. In other embodiments, a light-absorbing layer or a black matrix layer may be disposed between the plurality of dielectric layers 120 and the driving substrate 100, or between the dielectric layer 130 and the driving substrate 100, to increase the contrast and resolution of the display device 10. The present invention is not limited to this.

It is worth noting that an angle αA may be formed between interface IF1 and sidewall 110AS, an angle αB may be formed between interface IF2 and sidewall 110BS, and an angle αC may be formed between interface IF3 and sidewall 110CS. In other words, in the cross-sectional view of display device 10, taking light-emitting element 110A as an example, dielectric layer 120 may have a triangular outline, wherein the base of the triangle is disposed on driver substrate 100 and the sidewall 110AS of triangular high-contact light-emitting element 110A is formed. Angle αA may be the angle of the triangular outline that protrudes away from driver substrate 100. Alternatively, it can be understood that on the top surface 100T of the driver substrate 100, island structures can be formed between each of the multiple light-emitting elements and the dielectric layer 120 that contacts each other. Interface IF1 surrounds light-emitting element 110A, interface IF2 surrounds light-emitting element 110B, and interface IF3 surrounds light-emitting element 110C. Interfaces IF1, IF2, and IF3 form the edges of each island structure, and the multiple island structures are separated from each other by the dielectric layer 130.

Furthermore, the refractive index nL of each light-emitting element, the refractive index n1 of the dielectric layer 120, and the refractive index n2 of the dielectric layer 130 can further satisfy the following condition: nL>n1>n2>1. For example, the refractive index of light-emitting element 110A is nL1, and the island structure of light-emitting element 110A satisfies the following condition: nL1>n1>n2>1. The dielectric layers 120 and 130 can be based on a light-transmitting polymer, such as optically clear adhesive (OCA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), etc., and can be fabricated from high-refractive-index nanoparticles doped with inorganic compounds, such as _silicon oxide ( _SiOx ), aluminum oxynitride ( _AlOxNy ), silicon nitride ( _SiNx ), niobium pentoxide ( _{Nb2O5 )} , titanium dioxide ( _TiO2 ), etc., thereby selecting appropriate refractive indices for the dielectric layers 120 and 130. In some embodiments, the dielectric layers 120 and 130 can also be composed of inorganic compounds, but the present invention is not limited thereto.

Taking light-emitting element 110A as an example, due to the aforementioned differences in refractive index between the various elements and the size of the angle αA, the sidelight L2 emitted from sidewall 110AS undergoes a first refraction at sidewall 110AS and a second refraction at interface IF1. These two refractions allow the sidelight L2, which would otherwise easily cause color shift by mixing different colors, to be directed in a direction similar to the forward light L1 of the display device 10 (e.g., in direction Z). This effectively reduces sidelight leakage from light-emitting element 110A. In other words, the proportion of the forward light intensity in light-emitting element 110A to the total light intensity is increased, thereby enhancing the brightness of the display screen of display device 10.

On the other hand, compared to related technologies, which minimize the difference in color peak values of different light-emitting elements (e.g., three-primary-color LEDs) at different viewing angles by adjusting the thickness of each layer of the light-emitting element, thereby reducing color shift issues at wide viewing angles, the light-emitting elements 110A, 110B, and 110C in this embodiment of the present invention can all be of substantially the same size or thickness. This reduces the difficulty in manufacturing and transferring each light-emitting element, and also helps improve the manufacturing yield of the display device 10 and reduce production costs.

In some embodiments, the refractive index nL of light-emitting elements 110A, 110B, and 110C may satisfy the following condition: 4 ≥ nL > 1. For example, the refractive index of light-emitting element 110A is nL1, and light-emitting element 110A satisfies the following condition: 4 ≥ nL1 > 1. In some embodiments, the refractive index n1 of dielectric layer 120 and the refractive index n2 of dielectric layer 130 may further satisfy the following conditions: 4 > n1 > 1, and 4 > n2 > 1. In some embodiments, the angles αA, αB, and αC may be less than or equal to 45 degrees and greater than 0 degrees. Under the above conditions, the lateral light leakage problem of the light-emitting elements 110A, 110B, and 110C can be further improved, thereby increasing the proportion of light emitted in the forward direction (e.g., toward direction Z) by each light-emitting element.

In some embodiments, light-emitting elements 110A, 110B, and 110C are designed to emit different colors of light, so the materials of each light-emitting element may differ slightly. Therefore, the following conditions can be satisfied: 4 ≧ nL1 > 1, 3.5 ≧ nL2 > 1, and 3.5 ≧ nL3 > 1, where nL1 is the refractive index of light-emitting element 110A, nL2 is the refractive index of light-emitting element 110B, and nL3 is the refractive index of light-emitting element 110C. For light-emitting elements with different refractive indices, the angles αA, αB, and αC can also be different. For example, assuming that the refractive layer 120 contacting the red-emitting light-emitting element 110A has an angle αA, the refractive layer 120 contacting the green-emitting light-emitting element 110B has an angle αB, and the refractive layer 120 contacting the blue-emitting light-emitting element 110C has an angle αC, then the angle αA can be greater than both the angles αB and αC. This optimizes the forward light output ratio of the light-emitting elements of different colors. The present invention is not limited to this.

It is worth noting that, to further effectively guide the sidelight L2 toward the normal viewing angle of the display device 10 (e.g., direction Z), the dielectric layer 130 can further extend into the gaps G between the multiple light-emitting elements (e.g., the gap G between the light-emitting element 110A and the light-emitting element 110B). Furthermore, the dielectric layer 130 can contact the top surface 100T of the driving substrate 100, thereby reducing the leakage rate of the sidelight L2 in directions X and Y. Furthermore, the dielectric layer 130 can encapsulate the light-emitting elements and the dielectric layer 120, thereby increasing the reliability and structural strength of the display device 10. However, the present invention is not limited to this.

The following examples illustrate the present invention in detail. Identical components are denoted by identical symbols, and descriptions of identical technical contents are omitted. For omitted parts, please refer to the aforementioned examples and will not be further elaborated below.

Figure 2 is a schematic top view of a display device according to another embodiment of the present invention. Display device 10A of this embodiment is similar to display device 10, differing in the principle of directing side light L2 toward a normal viewing angle. Specifically, the angles (e.g., angles αA, αB, and αB) of the refractive layer 120 of display device 10A protrude toward the driver substrate 100. To put it another way, taking light-emitting element 110A as an example, dielectric layer 120 can have an inverted triangular profile, with the base of the triangle facing away from the driver substrate 100 and the sidewalls 110AS of the triangular high-contact light-emitting element 110A facing away. Angle αA can be the portion of the triangular profile that protrudes toward the driver substrate 100.

With this configuration, the sidelight L2 emitted from the sidewall 110AS undergoes a single refraction on the sidewall 110AS, which facilitates total internal reflection at the interface IF1. This single refraction and total internal reflection facilitates the direction of the sidelight L2, which is similar to the forward light L1 of the display device 10. This effectively reduces sidelight leakage from the light-emitting element 110A, improving the image quality of the display device 10A at normal viewing angles. Alternatively, the ratio of the forward light intensity of the light-emitting element 110A to the total light intensity is increased, thereby enhancing the brightness of the display screen of the display device 10A.

Figures 3A and 3B are schematic diagrams of the optical principle of improving side light emission according to an embodiment of the present invention. The following further explains the parameter design principle of the display device 10 and the display device 10A according to the embodiment of the present invention. Please refer to Figure 3A first. Taking the light-emitting element 110A of the display device 10 as an example, after the side light L2 is emitted from the light-emitting layer 113, the light type distribution of the light-emitting element 110A at the side wall 110AS or the relationship between the light intensity and the angle can be obtained through optical simulation software or experiments. In this way, the angle between the side light L2 and the normal N1 of the side wall 110AS (i.e., the angle of incidence θ1) and the refraction angle θ2 after refraction can be obtained. The above values can be determined from Snell's Law to satisfy the following condition: nL*Sin(θ1)=n1*Sin(θ2). Furthermore, after the sidelight L2 strikes the interface IF1, the angle between the sidelight L2 and the normal N2 of the interface IF1 (i.e., the angle of incidence (θ2-αA)) and the angle of refraction (θ3) after refraction are determined. The above values can also be determined from Snell's Law to satisfy the following condition: n1*Sin(θ2-αA)=n2*Sin(θ3). Finally, the light exits the dielectric layer 130 in the direction Z. The dielectric layer 130 can be air or another optical film (not shown), further satisfying Snell's Law regarding refraction from the dielectric layer 130 to air or an optical film.

Under the aforementioned refractive conditions, simulation software can be used to input parameters such as the refractive index n1, n2, the refractive index nL of each light-emitting element, and the angles αA, αB, and αC. This allows for the optimized forward light L1 and side light L2 distribution of each light-emitting element to be constructed, resulting in a uniform light distribution across all viewing angles. This method completes the optical parameter architecture of the display device 10.

Please refer to FIG3B . Taking the light-emitting element 110A of the display device 10A as an example, it can be known from Snell's law that the following condition must be satisfied: nL*Sin(θ1)=n1*Sin(θ2); and after the side light L2 is irradiated on the interface IF1, it can be known that the angle between the side light L2 and the normal N2 of the interface IF1 (i.e., the angle of the incident angle (θ2+αA)) must satisfy the condition of total internal reflection. That is, the above value can be known from Snell's law to satisfy: n1*Sin(θ2+αA)>n2*Sin 90°, and finally exits the dielectric layer 130 in direction Z. The dielectric layer 130 may be surrounded by air or other optical layers (not shown), further satisfying Snell's law regarding refraction from the dielectric layer 130 to air or other optical layers. The method for verifying the optical parameter structure of the display device 10A can be found above and will not be elaborated here.

In summary, the display device of this embodiment of the present invention, through the angle between the interface formed by dielectric layers 120 and 130 and the sidewalls of the light-emitting element, and the matching of the refractive indices of the light-emitting element, dielectric layers 120, and dielectric layers 130, can effectively reduce the proportion of light intensity emitted from the sidewalls of the light-emitting element to the total light intensity of the light-emitting element, thereby improving the forward light output of the light-emitting element and improving the color shift of the display light beam in the display device. Furthermore, compared to methods that use light-emitting elements of different sizes or materials to improve side light leakage, the light-emitting elements of this embodiment can be of uniform size or thickness, making the light-emitting elements easier to manufacture and assemble, and effectively reducing production costs when used in micro-LED display devices.

Although the present invention has been disclosed above through embodiments, they are not intended to limit the present invention. Anyone with ordinary skill in the art may make minor modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the attached patent application.

10: Display device 100: Driver substrate 110A, 110B, 110C: Light-emitting element 110AS, 110BS, 110CS: Sidewalls 100T, 110T: Top surface 111: Type I semiconductor layer 112: Type II semiconductor layer 113: Light-emitting layer 120, 130: Dielectric layer G: Gap IF1, IF2, IF3: Interfaces L1: Forward light L2: Side light X, Y, Z: Directions αA, αB, αC: Angles

Claims (9)

A display device includes: a driving substrate; a plurality of light-emitting elements disposed on the driving substrate, wherein each of the light-emitting elements has a light-emitting surface facing away from the driving substrate and a sidewall surrounding the light-emitting surface, and the light-emitting elements include a first light-emitting element, a second light-emitting element, and a third light-emitting element; a first dielectric layer surrounding and contacting the sidewall of the first light-emitting element; and a second dielectric layer surrounding and contacting the first dielectric layer; a third dielectric layer, wherein the third dielectric layer surrounds and contacts the sidewall of the second light-emitting element, and the second dielectric layer surrounds and contacts the third dielectric layer; A fourth dielectric layer, wherein the fourth dielectric layer surrounds and contacts the sidewall of the third light-emitting element, the second dielectric layer surrounds and contacts the fourth dielectric layer, a first interface is formed between the first dielectric layer and the second dielectric layer, a second interface is formed between the third dielectric layer and the second dielectric layer, and a third interface is formed between the fourth dielectric layer and the second dielectric layer, a first angle between the first interface and the sidewall of the first light-emitting element is greater than a second angle between the sidewall of the second light-emitting element and the second interface, and the first angle is greater than a third angle between the sidewall of the third light-emitting element and the third interface, and The following condition is satisfied: nL1>n1>n2>1, where nL1 is the refractive index of the first light-emitting element, n1 is the refractive index of the first dielectric layer, and n2 is the refractive index of the second dielectric layer. The display device as described in claim 1, wherein the refractive index nL1 of the first light-emitting element satisfies the following condition: 4≧nL1＞1. The display device as described in claim 1, wherein the refractive index n1 of the first dielectric layer and the refractive index n2 of the second dielectric layer satisfy the following conditions: 4>n1>1, 4>n2>1. The display device as described in claim 1, wherein the second dielectric layer is further disposed in the gaps between the light-emitting elements and further contacts the driving substrate. The display device as described in claim 1, wherein the angle value of the first angle is less than or equal to 45 degrees and greater than 0 degree. The display device as described in claim 5, wherein in a cross-sectional direction of the first light-emitting element and the first dielectric layer, the first angle is toward the driving substrate. The display device as described in claim 5, wherein in a cross-sectional direction of the first light-emitting element and the first dielectric layer, the first angle is away from the driving substrate. The display device as described in claim 1, wherein the first light-emitting element, the second light-emitting element and the third light-emitting element are of different colors and satisfy the following conditions: 4≧nL1＞1, 3.5≧nL2＞1, 3.5≧nL3＞1, wherein nL2 is the refractive index of the second light-emitting element, and nL3 is the refractive index of the third light-emitting element. A display device as described in claim 8, wherein the wavelength of light emitted by the first light-emitting element is greater than the wavelength of light emitted by the second light-emitting element and the third light-emitting element.