Light-emitting device and preparation method and application thereof

Abstract

The invention relates to a light-emitting device and a preparation method and application thereof, the light-emitting device comprises a transparent conductive substrate, a hole transport layer, a light-emitting layer, a photoresist layer, an electron transport layer and an electrode layer, the photoresist layer is located between the light-emitting layer and the electron transport layer, the light-emitting layer is of a continuous layer structure, and the photoresist layer comprises pixel holes. According to the light-emitting device provided by the invention, the photoresist layer is arranged between the continuous light-emitting layer and the electron transport layer, and the pixel holes are formed in the photoresist layer, so that the region blocked by the photoresist and the region not blocked by the photoresist are formed on the surface of the light-emitting layer, the patterned isolation of the pixels of the light-emitting layer is realized, the integrity of the light-emitting layer is ensured, and the light-emitting efficiency is improved. And ultrahigh resolution can also be obtained, so that the light-emitting device can obtain bright, efficient and uniform light emission.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic information technology, and in particular to a light-emitting device and a preparation method and application thereof. Background Art

[0002] Light-emitting diodes (LEDs) are characterized by high resolution, high brightness, and fast response speed. They are emerging as the next generation display technology and play an important role in optical communications, augmented / virtual reality, and wearable devices. Metal halide perovskite light-emitting materials have the potential for high-resolution patterning and scalable manufacturing.

[0003] The traditional preparation method of micro-light-emitting devices generally adopts direct photolithography or etching operation on the light-emitting layer. For example, the prior art CN114420840A discloses a patterned halogen perovskite film and its preparation method and application, wherein a photoresist film is formed on the halogen perovskite film, and through exposure, development, etching and degumming in hydrohalic acid, the hydrohalic acid can coordinate with the metal ions in the halogen perovskite, and at the same time, the halogen perovskite is etched by its own acidity to obtain a patterned halogen perovskite. However, such direct photolithography or etching operation will cause defects and surface damage to the light-emitting layer, further destroying the luminescent performance of the micro-light-emitting device.

[0004] The quality of the light-emitting layer in the light-emitting device will affect the overall performance of the light-emitting device. The polycrystalline nature leads to unstable surface of the light-emitting layer, uneven emission and low electron transfer efficiency. Compared with polycrystalline, single crystal has an order of magnitude defect density suppression capability, and the carrier mobility is significantly improved, which is conducive to the preparation of high-efficiency light-emitting devices. Prior art CN216213544U discloses a pixelated perovskite thin film light-emitting device, in which a perovskite film that conducts the electron transport layer and the hole transport layer is formed by inkjet printing in the pixel pits distributed in the array. The light-emitting device realizes the array pixel arrangement of the perovskite film. The perovskite film is formed by inkjet printing technology to form a perovskite pattern that matches the pixel pit pattern, thereby forming a perovskite film with an array pixel arrangement. However, the surface stability and emission uniformity of the array-arranged perovskite film in the light-emitting device prepared by this process are insufficient, and the electron transfer efficiency of the light-emitting device needs to be improved.

[0005] Therefore, providing a lossless and high-performance light-emitting device has become an urgent problem to be solved. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a light-emitting device and a preparation method and application thereof. The light-emitting device provided by the present invention is provided with a photoresist layer between a continuous light-emitting layer and an electron transport layer. The photoresist layer containing pixel holes forms a photoresist-blocked area and a photoresist-unblocked area on the surface of the light-emitting layer, thereby realizing patterned isolation of the light-emitting layer pixels, and there is no need to etch the light-emitting layer, thereby avoiding defects and surface damage caused by etching, and ensuring the integrity of the light-emitting layer. At the same time, ultra-high resolution can also be obtained, so that the light-emitting device can obtain bright, efficient and uniform light emission.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a light-emitting device, comprising a transparent conductive substrate, a hole transport layer, a light-emitting layer, a photoresist layer, an electron transport layer and an electrode layer, wherein the photoresist layer is located between the light-emitting layer and the electron transport layer, the light-emitting layer is a continuous layer structure, and the photoresist layer comprises pixel holes.

[0009] In the present invention, the "pixel hole" refers to a hole structure in the photoresist layer that enables electrons to be transferred from the electron transport layer to the light-emitting layer and to recombine with holes to emit light, so that the hole structure in the photoresist layer does not block the light-emitting layer, and the area outside the hole structure blocks the light-emitting layer, thereby patterning and isolating the pixels of the light-emitting layer. For the specific structure, see Figure 1 or Figure 2 As shown in 41.

[0010] The light-emitting device provided by the present invention has a photoresist layer containing pixel holes arranged between a continuous light-emitting layer and an electron transport layer, and forms a photoresist-blocked area and a photoresist-unblocked area on the surface of the light-emitting layer. When current passes through the light-emitting device, a light-emitting layer area that is not blocked by the photoresist is formed in the area where the pixel holes exist in the photoresist layer, and electrons and holes are smoothly transmitted from the electrode layer and the transparent conductive substrate through the electron transport layer and the hole transport layer to the light-emitting layer for radiation recombination and luminescence; while a photoresist area blocked by the photoresist is formed in the area outside the pixel holes in the photoresist layer, and due to the presence of the photoresist, its insulating properties make it impossible to continue to transmit the electrons transmitted by the electron transport layer to the light-emitting layer, so that the recombination and luminescence of electrons and holes in the light-emitting layer cannot be achieved in the place where the photoresist exists, and the pixel holes of the photoresist layer are arranged to achieve patterned isolation between pixels of the light-emitting layer, and while ensuring the integrity and high quality of the light-emitting layer, the light-emitting device can achieve ultra-high resolution, so that the light-emitting device can obtain bright, efficient and uniform light emission.

[0011] Preferably, the light-emitting device is a micro light-emitting device.

[0012] Preferably, the light-emitting device comprises a transparent conductive substrate, a hole transport layer, a light-emitting layer, a photoresist layer, an electron transport layer and an electrode layer which are stacked in sequence.

[0013] Preferably, the transparent conductive substrate comprises ITO conductive glass.

[0014] Preferably, the composition of the hole transport layer includes PEDOT:PSS.

[0015] Preferably, the thickness of the hole transport layer is 30-50 nm, for example, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm.

[0016] Preferably, the composition of the light emitting layer includes single crystal material.

[0017] In the present invention, a single crystal material is used as the light-emitting layer. Compared with a polycrystalline material, it has an order of magnitude defect density suppression capability and significantly improves carrier mobility, which is beneficial to improving the performance of the light-emitting device.

[0018] Preferably, the composition of the light-emitting layer includes single crystal perovskite.

[0019] Preferably, the single crystal perovskite comprises CsPbX3 and / or MAPbY3, X and Y independently comprise any one of Cl, Br or I or a combination of at least two thereof, and MA is a methylamino organic cation.

[0020] Preferably, the thickness of the light-emitting layer is 100-400 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm or 400 nm.

[0021] Preferably, the photoresist layer comprises a negative photoresist.

[0022] Preferably, the negative photoresist comprises RFJ-220 negative photoresist.

[0023] Preferably, the thickness of the photoresist layer is 50-200 nm, for example, 50 nm, 80 nm, 110 nm, 140 nm, 170 nm or 200 nm.

[0024] In the present invention, if the thickness of the photoresist layer is too thin, the photoresist blocking will be insufficient, resulting in partial leakage; if the thickness of the photoresist layer is too thick, the photoresist edge will be seriously tailed, the interface will not be steep, and the light-emitting pixel crosstalk problem will occur.

[0025] Preferably, in the photoresist layer, the pixel holes are arranged in an array.

[0026] Preferably, the pixel hole is a through hole along the thickness direction of the photoresist layer.

[0027] In the present invention, a light emitting layer surface which is not blocked by the photoresist is formed in the pixel hole of the through hole structure.

[0028] The present invention adopts a through-hole pixel hole structure, which can avoid the existence of photoresist blocking the continued transmission of electrons transmitted by the electron transport layer to the light-emitting layer, thereby realizing the transmission of electrons to the light-emitting layer in the pixel hole area, and recombining with holes in the light-emitting layer to emit light.

[0029] Preferably, the hole structure of the pixel hole is a cubic structure.

[0030] Preferably, the cross-section of the single pixel hole has a shape including any one of a square, a rectangle, a diamond, a triangle or a circle, preferably a square.

[0031] Preferably, when the shape of the cross section of the single pixel hole is any one of a square, a rectangle, a rhombus or a triangle, the side length of the cross section of the single pixel hole is 2-100 μm, for example, 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc.

[0032] Preferably, when the cross-section of the single pixel hole is circular, the diameter of the cross-section of the single pixel hole is 2-100 μm, for example, 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm, etc.

[0033] In the present invention, the “cross-sectional shape” refers to the cross-sectional shape perpendicular to the thickness direction of the photoresist layer.

[0034] The present invention can achieve a pixel size of the light emitting device ranging from 2 μm to 100 μm by regulating the structure of the photoresist layer and the size of the pixel hole.

[0035] Preferably, in the horizontal direction, the spacing between adjacent single pixel holes is 2-50 μm, for example, 2 μm, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm or 50 μm.

[0036] In the present invention, the “horizontal direction” refers to a direction perpendicular to the thickness direction of each layer structure in the light-emitting device, and a direction perpendicular to the stacking direction of each layer structure in the light-emitting device.

[0037] Preferably, the light emitting device further comprises a passivation layer, a portion of the passivation layer is located on the surface of the light emitting layer in the pixel hole of the photoresist layer, and another portion of the passivation layer is located on a side surface of the photoresist layer away from the light emitting layer.

[0038] In the present invention, a passivation layer is provided in the light-emitting device, which can passivate the surface defects of the light-emitting layer, thereby reducing the surface defect density of the single crystal perovskite, improving the crystal quality, and enhancing the performance of the light-emitting device.

[0039] Preferably, the composition of the passivation layer includes any one of 2,4,6-triphenylphenazine oxide (TPPO) or tris(4-fluorophenyl)phosphine oxide (TFPPO).

[0040] Preferably, the thickness of the passivation layer is 0.5-2 nm, for example, 0.5 nm, 0.6 nm, 0.8 nm, 1.0 nm, 1.2 nm, 1.4 nm, 1.6 nm, 1.8 nm or 2.0 nm.

[0041] In the light-emitting device of the present invention, the thickness of the passivation layer at any position remains consistent.

[0042] Preferably, the composition of the electron transport layer includes any one of 4,6-bis(3,5-di(pyridin-3-yl)phenyl)-2-methylpyrimidine (B3PYMPM), 1,3,5-tri(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(4,4′-(N-(4-sec-butylphenyl)diphenylamine)] (TFB).

[0043] Preferably, the thickness of the electron transport layer is 20-40 nm, for example, 20 nm, 25 nm, 30 nm, 35 nm or 40 nm.

[0044] In the present invention, the thickness of the electron transport layer at any position remains consistent.

[0045] Preferably, the electron transport layer is located on a surface of the passivation layer away from the light-emitting layer.

[0046] Preferably, an electron injection layer is further included between the electron transport layer and the electrode layer.

[0047] Preferably, the electron injection layer comprises any one of LiF or MoO3.

[0048] Preferably, the thickness of the electron injection layer is 0.5-5 nm, for example, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm or 5 nm.

[0049] In the present invention, the thickness of the electron injection layer at any position remains consistent.

[0050] Preferably, the electrode layer is located on a surface of the electron injection layer that is away from the electron transport layer.

[0051] Preferably, the electrode layer is composed of any one of Al, Ag or Mn.

[0052] Preferably, the thickness of the electrode layer is 80-120 nm, for example, 80 nm, 90 nm, 100 nm, 110 nm or 120 nm.

[0053] In the present invention, the thickness of the electrode layer at any position remains consistent.

[0054] In a second aspect, the present invention provides a method for preparing a light-emitting device according to the first aspect, the method comprising the following steps:

[0055] A hole transport layer and a continuous light-emitting layer are sequentially prepared on a transparent conductive substrate; a photoresist layer containing pixel holes is prepared on the side of the light-emitting layer away from the hole transport layer by using a photolithography process, and then an electron transport layer and an electrode layer are sequentially formed on the substrate containing the photoresist layer to obtain the light-emitting device.

[0056] The preparation method provided by the present invention is an indirect photolithography method that utilizes photolithography technology to etch the photoresist layer on the light-emitting layer. The light-emitting layer in the light-emitting device does not need to be directly etched, so patterned isolation of the pixels of the light-emitting layer can be achieved, thereby avoiding structural defects and surface damage to the light-emitting layer caused by direct etching. The light-emitting device with controllable pixel size and ultra-high resolution prepared by the preparation method of the present invention can achieve bright, efficient and uniform light emission.

[0057] The present invention adopts a photolithography process to prepare a photoresist layer containing pixel holes on one side surface of a continuous light-emitting layer, and divides the light-emitting layer into a region blocked by the photoresist and an unblocked region (i.e., a region where the pixel holes exist). In the region blocked by the photoresist, due to the insulating property of the photoresist, electrons transmitted through the electron transport layer cannot be further transmitted to the light-emitting layer, so that the region where the light-emitting layer is blocked cannot realize the recombination of electrons and holes in the light-emitting layer to emit light. In the region unblocked by the photoresist where the pixel holes exist, due to the absence of insulating photoresist, electrons transmitted through the electron transport layer can be further transmitted to the light-emitting layer, and recombine with holes in the light-emitting layer to realize light emission. By introducing the photoresist layer and designing a specific structure, combined with an indirect photolithography method, patterned isolation of pixels of the light-emitting layer is realized, thereby improving the resolution of the light-emitting device, and preparing a light-emitting device with bright, efficient and uniform light emission.

[0058] Preferably, the preparation method further comprises washing the transparent conductive substrate.

[0059] Preferably, the washing agent used in the washing includes any one of glass detergent, deionized water, acetone or ethanol, or a combination of at least two of them.

[0060] In the present invention, there is no specific limitation on the washing method, including but not limited to ultrasound or immersion, and those skilled in the art can select it according to needs.

[0061] Preferably, the washing is followed by drying.

[0062] In the present invention, there is no specific limitation on the drying method after washing, including but not limited to nitrogen drying, natural air drying and vacuum drying, etc. Those skilled in the art can select according to needs.

[0063] Preferably, the hole transport layer is prepared by spin coating and then annealing.

[0064] Preferably, in the preparation of the hole transport layer, the spin coating rotation speed is 3500-4500 rpm, for example, 3500 rpm, 3600 rpm, 3700 rpm, 3800 rpm, 3900 rpm, 4000 rpm, 4100 rpm, 4200 rpm, 4300 rpm, 4400 rpm or 4500 rpm, etc.

[0065] Preferably, in the preparation of the hole transport layer, the spin coating time is 40-50 s, for example, 40 s, 42 s, 44 s, 46 s, 48 ​​s or 50 s.

[0066] Preferably, in the preparation of the hole transport layer, the annealing temperature is 100-200°C, for example, 100°C, 120°C, 140°C, 160°C, 180°C or 200°C.

[0067] Preferably, in the preparation of the hole transport layer, the annealing time is 10-30 min, for example, 10 min, 15 min, 20 min, 25 min or 30 min.

[0068] Preferably, the specific preparation process of the light-emitting layer includes: growing a single crystal epitaxial light-emitting layer on a substrate using a vapor phase epitaxy method, peeling off the single crystal epitaxial light-emitting layer on the substrate in a nitrogen-filled environment to obtain a self-supporting single crystal epitaxial light-emitting layer, and then transferring the self-supporting single crystal epitaxial light-emitting layer to the hole transport layer to obtain a continuous light-emitting layer.

[0069] The single crystal light-emitting layer prepared by the preparation method adopted in the present invention can realize bright, efficient and uniform light emission, and promote the preparation of micro-nano scale light-emitting devices with small pixel size and ultra-high resolution.

[0070] In the present invention, the preparation process of growing a single crystal epitaxial light-emitting layer on a substrate by the vapor phase epitaxy method adopts the process commonly used in the prior art, that is, the substrate is placed downstream of the quartz tube of a single-zone tubular furnace, the constituent material of the light-emitting layer is placed in the center of the heating furnace, the quartz tube is evacuated, and then, the quartz tube is inflated with N2 gas flow flowing from the upstream to the downstream, the temperature in the quartz tube is set at 550-650°C, and the pressure is set to 40-200Torr, and the single crystal epitaxial light-emitting layer is obtained on the substrate.

[0071] Preferably, the substrate comprises any one of graphene, sapphire, fluorophlogopite or natural muscovite mica, or a combination of at least two of them.

[0072] Preferably, the thickness of the epitaxial light-emitting layer is 100-400 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm or 400 nm.

[0073] Preferably, the photolithography process includes coating, baking, exposure, development and rinsing.

[0074] Preferably, in the photolithography process, the coating method includes spin coating of photoresist.

[0075] Preferably, the photoresist comprises a negative photoresist.

[0076] Preferably, the negative photoresist comprises RFJ-220 negative photoresist.

[0077] The present invention further prefers negative photoresist, and the subsequent operation and materials used in the operation process cause minimal damage to the light-emitting layer, avoiding damage to the structure of the light-emitting layer and surface defects, thereby ensuring the light-emitting layer is in an intact state. If the present invention uses positive photoresist, the developer of the positive photoresist is an alkaline solution and the rinse solution is water, which will cause structural damage to the light-emitting layer, which is not conducive to the preparation of the light-emitting device.

[0078] Preferably, in the photolithography process, the rotation speed of the spin coating is 2000-3000 rpm, for example, 2000 rpm, 2200 rpm, 2400 rpm, 2600 rpm, 2800 rpm or 3000 rpm.

[0079] Preferably, in the photolithography process, the spin coating time is 20-40 s, such as 20 s, 22 s, 24 s, 26 s, 28 s or 30 s.

[0080] Preferably, the baking temperature is 80-100°C, for example, 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, etc.

[0081] Preferably, the baking time is 80-100 s, such as 80 s, 85 s, 90 s, 95 s or 100 s.

[0082] Preferably, the specific process of the exposure includes: using a photolithography mask plate to cover the baked photoresist, and then irradiating the photoresist with the photolithography mask plate on the surface by a UV photolithography machine to form an exposed area and an unexposed area on the photoresist.

[0083] Preferably, the photolithography mask comprises a glass layer and a chrome layer disposed on a portion of the glass layer.

[0084] Preferably, the area on the glass layer where the chromium layer is provided is a light-proof area, and the area on the glass layer where the chromium layer is not provided is a light-transmitting area.

[0085] The present invention adopts an ultraviolet photolithography machine to irradiate the photoresist whose surface is covered with a photolithography mask plate, and a light-proof area with a chromium layer is provided on the glass layer of the photolithography mask plate, and an unexposed area is formed on the corresponding covered photoresist, and a light-transmitting area without a chromium layer is provided on the glass layer of the photolithography mask plate, and an exposed area is formed on the corresponding covered photoresist.

[0086] Preferably, the shape of the opaque area of ​​the photolithography mask is the same as the shape of the pixel hole in the photoresist layer.

[0087] Preferably, the exposure time is 3-6 s, for example, 3 s, 3.5 s, 4 s, 4.5 s, 5 s, 5.5 s or 6 s.

[0088] Preferably, the specific process of the development includes: using a developer to dissolve the unexposed area on the photoresist.

[0089] Preferably, the developer comprises any one of chlorobenzene, toluene, dichlorobenzene or m-xylene, or a combination of at least two of them.

[0090] Preferably, the solvent used for rinsing includes any one of isopropanol or acetone.

[0091] The rinsing solvent used in the present invention will not damage the light-emitting layer, thereby further ensuring the preparation of the light-emitting device without damaging the light-emitting layer.

[0092] Preferably, nitrogen gas is used to blow dry after rinsing.

[0093] Preferably, the preparation of the photoresist layer also includes the preparation of a passivation layer.

[0094] Preferably, the specific process for preparing the passivation layer includes: adding a passivation liquid dropwise onto the surface of the light-emitting layer in the pixel hole, and then spin coating to obtain the passivation layer.

[0095] In the preparation process of the passivation layer of the present invention, the passivation liquid is firstly added dropwise onto the surface of the light-emitting layer in the pixel hole that is not blocked by the photoresist, and then spin coating is performed to transfer part of the passivation liquid onto the photoresist layer, thereby obtaining a passivation layer in which a part is located on the surface of the light-emitting layer in the pixel hole of the photoresist layer and another part is located on the surface of the photoresist layer away from the light-emitting layer. Compared with directly spin coating the passivation liquid, the phenomenon that the passivation liquid cannot be spin coated onto the surface of the light-emitting layer in the pixel hole can be effectively avoided.

[0096] Preferably, during the preparation of the passivation layer, the spin coating rotation speed is 6000-7000 rpm, for example, 6000 rpm, 6200 rpm, 6400 rpm, 6600 rpm, 6800 rpm or 7000 rpm.

[0097] Preferably, during the preparation of the passivation layer, the spin coating time is 0.5-5 min, for example, 0.5 min, 1 min, 1.5 min, 2 min, 2.5 min, 3 min, 3.5 min, 4 min, 4.5 min or 5 min.

[0098] Preferably, the solute of the passivation solution includes any one of 2,4,6-triphenylphenazine oxide (TPPO) or tris(4-fluorophenyl)phosphine oxide (TFPPO).

[0099] Preferably, the solvent of the passivation solution includes any one of chlorobenzene, dichlorobenzene or m-xylene.

[0100] Preferably, the electron transport layer and the electrode layer are prepared by an evaporation process.

[0101] Preferably, the evaporation is performed in a vacuum environment.

[0102] Preferably, the evaporation pressure is 3×10 -4 -6×10 -4 Pa, for example 3×10 -4 Pa, 3.5×10 -4 Pa, 4×10 -4 Pa, 4.5×10 -4 Pa, 5×10 -4 Pa, 5.5×10 -4 Pa or 6×10 -4 Pa et al.

[0103] After preparing a photoresist layer containing pixel holes, the present invention prepares an electron transport layer by evaporation, wherein a portion of the electron transport layer is located on the passivation layer on the photoresist layer, and a portion of the electron transport layer is located on the passivation layer on the surface of the light-emitting layer exposed by the pixel holes, and the thickness of the electron transport layer at any position always remains consistent.

[0104] Preferably, an electron injection layer is further provided on a side of the electron transport layer close to the electrode layer.

[0105] Preferably, the electron injection layer is disposed on the electron transport layer by evaporation.

[0106] Preferably, the electrode layer is disposed on the electron injection layer by evaporation.

[0107] In the present invention, the electron injection layer and the electrode layer are sequentially formed on the electron transport layer by evaporation. In the light-emitting device, the thickness of the electron injection layer at any position is always consistent, and the thickness of the electrode layer at any position is also always consistent.

[0108] As a preferred technical solution of the present invention, the preparation method comprises the following steps:

[0109] (1) ultrasonically washing a transparent conductive substrate with a glass detergent, deionized water, acetone or ethanol, or a combination of at least two of the detergents, and drying the substrate to obtain a cleaned transparent conductive substrate; spin coating PEDOT:PSS on the cleaned transparent conductive substrate at a rotation speed of 3500-4500 rpm for 40-50 seconds, and then annealing at 100-200° C. for 10-30 minutes to obtain a hole transport layer;

[0110] (2) growing a single crystal epitaxial light-emitting layer on a substrate by vapor phase epitaxy under the conditions of N2 gas flow, temperature of 550-650°C and pressure of 40-200 Torr, peeling off the single crystal epitaxial light-emitting layer on the substrate in a nitrogen-filled environment to obtain a self-supporting single crystal epitaxial light-emitting layer with a thickness of 100-400 nm, and then transferring the self-supporting single crystal epitaxial light-emitting layer to the hole transport layer formed in step (1) to obtain a continuous light-emitting layer;

[0111] (3) Spin-coating a negative photoresist onto the side of the light-emitting layer away from the hole transport layer at a rotation speed of 2000-3000 rpm for 20-40 seconds, then baking at 80-100° C. for 80-100 seconds, and then covering the baked photoresist with a photomask, wherein the shape of the opaque area in the photomask is the same as the shape of the cross section of the pixel hole, and using an ultraviolet photolithography machine to expose the photoresist with the photomask on the surface for 3-6 seconds to form an exposed area and an unexposed area on the photoresist, and then using a developer to dissolve the unexposed area on the photoresist, and finally, rinsing the photoresist layer with a solvent, and drying with nitrogen to obtain a photoresist layer containing pixel holes, wherein the light-emitting layer in the pixel holes is not blocked by the photoresist;

[0112] (4) adding a passivation solution to the surface of the light-emitting layer in the pixel hole, and then performing spin coating at a speed of 6000-7000 rpm for 0.5-5 min to obtain a passivation layer, transferring the prepared substrate to a vacuum thermal evaporation chamber, and -4 -6×10 -4 Under a pressure of 1.3 Pa, a stacked electron transport layer, an electron injection layer and an electrode layer are sequentially prepared on the obtained passivation layer by evaporation to obtain the light-emitting device.

[0113] In a third aspect, the present invention provides an application of the light-emitting device as described in the first aspect, wherein the light-emitting device is applied in the fields of optical communication, wearable devices, virtual reality or augmented reality.

[0114] The light-emitting device provided by the present invention is suitable for any application field that can be thought of by those skilled in the art.

[0115] Compared with the prior art, the present invention has at least the following beneficial effects:

[0116] (1) The light-emitting device provided by the present invention has a photoresist layer disposed between a continuous light-emitting layer and an electron transport layer. The photoresist layer containing pixel holes forms a surface of the light-emitting layer with a region blocked by the photoresist and a region not blocked by the photoresist, thereby achieving patterned isolation of pixels of the light-emitting layer. While ensuring the integrity of the light-emitting layer, ultra-high resolution can be obtained, so that the light-emitting device can obtain bright, efficient and uniform light emission.

[0117] (2) The preparation method provided by the present invention is an indirect photolithography method that utilizes photolithography technology to etch the photoresist layer on the light-emitting layer. It does not need to directly etch the light-emitting layer in the light-emitting device, so as to achieve patterned isolation of the light-emitting layer pixels, thereby avoiding structural defects and surface damage to the light-emitting layer caused by direct etching. The light-emitting device with controllable pixel size and ultra-high resolution prepared by the preparation method of the present invention can achieve bright, efficient and uniform light emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0118] Figure 1 is a schematic diagram of the cross-sectional structure of the light-emitting device prepared by the present invention;

[0119] Figure 2 It is a schematic diagram of the three-dimensional structure of the light-emitting layer and the photoresist layer in the light-emitting device prepared by the present invention;

[0120] Among them, 1-transparent conductive substrate, 2-hole transport layer, 3-light-emitting layer, 4-photoresist layer, 41-pixel hole, 5-passivation layer, 6-electron transport layer, 7-electron injection layer, and 8-electrode layer.

[0121] Figure 3 It is a schematic top view of a part of the structure of the photolithography mask in the present invention;

[0122] Wherein, A is the side length of the opaque area of ​​the photolithography mask in the horizontal direction, and B is the horizontal spacing between adjacent opaque areas in the photolithography mask.

[0123] Figure 4 This is a partial electroluminescence picture of the single crystal CsPbBr3 micro LED light-emitting device of Example 1 of the present invention.

[0124] Figure 5 This is a partial electroluminescence picture of the single crystal CsPbBr3 micro LED light-emitting device of Example 2 of the present invention.

[0125] Figure 6 This is a partial electroluminescence picture of the single crystal CsPbBr3 micro LED light-emitting device of Example 3 of the present invention.

[0126] Figure 7 It is a schematic diagram of partial electroluminescence of the single crystal CsPbClBr2 micro-LED light-emitting device of Example 4 of the present invention.

[0127] Figure 8 This is the current density / brightness-voltage relationship curve of the single crystal CsPbBr3 micro LED light-emitting device in Example 1 of the present invention.

[0128] Fig. 9This is the relationship curve between EQE (external quantum efficiency) and brightness of the single crystal CsPbBr3 micro LED light-emitting device in Example 1 of the present invention.

[0129] Fig.10 This is a curve showing the relationship between the luminous intensity and wavelength of the single crystal CsPbBr3 micro LED light emitting device under different voltages in Example 1 of the present invention.

[0130] Fig.11 This is the current density / brightness-voltage relationship curve of the single crystal CsPbClBr2 micro LED light-emitting device of Example 4 of the present invention.

[0131] Fig.12 This is the relationship curve between EQE (external quantum efficiency) and brightness of the single crystal CsPbClBr2 micro LED light-emitting device of Example 4 of the present invention. DETAILED DESCRIPTION

[0132] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0133] The glass detergent used in the following examples is environmentally friendly cleaning agent Fisher 2000-5, manufactured by Luoyang Guluo Glass Co., Ltd. It is composed of surfactants, solvents and other auxiliary ingredients and is a light blue transparent liquid.

[0134] The ITO conductive glass used in the following examples has a thickness of 180 nm and a rectangular cross-section with a size of 6×20 mm.

[0135] The preparation process of growing a single crystal epitaxial light-emitting layer on a substrate by the vapor phase epitaxy method mentioned in the following embodiments adopts the process commonly used in the prior art, that is, placing the substrate downstream of the quartz tube of a single-zone tubular furnace, placing the component material of the light-emitting layer at the end in the center of the heating furnace, pumping air into the quartz tube, and then inflating the quartz tube with N2 gas flow flowing from upstream to downstream, setting the temperature in the quartz tube to 550-650°C and the pressure to 40-200Torr, to obtain the single crystal epitaxial light-emitting layer on the substrate.

[0136] The photolithography mask used in the following embodiments includes a glass layer and a chromium layer disposed on a portion of the glass layer, wherein the area on the glass layer where the chromium layer is disposed is a light-proof area, and forms an unexposed area during the subsequent UV lithography process, and the area where the chromium layer is not disposed is a light-transmitting area, and forms an exposed area during the subsequent UV lithography process. A schematic diagram of a partial structure of the photolithography mask is shown in FIG. Figure 3 As shown, Figure 3A is the horizontal length of the opaque area of ​​the photolithography mask, that is, the horizontal length of the area where the chromium layer is provided on the glass layer. The shape and size of the opaque area correspond to the horizontal size of the pixel hole in the obtained photoresist layer. B is the horizontal spacing between adjacent opaque areas in the photolithography mask. No chromium layer is provided between adjacent opaque areas, and a transparent area is formed on the photolithography mask, corresponding to the horizontal spacing area between adjacent pixel holes obtained.

[0137] Example 1

[0138] The present embodiment provides a single crystal CsPbBr3 micro-LED light-emitting device, comprising a transparent conductive substrate 1, a hole transport layer 2, a light-emitting layer 3, a photoresist layer 4, a passivation layer 5, an electron transport layer 6, an electron injection layer 7 and an electrode layer 8 stacked in sequence, and its cross-sectional structure schematic diagram is shown as follows: Figure 1 shown.

[0139] Among them, the transparent conductive substrate 1 is ITO conductive glass; the hole transport layer 2 is composed of PEDOT:PSS with a thickness of 40nm; the light-emitting layer 3 is a continuous layer structure, composed of single crystal CsPbBr3 with a thickness of 160nm; the photoresist layer 4 is composed of RFJ-220 negative photoresist with a thickness of 100nm, and contains arrayed pixel holes 41 inside, and the horizontal cross-section of the pixel hole 41 is a square with a side length of 10μm. The pixel hole is a through hole along the thickness direction of the photoresist layer 4, and its structure is a cubic structure. In the horizontal direction, the spacing between adjacent single pixel holes 41 is 3μm. The specific structural schematic diagram is as shown in Figure 2 As shown; a portion of the passivation layer 5 is located on the surface of the light-emitting layer 3 in the pixel hole 41 of the photoresist layer 4, and the other portion is located on the surface of the photoresist layer 4 on the side away from the light-emitting layer 3, and its composition is 2,4,6-triphenyl phenazine oxide (TPPO) with a thickness of 0.5nm; the electron transport layer 6 is located on the passivation layer 5, and its composition is B3PYMPM with a thickness of 25nm; the electron injection layer 7 is composed of LiF with a thickness of 1nm, and the electrode layer 8 is composed of Al with a thickness of 100nm.

[0140] The present invention also provides a method for preparing the above-mentioned single crystal CsPbBr3 micro-LED light-emitting device, the steps of which include:

[0141] (1) ultrasonically cleaning the transparent conductive substrate with glass detergent, deionized water, acetone and ethanol, and obtaining a cleaned transparent conductive substrate after drying; spin-coating PEDOT:PSS on the cleaned transparent conductive substrate at a rotation speed of 4000 rpm for 45 seconds, and then annealing at 150° C. for 20 minutes to obtain a hole transport layer;

[0142] (2) growing a single crystal CsPbBr3 epitaxial light-emitting layer on a sapphire substrate by vapor phase epitaxy under the conditions of N2 gas flow, temperature of 590°C and pressure of 50 Torr, peeling off the single crystal CsPbBr3 epitaxial light-emitting layer on the sapphire substrate in a nitrogen-filled environment to obtain a self-supporting single crystal CsPbBr3 epitaxial light-emitting layer with a thickness of 160 nm, and then transferring the single crystal CsPbBr3 epitaxial light-emitting layer to the hole transport layer formed in step (1) to obtain a continuous light-emitting layer;

[0143] (3) Spin coating RFJ-220 negative photoresist onto the side of the light-emitting layer obtained in step (2) away from the hole transport layer at a rotation speed of 2500 rpm for 30 seconds, then bake at 90° C. for 90 seconds, and then cover the baked photoresist with a photolithography mask, wherein the horizontal cross-section of the opaque area in the photolithography mask is a square with a side length of 10 μm, and the horizontal spacing between adjacent opaque areas is 3 μm. The specific cross-sectional diagram is as follows: Figure 3 As shown, a photoresist with a photolithography mask plate on its surface is exposed for 5 seconds using an ultraviolet lithography machine to form an exposed area and an unexposed area on the photoresist, and then a chlorobenzene developer is used to dissolve the unexposed area on the photoresist. Finally, an isopropanol solvent is used to rinse the photoresist layer, and after drying with nitrogen, a photoresist layer containing pixel holes is obtained, and the light-emitting layer in the pixel holes is not blocked by the photoresist;

[0144] (4) Add a passivation solution to the surface of the light-emitting layer not blocked by the photoresist in the pixel hole obtained in step (3). The passivation solution is 100 mL of 2 mg mL -1 The chlorobenzene solution of TPPO was then spin-coated at 7000 rpm for 1 min to obtain a passivation layer. The prepared substrate was transferred to a vacuum thermal evaporation chamber and heated at 5×10 -4 Pa, a stacked B3PYMPM electron transport layer with a thickness of 25 nm, a LiF electron injection layer with a thickness of 1 nm and an Al electrode layer with a thickness of 100 nm were sequentially prepared on the obtained substrate by evaporation to obtain a CsPbBr3 micro-LED light-emitting device.

[0145] Example 2

[0146] The present embodiment provides a single crystal CsPbBr3 micro-LED light-emitting device, comprising a transparent conductive substrate 1, a hole transport layer 2, a light-emitting layer 3, a photoresist layer 4, a passivation layer 5, an electron transport layer 6, an electron injection layer 7 and an electrode layer 8 stacked in sequence, and its cross-sectional structure schematic diagram is shown as follows: Figure 1 shown.

[0147] Among them, the transparent conductive substrate 1 is ITO conductive glass; the hole transport layer 2 is composed of PEDOT:PSS with a thickness of 30nm; the light-emitting layer 3 is a continuous layer structure, which is composed of single crystal CsPbBr3 with a thickness of 200nm; the photoresist layer 4 is composed of RFJ-220 negative photoresist with a thickness of 50nm, and contains arrayed pixel holes 41 inside, and the horizontal cross-section of the pixel hole 41 is a square with a side length of 20μm. The pixel hole is a through hole along the thickness direction of the photoresist layer 4, and its structure is a cube structure. In the horizontal direction, the spacing between adjacent single pixel holes 41 is 2μm. The specific structural schematic diagram is as shown in Figure 2 As shown; a portion of the passivation layer 5 is located on the surface of the light-emitting layer 3 in the pixel hole 41 of the photoresist layer 4, and the other portion is located on the surface of the photoresist layer 4 on the side away from the light-emitting layer 3, and its composition is 2,4,6-triphenylphenazine oxide (TPPO) with a thickness of 0.7nm; the electron transport layer 6 is located on the passivation layer 5, and its composition is TPBi with a thickness of 20nm; the electron injection layer 7 is composed of LiF with a thickness of 0.5nm; the electrode layer 8 is composed of Al with a thickness of 80nm.

[0148] The present invention also provides a method for preparing the above-mentioned single crystal CsPbBr3 micro-LED light-emitting device, the steps of which include:

[0149] (1) ultrasonically cleaning the transparent conductive substrate with glass detergent, deionized water, acetone and ethanol, and obtaining a cleaned transparent conductive substrate after drying; spin coating PEDOT:PSS on the cleaned transparent conductive substrate at a rotation speed of 4500 rpm for 40 seconds, and then annealing at 100° C. for 30 minutes to obtain a hole transport layer;

[0150] (2) growing a single crystal CsPbBr3 epitaxial light-emitting layer on a sapphire substrate by vapor phase epitaxy under the conditions of N2 gas flow, temperature of 585°C and pressure of 40 Torr, peeling off the single crystal CsPbBr3 epitaxial light-emitting layer on the sapphire substrate in a nitrogen-filled environment to obtain a self-supporting single crystal CsPbBr3 epitaxial light-emitting layer with a thickness of 200 nm, and then transferring the single crystal CsPbBr3 epitaxial light-emitting layer to the hole transport layer formed in step (1) to obtain a continuous light-emitting layer;

[0151] (3) Spin-coat RFJ-220 negative photoresist onto the side of the light-emitting layer obtained in step (2) away from the hole transport layer at a rotation speed of 3000 rpm for 20 seconds, then bake at 80° C. for 100 seconds, and then cover the baked photoresist with a photolithography mask, wherein the horizontal cross-sectional shape of the opaque area on the photolithography mask is a square with a side length of 20 μm, and the horizontal spacing between adjacent opaque areas is 2 μm. The specific cross-sectional schematic diagram is as follows: Figure 3 As shown, a photoresist with a photolithography mask plate on its surface is exposed for 3 seconds using an ultraviolet lithography machine to form an exposed area and an unexposed area on the photoresist, and then a toluene developer is used to dissolve the unexposed area on the photoresist. Finally, an isopropanol solvent is used to rinse the photoresist layer, and after drying with nitrogen, a photoresist layer containing pixel holes is obtained, and the light-emitting layer in the pixel holes is not blocked by the photoresist;

[0152] (4) Add a passivation solution to the surface of the light-emitting layer not blocked by the photoresist in the pixel hole obtained in step (3). The passivation solution is 100 mL of 2 mg mL -1 The chlorobenzene solution of TPPO was then spin-coated at 7000 rpm for 1 min to obtain a passivation layer. The prepared substrate was transferred to a vacuum thermal evaporation chamber and heated at 4 × 10 -4 Pa, a TPBi electron transport layer with a thickness of 20 nm, a LiF electron injection layer with a thickness of 0.5 nm and an Al electrode layer with a thickness of 80 nm were sequentially prepared on the obtained substrate by evaporation to obtain a CsPbBr3 micro-LED light-emitting device.

[0153] Example 3

[0154] The difference between this embodiment and embodiment 1 is that the side length of a single horizontal cross section of a pixel hole 41 in the photoresist layer 4 provided in this embodiment is 50 μm, and the spacing between adjacent single pixel holes 41 in the horizontal direction is 4 μm. Accordingly, the cross section of the opaque area in the photolithography mask is a square with a side length of 50 μm, and the spacing between adjacent opaque areas is 4 μm. The rest of the contents are the same as those in embodiment 1.

[0155] Example 4

[0156] The present embodiment provides a single crystal CsPbClBr2 micro-LED light-emitting device, including a transparent conductive substrate 1, a hole transport layer 2, a light-emitting layer 3, a photoresist layer 4, a passivation layer 5, an electron transport layer 6, an electron injection layer 7 and an electrode layer stacked in sequence, and its cross-sectional structure schematic diagram is shown as follows: Figure 1 shown.

[0157] Among them, the transparent conductive substrate 1 is ITO conductive glass; the hole transport layer 2 is composed of PEDOT:PSS with a thickness of 50nm; the light-emitting layer 3 is a continuous layer structure, composed of single crystal CsPbClBr2 with a thickness of 180nm; the photoresist layer 4 is composed of RFJ-220 negative photoresist with a thickness of 200nm, and contains arrayed pixel holes 41 inside, and the horizontal cross-section of the pixel hole 41 is a square with a side length of 50μm. The pixel hole is a through hole along the thickness direction of the photoresist layer 4, and its structure is a cubic structure. In the horizontal direction, the spacing between adjacent single pixel holes 41 is 5μm. The specific structural schematic diagram is as shown in Figure 2 As shown; a portion of the passivation layer 5 is located on the surface of the light-emitting layer 3 in the pixel hole 41 of the photoresist layer 4, and the other portion is located on the surface of the photoresist layer 4 on the side away from the light-emitting layer 3, and its composition is 2,4,6-triphenyl phenazine oxide (TPPO) with a thickness of 1 nm; the electron transport layer 6 is located on the passivation layer 5, and its composition is B3PYMPM with a thickness of 40 nm; the electron injection layer 7 is composed of LiF with a thickness of 3 nm; the electrode layer 8 is composed of Al with a thickness of 120 nm.

[0158] The present invention also provides a method for preparing a single crystal CsPbClBr2 micro-LED light-emitting device, the steps of which include:

[0159] (1) ultrasonically cleaning the transparent conductive substrate with glass detergent, deionized water, acetone and ethanol, and obtaining a cleaned transparent conductive substrate after drying; spin coating PEDOT:PSS on the cleaned transparent conductive substrate at a rotation speed of 3500 rpm for 50 seconds, and then annealing at 200° C. for 10 minutes to obtain a hole transport layer;

[0160] (2) growing a CsPbClBr2 single crystal epitaxial light-emitting layer on a sapphire substrate by vapor phase epitaxy under the conditions of N2 gas flow, temperature of 610°C and pressure of 100 Torr, peeling off the CsPbClBr2 single crystal epitaxial light-emitting layer on the sapphire substrate in a nitrogen-filled environment to obtain a self-supporting CsPbClBr2 single crystal epitaxial light-emitting layer with a thickness of 180 nm, and then transferring the CsPbClBr2 single crystal epitaxial light-emitting layer to the hole transport layer formed in step (1) to obtain a continuous light-emitting layer;

[0161] (3) Spin coating RFJ-220 negative photoresist at a rotation speed of 2000 rpm onto the side of the light-emitting layer obtained in step (2) away from the hole transport layer for 40 seconds, then bake at 100° C. for 80 seconds, and then cover the baked photoresist with a photolithography mask, wherein the horizontal cross-sectional shape of the opaque area on the photolithography mask is a square with a side length of 50 μm, and the horizontal spacing between adjacent opaque areas is 5 μm. The specific cross-sectional schematic diagram is as follows: Figure 3 As shown, a photoresist with a photolithography mask plate on its surface is exposed for 6 seconds using an ultraviolet lithography machine to form an exposed area and an unexposed area on the photoresist, and then an m-xylene developer is used to dissolve the unexposed area on the photoresist. Finally, an acetone solvent is used to rinse the photoresist layer, and after drying with nitrogen, a photoresist layer containing pixel holes is obtained, and the light-emitting layer in the pixel holes is not blocked by the photoresist;

[0162] (4) Add 1 mL of passivation solution to the surface of the light-emitting layer not blocked by the photoresist in the pixel hole obtained in step (3). The passivation solution is 100 mL of 2 mg mL -1 The TPPO solution in m-xylene was then spin-coated at 6000 rpm for 1 min to obtain a passivation layer. The prepared substrate was transferred to a vacuum thermal evaporation chamber and heated at 6×10 -4 Pa, a stacked B3PYMPM electron transport layer with a thickness of 40 nm, a LiF electron injection layer with a thickness of 3 nm and an Al electrode layer with a thickness of 120 nm were prepared in sequence by evaporation to obtain a CsPbClBr2 micro-LED light-emitting device.

[0163] Example 5

[0164] The difference between this embodiment and embodiment 1 is that the thickness of the photoresist layer provided in this embodiment is 40 nm. Accordingly, the preparation method provided is to spin-coat the RFJ-220 negative photoresist at a rotation speed of 3200 rpm onto the side of the light-emitting layer away from the hole transport layer, and the spin-coating time is 15 s. The rest of the contents are the same as those in embodiment 1.

[0165] Example 6

[0166] The difference between this embodiment and embodiment 1 is that the thickness of the photoresist layer provided in this embodiment is 210 nm. Accordingly, the preparation method provided is to spin-coat the RFJ-220 negative photoresist at a rotation speed of 1800 rpm onto the side of the light-emitting layer away from the hole transport layer, and the spin-coating time is 45 s. The rest of the contents are the same as those in embodiment 1.

[0167] Example 7

[0168] The difference between this embodiment and embodiment 1 is that the composition of the photoresist layer provided in this embodiment is a positive photoresist of model RZX-3038. Correspondingly, in the preparation method provided, a photolithography mask with a light-transmitting area and a light-impermeable area exchanged is used, and the developer used is a 6.71wt% tetramethylammonium hydroxide (TMAH) alkaline solution, and the rinse solution is deionized water. The rest of the contents are the same as those in embodiment 1.

[0169] Example 8

[0170] The difference between this embodiment and embodiment 1 is that the passivation layer 5 is omitted in the light emitting device provided in this embodiment. Accordingly, in the preparation method provided, the dripping and spin coating of the chlorobenzene solution of TPPO in step (IV) are omitted. The rest of the contents are the same as those in embodiment 1.

[0171] Comparative Example 1

[0172] The difference between this comparative example and Example 1 is that the light emitting device provided in this comparative example omits the photoresist layer. The rest of the contents are the same as Example 1.

[0173] Comparative Example 2

[0174] The difference between this comparative example and Example 1 is that: the photoresist layer of the light-emitting device provided in this comparative example does not have pixel holes, and is a completely continuous photoresist layer, and the electron transport layer in the light-emitting device is located on the photoresist layer. The rest of the contents are the same as Example 1.

[0175] Comparative Example 3

[0176] The difference between this comparative example and Example 1 is that in the preparation method of the light-emitting device provided in this comparative example, after the photoresist layer containing pixel holes is prepared in step (3), it is etched with an aqueous solution of hydrobromic acid for 5 seconds, and then the residual photoresist is removed with acetone. After rinsing and drying, a patterned light-emitting layer is obtained. A passivation solution is dripped on the surface of the light-emitting layer. The passivation solution is 100 mL of 2 mg mL -1 The chlorobenzene solution of TPPO was then spin-coated to obtain a passivation layer. The prepared substrate was transferred to a vacuum thermal evaporation chamber and heated at 5×10 -4 Pa, a stacked B3PYMPM electron transport layer with a thickness of 25 nm, a LiF electron injection layer with a thickness of 1 nm and an Al electrode layer with a thickness of 100 nm were prepared in sequence by evaporation to obtain the light emitting device. The rest of the contents are the same as those in Example 1.

[0177] In a nitrogen-filled glove box, a fluorescence / external quantum efficiency measurement system was used. The material integrating sphere was used to measure the luminous brightness, maximum external quantum efficiency and luminous stability of the light-emitting devices in Examples 1-8 and Comparative Examples 1-3. The specific test method and setting parameters are as follows:

[0178] (1) Maximum luminous brightness: The luminous brightness curve changes with voltage, with a step size of 0.2V. The luminous area is calculated based on the luminous pixel unit, in cd m -2 ;

[0179] (2) Maximum external quantum efficiency: EQE variation curve with external voltage, step size 0.2V, luminous area calculated based on luminous pixel unit, unit %;

[0180] (3) Luminescence stability: The device has a luminous brightness of 100 cd / m 2 The time required for the light to decay to half brightness, in h.

[0181] The test results are shown in Table 1:

[0182] Table 1

[0183]

[0184] The test results show that:

[0185] (1) It can be seen from Examples 1 to 4 that the light-emitting device provided by the present invention has a photoresist layer disposed between a continuous light-emitting layer and an electron transport layer. The pixel holes contained in the photoresist layer form a photoresist-blocked area and a photoresist-unblocked area on the surface of the light-emitting layer, thereby achieving patterned isolation of pixels of the light-emitting layer. While ensuring the integrity of the light-emitting layer, ultra-high resolution can be obtained, so that the light-emitting device can obtain bright, efficient and uniform light emission.

[0186] Among them, Figure 4-6 Partial electroluminescence images of single crystal CsPbBr3 micro-LED light-emitting devices of Examples 1-3 are given as well as Figure 7 From the schematic diagram of partial electroluminescence of the single crystal CsPbClBr2 micro-LED light-emitting device of Example 4, it can be seen that the pixel light-emitting area of ​​the light-emitting device is independent and has high light-emitting intensity.

[0187] Figure 8 This is the current density / brightness-voltage relationship curve of the single crystal CsPbBr3 micro LED light-emitting device of Example 1. It can be seen from the figure that the current density and brightness of the light-emitting device increase with increasing voltage.

[0188] Fig. 9The relationship curve between EQE (external quantum efficiency) and brightness of the single crystal CsPbBr3 micro LED light emitting device of Example 1 is shown in the figure. As can be seen from the figure, the light emitting device has a brightness of 7×10 4 cd m -2 The maximum external quantum efficiency reaches 16.1%.

[0189] Fig.10 The curve of the relationship between the luminous brightness of the single crystal CsPbBr3 micro LED light-emitting device in Example 1 and the change of voltage. It can be seen from the figure that the voltage increases from 2.8V to 6.0V with an interval of 0.4V between each curve. As the voltage increases, the luminous brightness of the light-emitting device increases.

[0190] Fig.11 The current density / brightness-voltage relationship curve of the single crystal CsPbClBr2 micro LED light-emitting device of Example 4 is shown in the figure. As can be seen from the figure, the current density and brightness of the light-emitting device increase with the increase of voltage, and the maximum brightness is 3.0×10 5 cd m -2 .

[0191] Fig.12 This is the EQE (external quantum efficiency)-brightness relationship curve of the single crystal CsPbClBr2 micro LED light-emitting device of Example 4. It can be seen from the figure that the maximum external quantum efficiency of the light-emitting device is 13.84%.

[0192] (2) It can be seen from Examples 1 to 5 and 6 that in the present invention, if the thickness of the photoresist layer is too thin, the photoresist blocking will be insufficient and partial leakage will occur; if the thickness of the photoresist layer is too thick, the photoresist edge will be seriously tailed, the interface will not be steep, and the problem of pixel crosstalk will occur.

[0193] (3) It can be seen from Examples 1 to 7 that if a positive photoresist is used in the present invention, since the developer of the positive photoresist is an alkaline solution and the rinse solution is water, the light-emitting layer is structurally damaged, and the light-emitting brightness and external quantum efficiency of the light-emitting device are low.

[0194] (4) It can be seen from Examples 1 to 8 that if the passivation layer is omitted in the present invention, the surface defect density of the light-emitting layer is high, and the luminous brightness and external quantum efficiency are low.

[0195] (5) It can be seen from Example 1 and Comparative Example 1 that if the photoresist layer is omitted in the present invention, the planar device cannot emit light due to short circuit.

[0196] (6) It can be seen from Example 1 and Comparative Example 2 that if pixel holes are not provided in the photoresist layer of the present invention, the light-emitting device will be blocked by the insulating photoresist layer during electron transmission and cannot recombine with holes in the light-emitting layer, and the device will not emit light.

[0197] (7) It can be seen from Example 1 and Comparative Example 3 that if the light-emitting layer is directly etched in the present invention, it will cause great damage to the light-emitting layer, and the light-emitting intensity and external quantum efficiency of the light-emitting device will be low.

[0198] In summary, the light-emitting device provided by the present invention has a photoresist layer disposed between a continuous light-emitting layer and an electron transport layer, and the pixel holes contained in the photoresist layer form a region blocked by the photoresist and a region not blocked by the photoresist on the surface of the light-emitting layer, thereby realizing patterned isolation of the pixels of the light-emitting layer, ensuring the integrity of the light-emitting layer, and being able to obtain ultra-high resolution, so that the light-emitting device can obtain bright, efficient and uniform light emission. The preparation method provided by the present invention uses an indirect photolithography method that etches the photoresist layer on the light-emitting layer using photolithography technology, and can achieve patterned isolation of the pixels of the light-emitting layer without directly etching the light-emitting layer in the light-emitting device, thereby avoiding structural defects and surface damage to the light-emitting layer caused by direct etching. The light-emitting device with controllable pixel size and ultra-high resolution prepared by the preparation method of the present invention can achieve bright, efficient and uniform light emission.

[0199] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A light emitting device, characterized in that: The light-emitting device comprises a transparent conductive substrate, a hole transport layer, a light-emitting layer, a photoresist layer, an electron transport layer and an electrode layer, wherein the photoresist layer is located between the light-emitting layer and the electron transport layer, the light-emitting layer is a continuous layer structure, and the photoresist layer comprises pixel holes.

2. The light emitting device according to claim 1, characterized in that: The light emitting device is a micro light emitting device; Preferably, the light-emitting device comprises a transparent conductive substrate, a hole transport layer, a light-emitting layer, a photoresist layer, an electron transport layer and an electrode layer which are stacked in sequence; Preferably, the composition of the light-emitting layer includes single crystal material; Preferably, the composition of the photoresist layer includes negative photoresist; Preferably, the thickness of the photoresist layer is 50-200 nm; Preferably, in the photoresist layer, the pixel holes are arranged in an array; Preferably, the pixel hole is a through hole along the thickness direction of the photoresist layer; Preferably, the hole structure of the pixel hole is a cubic structure; Preferably, the cross-sectional shape of the single pixel hole includes any one of a square, a rectangle, a diamond, a triangle or a circle, preferably a square; Preferably, when the cross-section of the single pixel hole is in any one of a square, a rectangle, a rhombus or a triangle, the side length of the cross-section of the single pixel hole is 2-100 μm; Preferably, when the cross-section of the single pixel hole is circular, the diameter of the cross-section of the single pixel hole is 2-100 μm; Preferably, in the horizontal direction, the spacing between adjacent single pixel holes is 2-50 μm.

3. The light emitting device according to claim 1 or 2, characterized in that: The light emitting device further comprises a passivation layer, a portion of the passivation layer is located on the surface of the light emitting layer in the pixel hole of the photoresist layer, and another portion of the passivation layer is located on the surface of the photoresist layer on a side away from the light emitting layer; Preferably, the composition of the passivation layer includes any one of 2,4,6-triphenylphenazine oxide (TPPO) or tris(4-fluorophenyl)phosphine oxide (TFPPO); Preferably, the thickness of the passivation layer is comprised between 0.5 and 2 nm; Preferably, the electron transport layer is located on a surface of the passivation layer away from the light-emitting layer; Preferably, an electron injection layer is further provided between the electron transport layer and the electrode layer.

4. A method for preparing a light-emitting device according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: A hole transport layer and a continuous light-emitting layer are sequentially prepared on a transparent conductive substrate; a photoresist layer containing pixel holes is prepared on the side of the light-emitting layer away from the hole transport layer by using a photolithography process, and then an electron transport layer and an electrode layer are sequentially formed on the substrate containing the photoresist layer to obtain the light-emitting device.

5. The preparation method according to claim 4, characterized in that: The hole transport layer is prepared by spin coating and then annealing; Preferably, the specific preparation process of the light-emitting layer includes: growing a single crystal epitaxial light-emitting layer on a substrate using a vapor phase epitaxy method, peeling off the single crystal epitaxial light-emitting layer on the substrate in a nitrogen-filled environment to obtain a self-supporting single crystal epitaxial light-emitting layer, and then transferring the self-supporting single crystal epitaxial light-emitting layer to the hole transport layer to obtain a continuous light-emitting layer.

6. The preparation method according to claim 4 or 5, characterized in that: The photolithography process includes coating, baking, exposure, development and rinsing; Preferably, in the photolithography process, the coating method includes spin coating with photoresist; Preferably, the photoresist comprises a negative photoresist; Preferably, in the photolithography process, the rotation speed of the spin coating is 2000-3000 rpm; Preferably, in the photolithography process, the spin coating time is 20-40s; Preferably, the baking temperature is 80-100°C; Preferably, the baking time is 80-100s.

7. The preparation method according to claim 6, characterized in that: The specific process of the exposure includes: using a photolithography mask plate to cover the baked photoresist, and then irradiating the photoresist with the photolithography mask plate on the surface through an ultraviolet photolithography machine to form an exposed area and an unexposed area on the photoresist; Preferably, the exposure time is 3-6s; Preferably, the specific process of the development includes: dissolving the unexposed area on the photoresist using a developer; Preferably, the developer comprises any one of chlorobenzene, toluene, dichlorobenzene or m-xylene, or a combination of at least two thereof; Preferably, the solvent used for rinsing includes any one of isopropanol or acetone; Preferably, nitrogen gas is used to blow dry after rinsing.

8. The preparation method according to any one of claims 5 to 7, characterized in that: After the photoresist layer is prepared, the passivation layer is also prepared; Preferably, the specific process for preparing the passivation layer comprises: adding a passivation liquid dropwise onto the surface of the light-emitting layer in the pixel hole, and then spin coating to obtain the passivation layer; Preferably, during the preparation of the passivation layer, the spin coating speed is 6000-7000 rpm; Preferably, during the preparation of the passivation layer, the spin coating time is 0.5-5 min; Preferably, the solute of the passivation solution includes any one of 2,4,6-triphenylphenazine oxide (TPPO) or tris(4-fluorophenyl)phosphine oxide (TFPPO); Preferably, the solvent of the passivation solution includes any one of chlorobenzene, dichlorobenzene or m-xylene.

9. The preparation method according to any one of claims 5 to 8, characterized in that: The electron transport layer and the electrode layer are prepared by an evaporation process; Preferably, the evaporation is performed in a vacuum environment; Preferably, the evaporation pressure is 3×10 -4 -6×10 -4 Pa; Preferably, an electron injection layer is further provided on the side of the electron transport layer close to the electrode layer; Preferably, the electron injection layer is disposed on the electron transport layer by evaporation; Preferably, the electrode layer is disposed on the electron injection layer by evaporation.

10. An application of the light emitting device according to any one of claims 1 to 3, characterized in that: The light-emitting device is applied in the fields of optical communication, wearable devices, virtual reality or augmented reality.

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