Light-emitting apparatus, preparation method and electronic device

Abstract

A light-emitting apparatus, comprising a substrate (1), a first electrode (2), a light-emitting layer (3) and a second electrode (4), wherein the first electrode (2) is located on the substrate (1), and the light-emitting layer (3) is located between the first electrode (2) and the second electrode (4). The light-emitting layer (3) comprises a first unit (301) and a second unit (302), wherein the first unit (301) is used for emitting light within a first wavelength range, and the second unit (302) is used for emitting light within a second wavelength range, the first wavelength range being lower than the second wavelength range; and the first unit (301) is close to the one of the first electrode (2) and the second electrode (4) that serves as a cathode. Further disclosed are a preparation method for a light-emitting apparatus, and an electronic device.

Description

Light-emitting device, preparation method and electronic device Technical Field

[0001] The present application relates to the field of optoelectronic devices, and in particular to a light-emitting device, a preparation method and an electronic device. Background Art

[0002] Light-emitting devices, such as light-emitting diodes (LEDs), are widely used in the display field. The manufacturing process of these devices can affect device performance, particularly causing blue light loss. Technical issues

[0003] The purpose of this application is to provide a light-emitting device, a preparation method and an electronic device, which can solve the technical problem of poor performance of existing light-emitting devices. Technical Solutions

[0004] According to the first embodiment of the present application, the light emitting device includes:

[0005] substrate;

[0006] a first electrode, a light-emitting layer, and a second electrode, wherein the first electrode is located on the substrate, and the light-emitting layer is located between the first electrode and the second electrode;

[0007] The light-emitting layer includes a first unit and a second unit arranged along a first direction of the substrate; the first unit is used to emit light in a first wavelength range, and the second unit is used to emit light in a second wavelength range, and the first wavelength range is lower than the second wavelength range;

[0008] The first unit includes a first layer and a second layer arranged along a first direction of the substrate, the orthographic projection of the first layer on the substrate overlaps with the orthographic projection of the second unit on the substrate, and the first unit is closer to one of the first electrode and the second electrode as a cathode than the second unit. Optionally, the first layer is closer to one of the first electrode and the second electrode as a cathode than the second unit.

[0009] Optionally, the light-emitting layer includes a third unit arranged along the first direction of the substrate, and the third unit is used to emit light in a third wavelength range, and the first wavelength range is lower than the third wavelength range.

[0010] Optionally, the orthographic projection of the first layer on the substrate overlaps with the orthographic projection of the third unit on the substrate.

[0011] Optionally, the first layer is closer to the first electrode and the second electrode than the third unit and serves as one of the cathodes.

[0012] Optionally, the light-emitting device includes a plurality of isolation structures, wherein the isolation structures are located on the substrate, and the light-emitting layer is divided into a plurality of light-emitting units by the isolation structures.

[0013] Optionally, the height of the isolation structure is not lower than the height of the second unit.

[0014] Optionally, the light-emitting device includes a first functional layer, which is located between the first electrode and the light-emitting layer, and the first functional layer includes at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, an electron blocking layer, and a buffer layer.

[0015] Optionally, the light-emitting device includes a second functional layer, which is located between the light-emitting layer and the second electrode, and the second functional layer includes at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, an electron blocking layer, and a buffer layer.

[0016] Optionally, the isolation structure has a first surface, and the material of the first surface is amphiphilic.

[0017] Optionally, the first unit includes a first luminescent material, and the second unit includes a second luminescent material; the first unit includes the second luminescent material, and the mass percentage of the second luminescent material in the first unit is ≤5% based on the mass of the first unit.

[0018] Optionally, the third unit includes a third luminescent material, the first unit includes the third luminescent material, and based on the mass of the first unit, the mass percentage of the third luminescent material in the first unit is ≤5%.

[0019] Optionally, the second unit includes a third luminescent material, and based on the mass of the second unit, the mass percentage of the third luminescent material in the second unit is ≤5%.

[0020] Optionally, the third unit includes a second luminescent material, and based on the mass of the third unit, the mass percentage of the second luminescent material in the third unit is ≤5%.

[0021] According to the second embodiment of the present application, the method for preparing a light-emitting device includes the following steps:

[0022] providing a substrate;

[0023] forming a first electrode, wherein the first electrode is located on the substrate;

[0024] A light-emitting layer is formed, where the light-emitting layer is located on the first electrode. The preparation of the light-emitting layer includes:

[0025] forming a first unit and a second unit arranged along a first direction of the substrate, wherein the first unit is configured to emit light within a first wavelength range, and the second unit is configured to emit light within a second wavelength range, wherein the first wavelength range is lower than the second wavelength range; the first unit comprises a first layer and a second layer arranged along the first direction of the substrate, wherein an orthographic projection of the first layer on the substrate overlaps with an orthographic projection of the second unit on the substrate;

[0026] forming a second electrode, wherein the second electrode is located on the light-emitting layer;

[0027] The first unit is closer to one of the first electrode and the second electrode as a cathode than the second unit.

[0028] Optionally, the preparation of the second unit includes:

[0029] forming a second material layer containing a second material on the first electrode, forming an exposed area and a non-exposed area in the second material layer, and removing the second material in the exposed area or the second material in the non-exposed area by a first solvent to obtain a second unit;

[0030] The preparation of the first unit includes: forming a first material layer containing a first material on the first electrode to obtain the first unit.

[0031] Optionally, the preparation of the light-emitting layer includes: forming a third unit arranged along the first direction of the substrate, the third unit being configured to emit light in a third wavelength range, the first wavelength range being lower than the third wavelength range.

[0032] Optionally, the preparation of the third unit includes: forming a third material layer containing a third material on the first electrode, forming an exposed area and a non-exposed area of ​​the third material layer, and removing the third material in the exposed area or the third material in the non-exposed area by a second solvent to obtain the third unit.

[0033] Optionally, the polarity of the third solvent is different from the polarity of the second material.

[0034] According to the electronic device in the third embodiment of the present application, it includes the above-mentioned light-emitting device, or includes a light-emitting device obtained by the above-mentioned method for preparing the light-emitting device. Beneficial effects

[0035] The light-emitting device according to the embodiment of the present application has at least the following technical effects:

[0036] In the light-emitting device of the present application, the first unit is used to emit light in a first wavelength range, and the second unit is used to emit light in a second wavelength range, where the first wavelength range is lower than the second wavelength range; the first unit is close to the first electrode and the second electrode serves as a cathode. The light-emitting performance of the light-emitting device is improved by changing the structure of the light-emitting device of the present application;

[0037] In the method for preparing the light-emitting device of the present application, the light-emitting performance of the light-emitting device is improved by changing the method for preparing the light-emitting unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0039] FIG1 is a schematic structural diagram of a light-emitting device in some embodiments of the present application;

[0040] FIG2 is a flowchart of the preparation of a light-emitting device in some embodiments of the present application;

[0041] FIG3 is a flow chart of the preparation of a light-emitting device in some embodiments of the present application;

[0042] FIG4 is a flow chart of preparing a light-emitting device in some embodiments of the present application;

[0043] FIG5 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0044] FIG6 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0045] FIG7 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0046] FIG8 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0047] FIG9 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0048] FIG10 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0049] FIG11 is a flowchart of preparing a light-emitting device in some embodiments of the present application;

[0050] FIG12 is a schematic structural diagram of a light-emitting device in some embodiments of the present application;

[0051] FIG13 is an electroluminescence spectrum of a light-emitting device with different light-emitting layer overlaps in this application;

[0052] FIG14 is an electroluminescence spectrum of a light-emitting device with different light-emitting layer overlaps in this application;

[0053] FIG15 is an electroluminescence spectrum of a light-emitting device with different light-emitting layer overlaps in this application;

[0054] FIG16 shows the electroluminescence spectra of the light-emitting devices with different light-emitting layer overlaps in this application;

[0055] FIG17 shows the electroluminescence spectra of the light-emitting devices with different light-emitting layer overlaps in this application;

[0056] FIG18 shows the electroluminescence spectra of the light-emitting devices with different light-emitting layer overlaps in this application;

[0057] In the figure, 1-substrate, 101-isolation structure, 110-first surface, 2-first electrode, 3-light-emitting layer, 301-first unit, 302-second unit, 303-third unit, 4-second electrode, 5-first functional layer, 501-hole injection layer, 502-hole transport layer, 6-second functional layer. Modes for Carrying Out the Invention

[0058] The following, in conjunction with the accompanying drawings, provides a clear and complete description of the technical solutions in the embodiments of the present application. It should be noted that the described embodiments are only a portion of the embodiments of the present application, and not all of the embodiments. All other embodiments derived by persons skilled in the art based on the embodiments of the present application without inventive effort are within the scope of protection of the present application. Furthermore, in the description of the present application, the term "including" means "including but not limited to." The terms "first," "second," and "third," etc., are used merely as designations and do not impose numerical requirements or establish a sequence. Various embodiments of the present application may be presented in the form of a range. It should be understood that describing in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application. Therefore, the range description should be considered to specifically disclose all possible subranges and individual numerical values ​​within the range. For example, a range description of 1 to 6 should be considered to specifically disclose subranges, such as 1 to 3, 1 to 4, 1 to 5, 2 to 4, 2 to 6, 3 to 6, etc., as well as individual numerical values ​​within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

[0059] References to "left," "right," "front," "back," "top," "bottom," "up," "down," "high," "low," and the like in this application, if any, are for descriptive purposes and are not necessarily intended to describe fixed relative positions. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments disclosed herein described herein, for example, can operate in orientations other than those shown or otherwise described herein. For example, when the device in the accompanying drawings is inverted, a feature previously described as being "above" another feature may now be described as being "below" the other feature. The device may also be oriented in other ways (rotated 90 degrees or in other orientations), in which case relative spatial relationships will be interpreted accordingly. References to an element being "above" another element in this application may be directly above the other element, or one or more intervening elements may be present. In addition, the drawings in this application only illustrate cross-sectional views of a portion of a light-emitting device. The first direction X in this application is transverse, the second direction Y is longitudinal, and the second direction Y is also the thickness direction of each structure. The first direction X and the second direction Y intersect, or the first direction X and the second direction Y are perpendicular or relatively perpendicular.

[0060] In the present application, negative terms such as "does not include" include absolutely not including and relatively not including. Relatively not including means that the specific material contained does not exert its function.

[0061] The luminescence performance of the blue light-emitting unit plays a crucial role in the quality of the light-emitting device. The applicant has discovered that when a light-emitting device has two light-emitting units and the two light-emitting units emit light in different wavelength ranges, the light-emitting unit emitting light in the smaller wavelength range is closer to the cathode, so it does not affect the luminescence performance of the other light-emitting unit it covers. The main principle is to control the carriers flowing into the anode and cathode sides to prevent or not easily stay in the first layer of the first unit used to emit short wavelengths, so that the first layer does not emit light. Those skilled in the art can achieve this by controlling the energy levels of the materials of each functional layer and the light-emitting material. For example, in quantum dot electroluminescent devices, the electron injection capability of the electron transport layer and / or electron injection layer materials is currently greater than the hole injection capability of the hole transport layer and / or hole injection layer materials. Therefore, the quantum dot layer emits more light near the hole transport layer. When the band gap of the quantum dot near the electron transport layer is at least 0.2 eV greater than the band gap of the quantum dot near the hole transport layer, the electron and hole carriers are less likely to stay in these quantum dots with larger band gaps, and the carriers will not recombine and emit light there. As shown in FIG1 , an embodiment of the present application provides a light-emitting device, comprising: a substrate 1, a first electrode 2, a light-emitting layer 3, and a second electrode 4. The first electrode 2 is located on the substrate 1, and the light-emitting layer 3 is located between the first electrode 2 and the second electrode 4.

[0062] In some embodiments, the light-emitting layer 3 includes a first unit 301 and a second unit 302 arranged along a first direction X of the substrate 1; the first unit 301 is configured to emit light within a first wavelength range, and the second unit 302 is configured to emit light within a second wavelength range, where the first wavelength range is lower than the second wavelength range; the first unit 301 is positioned adjacent to the first electrode 2 and the second electrode 4, serving as a cathode. In this application, the first unit 301 is positioned adjacent to the cathode, emitting light within the first wavelength range. When the orthographic projections of the first unit 301 and the second unit 302 overlap on the substrate 1, the overlapping portion of the first unit 301 with the second unit 302 does not affect the light-emitting performance of the second unit 302.

[0063] In some embodiments, the band gap of the quantum dots of the first luminescent material in the first cell 301 is larger than the band gap of the quantum dots of the second luminescent material in the second cell 302 .

[0064] In some embodiments, the quantum dot band gap energy E1 of the first light-emitting material and the quantum dot band gap energy E2 of the second light-emitting material satisfy: E1-E2≥0.2 eV.

[0065] In some embodiments, the first wavelength range is 400-500 nm, that is, the first unit is used to emit blue light, and the second wavelength range can be 500-600 nm, or the second wavelength range can be 600-780 nm, and the second unit is used to emit green light or red light. When the first wavelength range is 500-600 nm, the second wavelength range can be 600-780 nm.

[0066] In some embodiments, the first unit 301 includes a first layer 3011 and a second layer 3012, and the first layer 3011 and the second layer 3012 are located in the same layer or different layers (relative to the height of the substrate 1) of the light-emitting device. The orthographic projection of the first layer 3011 on the substrate 1 overlaps with the orthographic projection of the second unit 302 on the substrate 1. In the present application, the orthographic projections of the first layer 3011 and the second unit 302 on the substrate 1 may partially overlap or completely overlap. In other embodiments, the orthographic projection of the first layer 3011 on the substrate 1 covers the orthographic projection of the second unit 302 on the substrate 1. The first layer 3011 is closer to the first electrode 2 and the second electrode 4 as one of the cathodes than the second unit 302. When the first layer 3011 is located close to the cathode, the first layer 3011 on the second unit 302 does not affect the luminescent performance of the second unit 302. The first layer 3011 overlapping with the second unit 302 does not emit light, and the second layer 3012 emits light within the first wavelength range.

[0067] In some embodiments, the light-emitting layer 3 includes a third unit 303, which is configured to emit light in a third wavelength range, where the first wavelength range is lower than the third wavelength range. In other embodiments, the third wavelength range is different from the second wavelength range. In other embodiments, the first wavelength range is 400-500 nm, the first unit 301 is configured to emit blue light, the second wavelength range is 500-600 nm, the second unit 302 is configured to emit green light, the third wavelength range is 600-780 nm, and the third unit 303 is configured to emit red light. In other embodiments, the first wavelength range is 400-500 nm, the first unit 301 is configured to emit blue light, the second wavelength range is 600-780 nm, the second unit 302 is configured to emit red light, the third wavelength range is 500-600 nm, and the third unit 303 is configured to emit green light. In some embodiments, the first wavelength range is 410-490 nm, 420-480 nm, or 450-480 nm.

[0068] In some embodiments, the orthographic projection of the first layer 3011 on the substrate 1 overlaps with the orthographic projection of the third unit 303 on the substrate 1. The first layer 3011 is closer to the first electrode 2 and the second electrode 4, which serves as the cathode, than the third unit 303. The portion of the first layer 3011 overlapping with the third unit 303 does not affect the luminescence performance of the second unit 302. In some embodiments, the orthographic projection of the first layer 3011 on the substrate 1 covers the orthographic projection of the third unit 303 on the substrate 1. That is, the orthographic projection of the first layer 3011 on the substrate 1 completely covers the orthographic projection of the third unit 303 on the substrate 1.

[0069] In some embodiments, the substrate 1 is a pixel substrate having an array of circuit designs, and each pixel is independently controlled by a thin film transistor.

[0070] In some embodiments, a plurality of isolation structures 101 are provided on the substrate 1. The isolation structures 101 are located on the substrate 1. The light-emitting layer 3 is divided into a plurality of light-emitting units by the isolation structures 101. The areas surrounded by the isolation structures 101 form different sub-pixel regions. In some specific embodiments, the different sub-pixel regions are divided into a first pixel region, a second pixel region, and a third pixel region. The first pixel region is provided with a first light-emitting material for emitting light within a first wavelength range, the second pixel region is provided with a second light-emitting material for emitting light within a second wavelength range, and the third pixel region is provided with a third light-emitting material for emitting light within a third wavelength range. Taking the first pixel region as a blue pixel region BP, the second pixel region as a red pixel region RP, and the third pixel region as a green pixel region GP as an example, the first pixel region includes a blue quantum dot layer, the second pixel region includes a red quantum dot layer and a blue quantum dot layer superimposed on the red quantum dot layer, and the third pixel region includes a green quantum dot layer and a blue quantum dot layer superimposed on the green quantum dot layer.

[0071] In some embodiments, the first layer 3011 is composed of a blue quantum dot layer superimposed on a red quantum dot layer and a blue quantum dot layer superimposed on a green quantum dot layer, and the second layer 3012 is composed of a blue quantum dot layer located in the first pixel region. The first layer and / or the second layer can be continuous layers or layers separated by isolation structure 101. Although the first layer 3011 contains blue quantum dot material, it does not emit light. The blue quantum dot layer located in the second layer 3012 provides the blue light required by the light-emitting device.

[0072] In some embodiments, the first unit 301 is entirely disposed in the light-emitting device, and the portion thereof overlapping with the second unit 302 and the third unit 303 does not emit light.

[0073] In some embodiments, the height of the isolation structure 101 is not less than the height of the second unit 302. When the light-emitting device is in an upright structure, the height of the isolation structure 101 can be the same as the larger of the second unit 302 or the third unit 303, thereby reducing the impact of the excessive height of the isolation structure 101 on device performance. In other embodiments, when the light-emitting device is in an inverted structure, the height of the isolation structure 101 is the same as or higher than the sum of the heights of the first unit 301 and the second unit 302, or the sum of the heights of the isolation structure 101 and the third unit 303, whichever is larger. In some embodiments, the height direction of the present application is the direction in which the second direction Y extends.

[0074] In some embodiments, the first, second, or third material layers of the present application contain a photosensitive material, and the photosensitive material includes at least one of a photosensitive crosslinker, a photopolymerization initiator, and a photoacid generator. In some embodiments, at least one of the first, second, or third material layers of the present application does not contain a photosensitive material; or the first, second, or third unit is not formed by exposure (photolithography).

[0075] In some embodiments, the photosensitive crosslinker includes at least one of an azide compound and a free radical photoinitiator.

[0076] In some embodiments, the photosensitive crosslinker includes an azide compound, such as a phenyl azide compound, such as (1E,4E)-1,5-bis(4-azido-2,3,5,6-tetrafluorophenyl)penta-1,4-dien-3-one.

[0077] In some embodiments, the photosensitive crosslinker includes a free radical photoinitiator, such as ethyl 2,4,6-trimethylbenzoylphenylphosphonate.

[0078] In some embodiments, the substrate of the present application has multiple isolation structures 101, and the light-emitting layer 300 is divided into multiple light-emitting units by the isolation structures 101. In other embodiments, the isolation structure has a first surface 110, and the material of the first surface 110 is amphiphilic (hydrophilic and lipophilic). The use of an amphiphilic material on the surface of the isolation structure of the present application can increase the compatibility between the isolation structure 101 and the light-emitting material, thereby improving the overall performance of the light-emitting device. In some embodiments, the amphiphilic material includes an amphiphilic polyurethane material.

[0079] During the fabrication of a light-emitting device, color mixing can easily occur between different light-emitting units. For example, a small amount of green quantum dots may be mixed into a red light-emitting unit, a small amount of red quantum dots may be mixed into a green light-emitting unit, and a small amount of red and green quantum dots may be mixed into a blue light-emitting unit, thus affecting the light quality of the light-emitting device.

[0080] In the light-emitting device of the present application, the first unit 301 includes a first light-emitting material, and the second unit 302 includes a second light-emitting material. The first unit 301 includes the second light-emitting material, and the second light-emitting material accounts for ≤5% of the mass of the first unit 301. In some embodiments, the third unit includes a third light-emitting material. The first unit includes the third light-emitting material, and the third light-emitting material accounts for ≤5% of the mass of the first unit 301. In some embodiments, the second unit 302 includes the third light-emitting material, and the third light-emitting material accounts for ≤5% of the mass of the second unit 302. In some embodiments, the third unit 303 includes the second light-emitting material, and the second light-emitting material accounts for ≤5% of the mass of the third unit 303.

[0081] In some specific application examples, the first unit 301 is a blue pixel light-emitting layer, the first light-emitting material is blue quantum dots, the second unit 302 is a red pixel light-emitting layer, the second light-emitting material is red quantum dots, and the third unit 303 is a green pixel light-emitting layer, and the third light-emitting material is green quantum dots. The red pixel light-emitting layer contains green quantum dots, and the mass percentage of green quantum dots in the red pixel light-emitting layer is ≤5%, such as the mass percentage of green quantum dots in the red pixel light-emitting layer is any value among 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, or a range consisting of any two values. The green pixel light-emitting layer contains red quantum dots, and the mass percentage of red quantum dots in the green pixel light-emitting layer is ≤5%, such as the mass percentage of red quantum dots in the green pixel light-emitting layer is any value among 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, or a range consisting of any two values. The blue pixel light-emitting layer contains red quantum dots and green quantum dots, and the mass percentage of red quantum dots in the blue pixel light-emitting layer is ≤5%, such as the mass percentage of red quantum dots in the blue pixel light-emitting layer is any value among 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, or a range consisting of any two values, and the mass percentage of green quantum dots in the blue pixel light-emitting layer is ≤5%, such as the mass percentage of green quantum dots in the blue pixel light-emitting layer is any value among 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, or a range consisting of any two values. The different quantum dot materials contained in the light-emitting unit are controlled within the scope of the present application, and the spectral purity of the light-emitting device is improved. Specifically, the spectral purity test results of the light-emitting device of the present application are as follows: in the red sub-pixel EL spectrum, the green EL luminescence peak height accounts for less than 1%; in the green sub-pixel EL spectrum, the red luminescence peak height accounts for less than 3%; in the blue sub-pixel EL spectrum, the red luminescence peak height plus the green luminescence peak height accounts for less than 5%.

[0082] In the present application, the ratio (%) of the luminescent peak height of the miscellaneous peak = miscellaneous color peak height / normal color peak height*100%.

[0083] In some embodiments, the light-emitting device also includes a functional layer, which may include at least one of the following: a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, an electron blocking layer, a buffer layer, and / or any layer that realizes other desired functions, etc.

[0084] As shown in FIG1 , the light emitting device includes the following structure:

[0085] A first electrode 2 is disposed on a substrate 1 having thin film transistors (TFTs) formed thereon. The first electrode 2 is electrically connected to the TFTs. The substrate 1 is a patterned array substrate. In some embodiments, the first electrode 2 is a light-transmitting anode and may comprise a transparent oxide such as ITO, IZO, or AZO. The first electrode 2 may comprise one or more conductive layers.

[0086] When the first electrode 2 is an anode, a first functional layer 5 is provided on the first electrode 2, and the first functional layer 5 includes a hole injection layer 501 and a hole transport layer 502. The hole injection layer 501 may include poly (3,4-ethylenedioxythiophene) / polystyrene parasulfonate (PEDOT / PSS), and the hole transport layer 502 may include poly N-vinylcarbazole (PVK), poly (N, N'-bis (4-butylphenyl) -N, N'-bis (phenyl) benzidine) (poly-TPD), 4,4'-N, N'-dicarbazolyl-biphenyl (CBP), 4,4-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD) or poly (9,9'-dioctylfluorene-co-N- (4-butylphenyl) diphenylamine (TFB) and other organic materials, or the hole transport layer 502 may include NiO or Inorganic materials such as MoO3. Those skilled in the art will appreciate that a variety of methods can be used to prepare the first functional layer 5. The thickness of the hole injection layer 501 can range from tens to hundreds of nanometers, for example, 20-300 nanometers, preferably 30-150 nanometers; the thickness of the hole transport layer 502 can range from tens to hundreds of nanometers, for example, 10-200 nanometers, preferably 15-100 nanometers. The hole transport layer can have i) a single-layer structure consisting of a single layer composed of a single substance, ii) a single-layer structure consisting of multiple single layers composed of different substances, or iii) a multi-layer structure comprising multiple layers containing multiple different substances.

[0087] The light-emitting layer 3 is positioned above the first functional layer 5. The thickness of the light-emitting layer 3 is preferably greater than 10 nanometers, more preferably greater than 20 nanometers, such as 20 to 50 nanometers, or 20 to 25 nanometers. The light-emitting layer 3 may include one or more light-emitting materials. The light-emitting material may be a quantum dot, the core and / or shell of which may further include: a II-VI semiconductor compound, a III-VI semiconductor compound, a III-V semiconductor compound, a IV-VI compound, a Group IV element or compound, a Group I-III-VI semiconductor compound, or a combination thereof. In some embodiments, the second layer 3012, the second unit 302, and the third unit 303 are disposed in the same layer, and their thicknesses are substantially the same within the range of process accuracy. The first layer 3011 is positioned above the second unit 302 and the third unit 303, overlapping them. The orthographic projections of the first layer 3011, the second unit 302, and the third unit 303 on the substrate 1 coincide.

[0088] The second functional layer 6 is provided on the light-emitting layer 3, and the second functional layer 6 includes an electron transport layer, which may include 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA), bathocuproine (BCP), tris[3-(3-pyridyl)-yl]borane (3TPYMB), LiF, tris(8-hydroxyquinoline)aluminum (Alq3), tris(8-hydroxyquinoline)gallium (Gaq3), tris(8-hydroxyquinoline)indium (Inq3), di(8-hydroxyquinoline) quinolinol) zinc (Znq2), bis(2-(2-hydroxyphenyl)benzothiazole) zinc (Zn(BTZ)2), bis(10-hydroxybenzo[h]quinolinol) beryllium (BeBq2), 8-(4-(4,6-di(naphthalene-2-yl)-1,3,5-triazin-2-yl)phenyl)quinolone (ET204), 8-hydroxyquinolinolate lithium (Liq), n-type metal oxide (e.g., ZnO, HfO2, etc.), or a combination thereof, but not limited thereto. The electron transport layer may include metal oxide nanoparticles, such as zinc oxide, zinc magnesium oxide, or a combination thereof. The metal oxide nanoparticles may include Zn 1-x M xO (wherein M is Mg, Ca, Zr, W, Li, Ti, Y, Al, or a combination thereof, and 0≤x≤0.5). In the chemical formula, x may be greater than or equal to about 0.01 and less than or equal to about 0.3, for example, less than or equal to about 0.25, less than or equal to about 0.2, or less than or equal to about 0.15. The thickness of the electron transport layer may be in the range of tens to hundreds of nanometers, for example, 10-400 nanometers, preferably 20-100 nanometers. The electron transport layer may have i) a single-layer structure consisting of a single layer composed of a single substance, ii) a single-layer structure consisting of a single layer including a plurality of substances different from each other, or iii) a multilayer structure including a plurality of layers including a plurality of substances different from each other. A second electrode 4 is arranged on the second functional layer 6. The second electrode 4 is a cathode. The second electrode 4 may include Mg, Ca, Na, Ti, In, Ir, Li, Al, Ag, Zn, Pb, Ce, Ba, LiF / Al, LiO2 / Al, LiF / Ca or BaF2 / Ca, etc. In addition, an electron injection layer may also be formed between the electron transport layer and the second electrode 4.

[0089] As shown in FIG12 , the light emitting device includes the following structure:

[0090] A first electrode 2 is provided on a substrate 1 having a thin film transistor (TFT) formed thereon. The first electrode 2 is electrically connected to the TFT. The first electrode 2 is a cathode and may include Mg, Ca, Na, Ti, In, Ir, Li, Al, Ag, Zn, Pb, Ce, Ba, LiF / Al, LiO2 / Al, LiF / Ca, or BaF2 / Ca.

[0091] The first functional layer 5 includes an electron transport layer and is disposed on the first electrode 2 .

[0092] The light-emitting layer 3 is located on the first functional layer 5, the first layer 3011 and the second layer 3012 are located on the same layer, the second unit 302 and the third unit 303 are arranged in the same layer, and the second unit 302 and the third unit 303 are located on the first unit 301, and the second unit 302 and the third unit 303 are superimposed on the first unit 301, and the first layer 3011 coincides with the orthographic projections of the second unit 302 and the third unit 303 on the substrate 1.

[0093] The second functional layer 6 includes a hole transport layer and a hole injection layer. The second functional layer 6 is disposed on the light-emitting layer 3 .

[0094] The second electrode 4 is located on the first functional layer 5 and is an anode.

[0095] In some embodiments, the present application provides a method for preparing a light-emitting device, comprising the following preparation steps: providing a substrate 1;

[0096] A first electrode 2 is formed, and the first electrode 2 is located on a substrate 1; a light-emitting layer 3 is prepared, including: forming a first unit 301 and a second unit 302 arranged along a first direction X of the substrate 1, the first unit 301 is used to emit light in a first wavelength range, and the second unit 302 is used to emit light in a second wavelength range, and the first wavelength range is lower than the second wavelength range; the first unit 301 includes a first layer 3011 and a second layer 3012 arranged along the first direction X of the substrate 1, and the orthographic projection of the first layer 3011 on the substrate 1 overlaps with the orthographic projection of the second unit 302 on the substrate 1.

[0097] The second electrode 4 is formed; the first unit 301 is close to the first electrode 2 and the second electrode 4 as one of the cathodes.

[0098] In some embodiments, the preparation of the light-emitting layer 3 further includes: forming a third unit 303 arranged along the first direction X of the substrate 1, the third unit 303 is used to emit light in a third wavelength range, and the first wavelength range is lower than the third wavelength range.

[0099] In some embodiments, the first unit 301 is prepared by the following method: forming a first material layer containing a first material on the first electrode 2 to obtain the first unit 301 , wherein the obtained first unit 301 includes a first light-emitting material.

[0100] In some embodiments, the second unit 302 is prepared by the following method: forming a second material layer containing a second material on the first electrode 2, forming an exposure area and a non-exposure area of ​​the second material layer, and removing the second material in the exposure area or the second material in the non-exposure area by a second solvent to obtain the second unit 302, and the obtained second unit 302 includes a second light-emitting material.

[0101] In some embodiments, the third unit 303 is prepared by the following method: preparing a third material layer containing a third material on the first electrode 2, forming an exposure area and a non-exposure area of ​​the third material layer, and removing the third material in the exposure area or the third material in the non-exposure area by a third solvent to obtain the third unit 303, and the obtained third unit 303 includes a third light-emitting material.

[0102] In some embodiments, the first material does not contain a photosensitive material (or the content is so low that the first unit cannot be formed by photolithography), the second material contains a photosensitive material, and the third material contains a photosensitive material.

[0103] In some embodiments, the first material layer, the second material layer, or the third material layer contains a solvent that dissolves the corresponding luminescent material, and the solvent is removed after the exposure process, such as by heating and volatilization. The solvent that dissolves the luminescent material has the same polarity as the corresponding luminescent material.

[0104] In some embodiments, the mass percentage concentration of the photosensitive material is 0.01 to 2 wt% based on the total mass of the material layer (including solvent). For example, the mass percentage concentration of the photosensitive material can be any value among 0.02 wt%, 0.05 wt%, 0.06 wt%, 0.08 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt%, or a range consisting of any two values.

[0105] In some embodiments, the mass percentage concentration of the quantum dot material is 1 to 50 wt % based on the total mass of the material layer (including the solvent). For example, the mass percentage concentration of the quantum dot material is 20 to 30 wt %. For example, the mass percentage concentration of the quantum dot material can be any value of 1 wt %, 5 wt %, 10 wt %, 15 wt %, 20 wt %, 25 wt %, 30 wt %, 35 wt %, 40 wt %, 45 wt %, or 50 wt %, or a range consisting of any two values. In some embodiments, the mass fraction of the quantum dot material is 50 to 100 % based on the total mass of the light-emitting unit.

[0106] In some embodiments, the light-emitting layer 3 can be prepared using a known method such as spin coating, spray coating, casting, inkjet printing, or the Langmuir-Blodgett method. In some specific embodiments, the light-emitting layer 3 is prepared from a material dispersed with quantum dots, and the second unit 302 or the third unit 303 of the light-emitting layer is specifically prepared by photolithography. The first unit 301 of the light-emitting layer can be formed by a coating method such as spin coating or full-surface coating. Since the first unit 301 does not require photolithography and does not involve development and elution, the performance of the first unit 301 is not compromised.

[0107] In some embodiments, the first electrode 2 is an anode, the second electrode 4 is a cathode, the first functional layer 5 includes a hole injection layer and a hole transport layer, the second functional layer 6 includes an electron transport layer, and the preparation of the light-emitting layer 3 includes:

[0108] forming a second material layer containing a second material on the first functional layer 5, forming an exposed area and a non-exposed area in the second material layer, and removing the second material in the exposed area or the second material in the non-exposed area by a first solvent to obtain a second unit 302;

[0109] forming a third material layer containing a third material on the substrate having the second unit 302 formed thereon, forming an exposed area and a non-exposed area in the third material layer, and removing the third material in the exposed area or the non-exposed area by a second solvent to obtain a third unit 303;

[0110] On the substrate having the third unit 303 formed thereon, a first material layer containing a first material is formed to obtain the first unit 301 . The first material layer is not exposed or developed to directly obtain the first unit 301 .

[0111] In some embodiments, the first electrode 2 is a cathode, the second electrode 4 is an anode, the first functional layer 5 includes an electron transport layer, the second functional layer 6 includes a hole injection layer and a hole transport layer, and the preparation of the light-emitting layer 3 includes:

[0112] A first material layer containing a first material is formed on the first functional layer 5 to obtain a first unit 301. The first material layer is not exposed or developed, and the first unit 301 is directly formed.

[0113] forming a second material layer containing a second material on the first unit 301, forming an exposed area and a non-exposed area in the second material layer, and removing the second material in the exposed area or the second material in the non-exposed area by a first solvent to obtain a second unit 302;

[0114] A third material layer containing a third material is formed on the substrate formed with the second unit 302, and an exposure area and a non-exposure area are formed in the third material layer. The third material in the exposure area or the third material in the non-exposure area is removed by a second solvent to obtain a third unit 303.

[0115] In some specific embodiments, the first unit 301 is made of non-polar quantum dot material, the second unit 302 is made of polar quantum dot material, and the third unit 303 is made of polar quantum dot material; or, the first unit 301 is made of polar quantum dot material, the second unit 302 is made of non-polar quantum dot material, and the third unit 303 is made of non-polar quantum dot material; or, the first unit 301 is made of polar quantum dot material, the second unit 302 is made of non-polar quantum dot material, and the third unit 303 is made of polar quantum dot material; or, the first unit 301 is made of polar quantum dot material, the second unit 302 is made of polar quantum dot material, and the third unit 303 is made of non-polar quantum dot material; or, the first unit 301 is made of non-polar quantum dot material, the second unit 302 is made of non-polar quantum dot material, and the third unit 303 is made of polar quantum dot material; or, the first unit 301 is made of non-polar quantum dot material, the second unit 302 is made of non-polar quantum dot material, and the third unit 303 is made of polar quantum dot material; or, the first unit 301 is made of non-polar quantum dot material, the second unit 302 is made of polar quantum dot material, and the third unit 303 is made of non-polar quantum dot material.

[0116] In this application, the polarity of a substance can be characterized by its dielectric constant. When the dielectric constant ε of a substance satisfies: 0 < ε ≤ 5, the substance is a non-polar substance. When the dielectric constant ε of a substance satisfies: 5 < ε ≤ 100, the substance is a polar substance.

[0117] In some embodiments, the polarity of the quantum dot material or its solvent solubility characteristics are determined by its surface ligands. For example, the polarity of the luminescent material refers to whether the ligands on the surface of the quantum dot are polar ligands or non-polar ligands.

[0118] In some embodiments, the ligand of the quantum dot material includes at least one of a non-polar ligand or a polar ligand.

[0119] The non-polar ligand includes an alkyl carboxylic acid, an alkyl phosphonic acid, an alkyl phosphinic acid, an alkyl thiol or an alkyl amine. The alkyl group in this application includes a saturated branched alkyl group, a branched alkyl group, and an unsaturated alkyl group. In some embodiments, the alkyl group in this paragraph has 1 to 18 carbon atoms.

[0120] In certain embodiments, alkyl carboxylic acids include saturated alkyl carboxylic acids, branched alkyl carboxylic acids, and unsaturated alkyl carboxylic acids, such as oleic acid. Alkyl phosphonic acids include saturated alkyl phosphonic acids, branched alkyl phosphonic acids, and unsaturated alkyl phosphonic acids, such as octylphosphonic acid, etc. Alkyl phosphinic acids include saturated alkyl phosphinic acids, branched alkyl phosphinic acids, and unsaturated alkyl phosphinic acids, such as hexyl hypophosphorous acid, octyl hypophosphorous acid, and dodecyl hypophosphorous acid, etc. Alkyl mercaptan includes saturated alkyl mercaptan and branched alkyl mercaptan, such as 2-ethylhexyl mercaptan, octyl mercaptan, nonyl mercaptan, decyl mercaptan, undecyl mercaptan, dodecyl mercaptan, tridecyl mercaptan, tetradecyl mercaptan, hexadecyl mercaptan, or octadecyl mercaptan, etc. Alkylamines include saturated alkylamines, branched alkylamines, and unsaturated alkylamines, such as oleylamine, etc.

[0121] Polar ligands include acrylate-substituted acids, halogens, mercapto alcohols, carboxyl alcohols, or amino alcohols. Acrylate-substituted acids include acrylic acid, 2-(2-methyl-acryloyl)oxyethyl succinate, and 2-(2-acryloyloxy)hydroxyethanol succinate. Halogens include fluorine, chlorine, bromine, and iodine. Mercapto alcohols include 2-mercaptoethanol, 3-mercapto-1-propanol, 4-mercapto-1-butanol, 5-mercapto-1-pentanol, 6-mercapto-1-hexanol, and 8-mercapto-1-octanol. Carboxyl alcohols include glycolic acid, hydroxypropionic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxycaproic acid, hydroxyoctanoic acid, hydroxyheptanoic acid, hydroxybenzoic acid, hydroxyphenylacetic acid, hydroxyphenylpropionic acid, hydroxyphenylbutyric acid, hydroxyphenyl acid, hydroxyphenylcaproic acid, or hydroxyphenylalanine. Amino alcohols include ethanolamine.

[0122] In some embodiments, the ligand of the quantum dot material includes a ligand for cross-linking between quantum dot materials under light irradiation, such as mono-2-(2-methyl-acryloyl)oxyethyl succinate.

[0123] In some embodiments, the first solvent or the second solvent can be selected from the polar solvents or non-polar solvents listed in this application.

[0124] The non-polar solvent includes a hydrocarbon solvent, for example, an alkane, an alkene or an alkyne, preferably a hydrocarbon solvent having 6 to 40 carbon atoms. The alkane is a straight-chain alkane, a branched-chain alkane, a cycloalkane or an alkylbenzene, and at least one of octane, cyclohexane, tetradecane, toluene, octylbenzene and mixtures thereof can be cited.

[0125] In some embodiments, the polar solvent includes at least one of an alkyl alcohol solvent, an ether and acetal solvent, a halogenated hydrocarbon solvent, an ester solvent, and a nitrogen-containing compound solvent.

[0126] Alkyl alcohol solvents include straight-chain alkyl alcohols or branched-chain alkyl alcohols, and polyols such as methanol, ethanol, propylene glycol, and glycerol can be listed; ether and acetal solvents include alcohol ethers, such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, glycerol ether, etc.; halogenated hydrocarbon solvents include chloroform, dichloromethane, etc.; ester solvents include propylene glycol monomethyl ester, propylene glycol methyl ether acetate, ethyl acetate, ethyl benzoate, etc.; nitrogen-containing compound solvents include acetonitrile.

[0127] In some embodiments, the second material has a polarity different from the polarity of the second solvent.

[0128] In some embodiments, taking the case where the second unit 302 uses a polar quantum dot material as the second material and the third unit 303 uses a non-polar quantum dot material as the third material as an example: a second material layer containing polar quantum dots is prepared on the first functional layer 5, and a polar solvent is used as the first solvent for development to obtain the second unit 302;

[0129] A third material layer containing non-polar quantum dot material is prepared on the substrate formed with the second unit 302, and a non-polar solvent is used as the second solvent for development. Since the second unit 302 has been solidified, the polar quantum dots in the second unit 302 are still protected, reducing the performance loss of the unit during the elution process.

[0130] A first unit 301 including a non-polar quantum dot material or a polar quantum dot material is prepared on a substrate on which a third unit 303 is formed. The first unit 301 is located in a first pixel area, a second pixel area, and a third pixel area. The first unit 301 does not need to be eluted and developed, so there will be no blue light loss due to elution during the preparation process.

[0131] As shown in FIG2 to FIG6 , in some embodiments, the light emitting device is prepared by the following method:

[0132] A first functional layer 5 is formed on a substrate 1 having a first electrode 2; the first electrode 2 serves as an anode;

[0133] A second material containing polar red quantum dots is coated on the first functional layer 5. The second material contains a photosensitizer, or, if red quantum dots serve as the photosensitizer, no additional photosensitizer is required. A patterned mask is placed above the second material, and light is irradiated from above the patterned mask to expose the second material. Specifically, exposed areas are formed where the second material is located, where the patterned mask is not present, and unexposed areas are formed where the patterned mask is present.

[0134] At this point, a patterned mask is placed above the green pixel region GP and the blue pixel region BP. Therefore, light irradiating the green pixel region GP and the blue pixel region BP is blocked by the patterned mask, forming a non-exposed area. Consequently, only the second material formed on the first functional layer 5 in the red pixel region RP is exposed, forming an exposed area. The red quantum dots in the exposed area crosslink in the presence of the photosensitizer.

[0135] Next, the luminescent layer is washed with a polar first solvent as a developer, and the second material is exposed to light to obtain a negative photosensitive material that is poorly soluble in the developer. Therefore, the exposed luminescent layer does not dissolve in the developer, but remains on the first functional layer 5. As a result, the luminescent layer containing red quantum dots RQD is formed only in the red pixel region RP, forming the second unit 301.

[0136] Repeat the above steps to continue coating the third material containing non-polar green quantum dots on the substrate with the red pixel region RP, and use a non-polar third solvent as a developer to form a third unit 303 with green quantum dots GQD in the green pixel region GP.

[0137] Repeating the above steps, the first material containing blue quantum dots is further coated on the substrate formed with the red pixel region RP and the green pixel region GP. After coating, the second functional layer 6 and the second electrode 4 are formed from bottom to top on the upper layer of the light-emitting layer 3, thereby obtaining the structure shown in Figure 1. In addition, in the embodiments of the present application, the RGB three-color pattern is only an example, and other color combinations are also possible.

[0138] In some embodiments, after coating the material to prepare the light-emitting unit, a bake can be performed to remove the solvent from the material. In addition, after the light-emitting unit is developed, a post-bake can also be performed to ensure close contact between the light-emitting unit and the substrate and improve the resistance to subsequent processing.

[0139] In some embodiments, as shown in FIG9 to FIG11 , the light-emitting device is prepared by the following method:

[0140] A second functional layer 6 is formed on a substrate 1 having a first electrode 2. The first electrode 2 serves as a cathode, and a first material layer containing non-polar blue quantum dots is formed on the second functional layer 6. The first material contains a photosensitizer, which is exposed and dried to form first units 301. The first units 301 are distributed in the blue pixel region BP, the red pixel region RP, and the green pixel region GP. The first units 301 are not exposed or developed.

[0141] A second material containing polar red quantum dots is coated on a substrate containing first unit 301. A patterned mask is placed above green pixel region GP and blue pixel region BP. Therefore, light irradiating green pixel region GP and blue pixel region BP is blocked by the patterned mask, forming non-exposed areas. Consequently, only the second material formed in red pixel region RP is exposed, forming exposed areas. The quantum dot material in the exposed areas crosslinks and solidifies in the presence of a photosensitizer.

[0142] Next, the luminescent layer is washed with a polar first solvent as a developer, and the second material is exposed to light to obtain a negative photosensitive material that is poorly soluble in the developer. Therefore, the exposed second material layer does not dissolve in the developer, and thus the luminescent layer containing red quantum dots RQD is formed only in the red pixel region RP.

[0143] Repeat the above steps to continue coating the third material containing non-polar green quantum dots on the substrate formed with the red pixel area RP, and use the non-polar second solvent as the developer to form a third unit 303 with green quantum dots GQD in the green pixel area GP.

[0144] A first functional layer 5 and a second electrode 4 are formed from bottom to top on the light emitting layer 3, thereby obtaining the structure shown in Figure 12. In addition, in the embodiments of the present application, the RGB three-color pattern is only an example, and other color combinations are also possible.

[0145] In some embodiments, a light-transmitting cover layer may be formed on the second electrode 4. Optionally, an additional substrate may be provided on top of the light-emitting device to be opposite to the substrate 1 and encapsulated. By applying the above-mentioned light-emitting device to an electronic device, an electronic device with excellent light-emitting performance may be obtained. The electronic device may be a large electronic device, such as a television, a monitor, and / or an outdoor billboard. In other embodiments, the electronic device may be a small or medium-sized electronic device, such as a personal computer, a laptop computer, a personal digital terminal, a car navigation system, a game console, a smart phone, a tablet computer, and / or a camera.

[0146] In some embodiments, the non-polar quantum dot layer is prepared by the following method:

[0147] Red quantum dot layer: Set the parameters of 2000 rpm and 45 s to spin-coat the quantum dot solution on the hole transport layer. The red quantum dots are CdSe / ZnS quantum dots, the ligand is oleic acid, and the photosensitive crosslinker is (1E,4E)-1,5-bis(4-azido-2,3,5,6-tetrafluorophenyl)penta-1,4-dien-3-one. The quantum dot mass concentration is 15 mg / mL and is dissolved in n-octane solution. UV exposure is 300 mj / cm 2 After exposure, the film layer was developed using toluene. After development, it was annealed at 120° C. for 20 minutes to form a patterned red light quantum dot luminescent layer.

[0148] Green quantum dot layer: The quantum dot solution was spin-coated on the hole transport layer at 2000 rpm for 45 s. The green quantum dots were CdSe / ZnS quantum dots, the ligand was oleic acid, the photosensitive crosslinker was (1E,4E)-1,5-bis(4-azido-2,3,5,6-tetrafluorophenyl)penta-1,4-dien-3-one, the quantum dot mass concentration was 15 mg / mL, and the solution was dissolved in n-octane solution. The UV exposure was 300 mj / cm 2 After exposure, the film layer is developed with toluene, and after development, it is annealed at 120°C for 20 minutes to form a patterned green quantum dot light-emitting layer.

[0149] Blue quantum dot layer (without photosensitizer): Set the parameters of 2000 rpm and 45 s to spin-coat the quantum dot solution on the hole transport layer, where the blue quantum dots are quantum dots with a CdSe / ZnS structure, the ligand is oleic acid, and the quantum dot mass concentration is 15 mg / mL. Dry to obtain a blue light quantum dot luminescent layer.

[0150] The polar quantum dot layer was prepared by the following method:

[0151] Red quantum dot layer: Set the parameters of 2000 rpm and 45 s to spin-coat the quantum dot solution on the hole transport layer. The red quantum dots are CdSe / ZnS quantum dots, the ligand is succinic acid mono-2-(2-methyl-acryloyl)oxyethyl ester, the quantum dot mass concentration is 15 mg / mL, and the photosensitizer is ethyl 2,4,6-trimethylbenzoylphenylphosphonate, dissolved in propylene glycol monomethyl ether (PGME) solution. UV exposure is 300 mj / cm 2 After exposure, the film layer was developed using PGME, and after development, it was annealed at 120°C for 20 minutes to form a patterned red light quantum dot luminescent layer.

[0152] Green quantum dot layer: Set the parameters of 2000 rpm and 45 s to spin-coat the quantum dot solution on the hole transport layer. The green quantum dots are CdSe / ZnS quantum dots, the ligand is succinic acid mono-2-(2-methyl-acryloyl)oxyethyl ester, the quantum dot mass concentration is 15 mg / mL, and the photosensitizer is 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, dissolved in PGME solution. UV exposure is 300 mj / cm 2 After exposure, the film layer was developed using PGME, and after development, it was annealed at 120°C for 20 minutes to form a patterned green quantum dot light-emitting layer.

[0153] Blue quantum dot layer: Set the parameters of 2000 rpm and 45 s to spin-coat the quantum dot solution on the hole transport layer, where the blue quantum dots are quantum dots of CdSe / ZnS structure, the ligand is succinic acid mono-2-(2-methyl-acryloyl)oxyethyl ester, and the quantum dot mass concentration is 15 mg / mL. Dry to obtain a blue light quantum dot luminescent layer.

[0154] The following examples are all produced in the order of RGB.

[0155] Other functional layers can be prepared by the following methods:

[0156] Hole injection layer: The cleaned ITO glass sheets were spin-coated with PEDOT:PSS in air at a speed of 3500 r / min for 45 seconds. After spin coating, the sheets were annealed in air at a temperature of 150°C for 30 minutes. After annealing, the sheets were quickly transferred to a glove box with a nitrogen atmosphere.

[0157] Hole transport layer: A hole transport layer of 8 mg / mL TFB was spin-coated on the hole injection layer at a speed of 3000 r / min for 45 seconds. After spin coating, the layer was annealed in a glove box at a temperature of 150°C for 20 minutes.

[0158] Zinc oxide electron transport layer: spin-coat a solution of zinc oxide nanocrystals (30 mg / mL, ethanol) on the quantum dot layer at 3000 rpm for 30 s.

[0159] The other electrode can be fabricated as follows: The prepared sample wafer is placed in a vacuum chamber and the top electrode is evaporated. The deposition rate is controlled within the range of 0.2-0.4 Å / s for the first 10 nm, increasing to approximately 1.0-2.0 Å / s after 10 nm. The thickness of the prepared silver electrode is 100 nm.

[0160] The following describes the luminescence performance of the light-emitting device of the present application in conjunction with specific examples. For the convenience of the verification experiment, a three-primary color light-emitting device was not produced, and the film layer was prepared by spin coating. In this application, red quantum dots (CdSe / CdZnSe / ZnS), green quantum dots (CdSe / ZnSe / ZnS), and blue quantum dots are CdSe / ZnS quantum dots (CdZnSe / ZnS), ligands are oleic acid and trioctylphosphine ligands, and the photosensitizer is (1E,4E)-1,5-bis(4-azido-2,3,5,6-tetrafluorophenyl)penta-1,4-dien-3-one.

[0161] The structural formula is as follows:

[0162] QLED device preparation method:

[0163] S1. Cleaning of ITO glass

[0164] Place the ITO glass slide with the number engraved on the back into a glass dish filled with ethanol solution, scrub the ITO surface clean with a cotton swab, and then ultrasonicate with acetone, deionized water, and ethanol for 10 minutes each, then blow dry with a nitrogen gun. Finally, place the cleaned ITO glass slide in oxygen plasma and continue cleaning for 10 minutes.

[0165] S2. Preparation of hole injection layer

[0166] The cleaned ITO glass slide was spin-coated with PEDOT / PSS in air at a speed of 3000 r / min for 45 seconds. After spin coating, the slide was annealed in air at 150°C for 30 minutes. After annealing, the slide was quickly transferred to a glove box with a nitrogen atmosphere.

[0167] S3. Preparation of hole transport layer (HTL)

[0168] The wafer obtained in step S2 was further spin-coated with a hole transport layer of TFB (8-10 mg / mL, chlorobenzene solution) at a speed of 2000 r / min for 45 seconds. After spin coating, the wafer was annealed in a glove box at a temperature of 150°C for 30 minutes.

[0169] S4. Preparation of red / green quantum dot luminescent layer (QDs)

[0170] After the wafer obtained in step S3 is annealed, the quantum dot solution is spin-coated. The optical density (OD) of the quantum dot solution at 350 nm is 30-40, and the solvent is n-octane. The spin-coating speed is 2000 r / min and the spin-coating time is 45 seconds. After the spin-coating is completed, the next layer can be spin-coated without annealing.

[0171] S5. Preparation of blue quantum dot luminescent layer (QDs)

[0172] After the wafer obtained in step S4 is annealed, the quantum dot solution is spin-coated. The optical density (OD) of the quantum dot solution at 350 nm is 30-40, and the solvent is n-octane. The spin-coating speed is 2000 r / min and the spin-coating time is 45 seconds. After the spin-coating is completed, the next layer can be spin-coated without annealing.

[0173] S6. Preparation of Electron Transport Layer

[0174] The wafer obtained in step S5 was spin-coated with a zinc oxide nanocrystal solution (30 mg / mL, ethanol solvent) at a speed of 2000 r / min for 45 seconds, and then the wafer was allowed to stand in air with a humidity of 60% for 30 minutes;

[0175] S7. Electrode Preparation

[0176] The wafer obtained in step S6 is placed in a vacuum chamber and the top electrode is evaporated. The evaporation rate is controlled within the range of 0.2-0.4 Å / s for the first 10 nm and is increased to about 1-2 Å / s after 10 nm. The thickness of the silver electrode is 100 nm.

[0177] Figures 13 and 14 are the electroluminescence spectra of QLEDs superimposed with a blue quantum dot layer (QD2) and a red quantum dot layer (QD1). The vertical axis is the electroluminescence intensity, and the EL spectrum data is the test results at 5V.

[0178] Figure 13 shows the test results for the following QLED structure: ITO / PEDOT:PSS (40nm thickness) / TFB (25nm thickness) / QD1 (20nm thickness) / QD2 (20nm thickness) / ZnO (40nm thickness) / Ag electrode (100nm thickness) were spin-coated sequentially. The Ag electrode serves as a reflective electrode.

[0179] Figure 14 shows the test results for the following QLED structure: ITO / PEDOT:PSS (40nm thickness) / TFB (25nm thickness) / QD2 (20nm thickness) / QD1 (20nm thickness) / ZnO (40nm thickness) / Ag electrode (100nm thickness) were spin-coated sequentially. The Ag electrode serves as a reflective electrode.

[0180] Figures 15 and 16 are the electroluminescence spectra of QLEDs superimposed with a blue quantum dot layer (QD2) and a green quantum dot layer (QD3). The vertical axis is the electroluminescence intensity, and the EL spectrum data is the test results at 5V.

[0181] Figure 15 shows the test results for the following QLED structure: ITO / PEDOT:PSS (40nm thickness) / TFB (25nm thickness) / QD3 (20nm thickness) / QD2 (20nm thickness) / ZnO (40nm thickness) / Ag electrode (100nm thickness) were spin-coated sequentially. The Ag electrode serves as a reflective electrode.

[0182] Figure 16 shows the test results for the following QLED structure: ITO / PEDOT:PSS (40nm thickness) / TFB (25nm thickness) / QD2 (20nm thickness) / QD3 (20nm thickness) / ZnO (40nm thickness) / Ag electrode (100nm) were spin-coated in this order. The Ag electrode serves as a reflective electrode.

[0183] Figures 17 and 18 are the electroluminescence spectra of QLEDs superimposed with a red quantum dot layer (QD1) and a green quantum dot layer (QD3). The vertical axis is the electroluminescence intensity, and the EL spectrum data is the test results at 5V.

[0184] Figure 17 shows the test results for the following QLED structure: ITO / PEDOT:PSS (40nm thickness) / TFB (25nm thickness) / QD1 (20nm thickness) / QD3 (20nm thickness) / ZnO (40nm thickness) / Ag electrode (100nm thickness) were spin-coated sequentially. The Ag electrode serves as a reflective electrode.

[0185] Figure 18 shows the test results for the following QLED structure: ITO / PEDOT:PSS (40nm thickness) / TFB (25nm thickness) / QD3 (20nm thickness) / QD1 (20nm thickness) / ZnO (40nm thickness) / Ag electrode (100nm thickness) were spin-coated sequentially. The Ag electrode serves as a reflective electrode.

[0186] According to the external quantum efficiency test, the external quantum efficiency of QD2 (blue quantum dot layer) is 12%. It can be seen from the results of Figures 13 to 18 that when the quantum dot layer emitting short-wavelengths is superimposed on the quantum dot layer emitting long-wavelengths, but the quantum dot layer emitting short-wavelengths is close to the electron transport layer (ETL) side, the EL spectrum is a pure long-wave emission spectrum, and when the quantum dot layer emitting long-wavelengths is close to the ETL side, the EL is a mixed spectrum. The present application superimposes the first unit 301 as a short-wavelength and the second unit 302 as a long-wavelength, so that the first unit 301 is close to the ETL side, and the first unit 301 does not require photolithography. In a specific application, the first unit 301 is a light-emitting unit that emits blue light. During the preparation process, there is no photosensitive material in the blue quantum dot material, and no development and elution are required, which reduces the impact of the development and elution process on the device performance, especially the blue light part.

[0187] The above is a detailed introduction to a light-emitting device, preparation method and electronic device provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for technical personnel in this field, based on the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A light emitting device, characterized in that: include: base(1); A first electrode (2), a light-emitting layer (3) and a second electrode (4), wherein the first electrode (2) is located on the substrate (1), and the light-emitting layer (3) is located between the first electrode (1) and the second electrode (4); The light-emitting layer (3) comprises a first unit (301) and a second unit (302) arranged along a first direction (X) of the substrate (1); the first unit (301) is used to emit light in a first wavelength range, and the second unit (302) is used to emit light in a second wavelength range, and the first wavelength range is lower than the second wavelength range; The first unit (301) comprises a first layer (3011) and a second layer (3012) arranged along a first direction (X) of the substrate (1), the orthographic projection of the first layer (3011) on the substrate (1) overlaps with the orthographic projection of the second unit (302) on the substrate (1), and the first unit (301) is closer to one of the first electrode (2) and the second electrode (4) as a cathode than the second unit (302).

2. The light emitting device according to claim 1, characterized in that: The first layer (3011) is closer to the first electrode (102) and the second electrode (104) as one of the cathodes than the second unit (302).

3. The light emitting device according to claim 1, characterized in that: The light-emitting layer (3) comprises a third unit (303) arranged along a first direction (X) of the substrate (1), and the third unit (303) is used to emit light in a third wavelength range, wherein the first wavelength range is lower than the third wavelength range.

4. The light emitting device according to claim 3, characterized in that: The orthographic projection of the first layer (3011) on the substrate (1) overlaps with the orthographic projection of the third unit (303) on the substrate (1).

5. The light emitting device according to claim 4, characterized in that: The first layer (3011) is closer to the first electrode (102) and the second electrode (104) as one of the cathodes than the third unit (303).

6. The light emitting device according to claim 1, characterized in that: It comprises a plurality of isolation structures (101), wherein the isolation structures (101) are located on the substrate (1), and the light-emitting layer (3) is divided into a plurality of light-emitting units by the isolation structures (101).

7. The light emitting device according to claim 6, characterized in that: The height of the isolation structure (101) is not lower than the height of the second unit (302).

8. The light emitting device according to claim 1, characterized in that: The invention comprises a first functional layer (5), wherein the first functional layer (5) is located between the first electrode (2) and the light-emitting layer (3), and the first functional layer (5) comprises at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, an electron blocking layer, and a buffer layer.

9. The light emitting device according to claim 1, characterized in that: The invention comprises a second functional layer (6), wherein the second functional layer (6) is located between the light-emitting layer (3) and the second electrode (4), and the second functional layer (6) comprises at least one of a hole injection layer, a hole transport layer, a hole blocking layer, an electron injection layer, an electron transport layer, an electron blocking layer, and a buffer layer.

10. The light emitting device according to claim 6, characterized in that: The isolation structure (101) has a first surface (110), and the material of the first surface (110) is amphiphilic.

11. The light emitting device according to claim 3, characterized in that: The first unit (301) includes a first luminescent material, and the second unit (302) includes a second luminescent material; the first unit (301) contains the second luminescent material, and based on the mass of the first unit (301), the mass percentage of the second luminescent material in the first unit (301) is ≤5%.

12. The light emitting device according to claim 3, characterized in that: The third unit (303) includes a third luminescent material. The first unit (301) includes a third luminescent material. Based on the mass of the first unit (301), the mass percentage of the third luminescent material in the first unit (301) is ≤5%.

13. The light emitting device according to claim 12, characterized in that: The second unit (302) includes a third luminescent material. Based on the mass of the second unit (302), the mass percentage of the third luminescent material in the second unit (302) is ≤5%.

14. The light emitting device according to claim 12, characterized in that: The third unit (303) includes a second luminescent material, and based on the mass of the third unit (303), the mass percentage of the second luminescent material in the third unit (303) is ≤5%.

15. A method for preparing a light emitting device, characterized in that: The method comprises the following preparation steps: Providing a substrate (1); forming a first electrode (2), wherein the first electrode (2) is located on the substrate (1); A light-emitting layer (3) is formed, wherein the light-emitting layer (3) is located on the first electrode (2), and the preparation of the light-emitting layer (3) comprises: A first unit (301) and a second unit (302) are formed along a first direction (X) of the substrate (1), wherein the first unit (301) is used to emit light in a first wavelength range, and the second unit (302) is used to emit light in a second wavelength range, wherein the first wavelength range is lower than the second wavelength range; the first unit (301) includes a first unit (301) and a second unit (302) arranged along the first direction (X) of the substrate (1); A first layer (3011) and a second layer (3012) are arranged in a first direction (X) of the substrate (1), wherein an orthographic projection of the first layer (3011) on the substrate (1) overlaps with an orthographic projection of the second unit (302) on the substrate (1); forming a second electrode (4), wherein the second electrode (4) is located on the light-emitting layer (3); The first unit (301) is closer to one of the first electrode (2) and the second electrode (4) as a cathode than the second unit (302).

16. The method for preparing a light emitting device according to claim 15, characterized in that: The preparation of the second unit (302) includes: forming a second material layer containing a second material on the first electrode (2), forming an exposure area and a non-exposure area on the second material layer, and removing the second material in the exposure area or the second material in the non-exposure area by a first solvent to obtain a second unit (302); The preparation of the first unit (301) comprises: forming a first material layer containing a first material on the first electrode (2) to obtain the first unit (301).

17. The method for preparing a light emitting device according to claim 16, characterized in that: The preparation of the light-emitting layer (3) comprises: forming a third unit (303) arranged along a first direction (X) of the substrate (1), wherein the third unit (303) is used to emit light in a third wavelength range, wherein the first wavelength range is lower than the third wavelength range.

18. The method for preparing a light emitting device according to claim 17, characterized in that: The preparation of the third unit (303) includes: forming a third material layer containing a third material on the first electrode (2), forming an exposure area and a non-exposure area on the third material layer, and removing the third material in the exposure area or the third material in the non-exposure area by a second solvent to obtain the third unit (303).

19. The method for preparing a light emitting device according to claim 18, characterized in that: The third solvent has a polarity different from that of the second material.

20. An electronic device, characterized in that: A light-emitting device comprising the light-emitting device according to any one of claims 1 to 14, or a light-emitting device obtained by the method for preparing the light-emitting device according to any one of claims 15 to 19.

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