Optoelectronic device and method of manufacturing the same

Abstract

This application discloses an optoelectronic device and its fabrication method. The optoelectronic device includes an anode, a light-emitting layer, and a cathode stacked sequentially. The light-emitting layer includes a first quantum dot layer and a second quantum dot layer stacked together. The first quantum dot layer is located between the anode and the second quantum dot layer. The material of the first quantum dot layer includes a first quantum dot and a first ligand, wherein the first ligand is a compound containing a thiol group. The material of the second quantum dot layer includes a second quantum dot and a second ligand, wherein the second ligand is a halide. The optoelectronic device of this application has high brightness.

Description

Technical Field

[0001] This application relates to the field of display technology, and in particular to an optoelectronic device and its fabrication method. Background Technology

[0002] Currently, the most widely used optoelectronic devices are organic light-emitting diodes (OLEDs) and quantum dot LEDs. OLEDs, due to their superior display performance, including self-illumination, simple structure, ultra-thinness, fast response time, wide viewing angle, low power consumption, and flexible display capabilities, have become the mainstream technology in the display field. QLEDs offer advantages such as saturated emitted light color, tunable wavelength, low turn-on voltage, good solution processability, and easy fine control of quantum dots. Furthermore, they boast high quantum yields in both photoluminescence and electroluminescence, making them a strong competitor to OLEDs in recent years.

[0003] Traditional OLED and QLED device structures generally include an anode, a hole injection layer, a hole transport layer, a photoelectric functional layer, an electron transport layer, an electron injection layer, and a cathode. Under the influence of an electric field, holes generated at the anode and electrons generated at the cathode move and are injected into the hole transport layer and electron transport layer, respectively, eventually migrating to the photoelectric functional layer. When the two meet in the photoelectric functional layer, they generate excitons, which in turn excite the light-emitting molecules to produce visible light.

[0004] However, the brightness of existing optoelectronic devices is relatively low and needs to be further improved. Summary of the Invention

[0005] In view of this, this application provides an optoelectronic device and a method for fabricating the same.

[0006] This application also provides an optoelectronic device, including an anode, a light-emitting layer, and a cathode stacked sequentially. The light-emitting layer includes a first quantum dot layer and a second quantum dot layer stacked together. The first quantum dot layer is located between the anode and the second quantum dot layer. The material of the first quantum dot layer includes a first quantum dot and a first ligand, wherein the first ligand is a compound containing a thiol group. The material of the second quantum dot layer includes a second quantum dot and a second ligand, wherein the second ligand is a halide.

[0007] Accordingly, embodiments of this application also provide a method for fabricating an optoelectronic device, comprising the following steps:

[0008] Provide the first electrode;

[0009] A light-emitting layer is prepared on the first electrode;

[0010] A second electrode is fabricated on the light-emitting layer to obtain a photoelectric device;

[0011] Wherein, the first electrode is the anode, the second electrode is the cathode, and the step of fabricating a light-emitting layer on the first electrode includes:

[0012] A first quantum dot is deposited on the first electrode to obtain a first quantum dot film, wherein an oil-soluble organic ligand is attached to the surface of the first quantum dot; a solution of a thiol-containing compound is provided, the thiol-containing compound solution comprising a thiol-containing compound and a first solvent, the thiol-containing compound solution is disposed on the first quantum dot film, and a first heating is performed to form a first quantum dot layer; and

[0013] A second quantum dot is deposited on the first quantum dot layer to obtain a second quantum dot film, wherein the surface of the second quantum dot is connected with an oil-soluble organic ligand; a halide solution is provided, the halide solution including a halide and a second solvent, the halide solution is placed on the second quantum dot film, and then heated to form a second quantum dot layer, thereby obtaining a light-emitting layer;

[0014] or,

[0015] Wherein, the first electrode is a cathode, the second electrode is an anode, and the fabrication of the light-emitting layer on the first electrode includes:

[0016] A second quantum dot is deposited on the first electrode to obtain a second quantum dot film, wherein the surface of the second quantum dot is connected with an oil-soluble organic ligand; a halide solution is provided, the halide solution comprising a halide and a second solvent, the halide solution is disposed on the second quantum dot film, and then heated to form a second quantum dot layer; and

[0017] A first quantum dot is deposited on the second quantum dot layer to obtain a first quantum dot film, wherein an oil-soluble organic ligand is attached to the surface of the first quantum dot; a solution of a thiol-containing compound is provided, the solution of the thiol-containing compound comprising a thiol-containing compound and a first solvent, the thiol-containing compound solution is placed on the first quantum dot film, and a first heating is performed to form a first quantum dot layer, thereby obtaining a light-emitting layer.

[0018] The optoelectronic device described in this application has high brightness. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1This is a schematic diagram of the structure of an optoelectronic device provided in an embodiment of this application;

[0021] Figure 2 This is a schematic diagram of another optoelectronic device provided in an embodiment of this application;

[0022] Figure 3 This is a flowchart of a method for fabricating an optoelectronic device provided in an embodiment of this application.

[0023] Figure label:

[0024] Optoelectronic device 100; anode 10; light-emitting layer 20; first quantum dot layer 21; second quantum dot layer 22; cathode 30; electron transport layer 40; hole transport layer 50; hole injection layer 60. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Furthermore, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application.

[0026] In this application, unless otherwise stated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of the device in its actual use or operating state, specifically the drawing directions in the accompanying drawings; while "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative purposes and do not impose numerical requirements or establish a numerical order.

[0027] In this application, "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0028] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c," or "at least one of a, b, and c," can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0029] In this application, the term "on" forming another layer on a certain layer is a broad concept. It can mean that the formed other layer is adjacent to a certain layer, or it can mean that there are other spacer structures between the other layer and the certain layer. For example, when a second electrode is formed "on" a first charge carrier functional layer, the term "on" can mean that the formed second electrode is adjacent to the first charge carrier functional layer, or it can mean that there are other spacer structures between the second electrode and the first charge carrier functional layer, such as a light-emitting layer.

[0030] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0031] In this application, the thickness of the film was measured using a step tester, and the particle size was measured using a transmission electron microscope (TEM).

[0032] Quantum dot films are functional films commonly used in optoelectronic devices. Quantum dots prepared by solution methods typically have long-chain organic ligands on their surface, such as trioctylphosphine oxide (TOPO) and oleic acid (OA). During operation, these long-chain ligands act as barriers to charge transfer. Furthermore, due to the deep band structure of blue quantum dots, the presence of long-chain ligands makes electron injection easier but hole injection more difficult, hindering hole injection and consequently affecting the efficiency and lifetime of optoelectronic devices.

[0033] Existing technologies involve adding inorganic compounds, such as halides, to quantum dot solutions for ligand exchange, replacing long-chain ligands with halides. However, on the one hand, halides may over-replace long-chain ligands, causing quantum dots in the solution to easily aggregate and settle. On the other hand, electron-withdrawing groups such as halogens, when used as ligands, can lower the energy levels of quantum dots, resulting in a deeper valence band and making it more difficult for holes to be injected.

[0034] The technical solution of this application is as follows:

[0035] Please see Figure 1This application provides an optoelectronic device 100, which includes an anode 10, a light-emitting layer 20 and a cathode 30 stacked sequentially. The light-emitting layer 20 includes a first quantum dot layer 21 and a second quantum dot layer 22 stacked together. The first quantum dot layer 21 is located between the anode 10 and the second quantum dot layer 22.

[0036] The material of the first quantum dot layer 21 includes a first quantum dot and a first ligand, wherein the first ligand is a compound containing a thiol group.

[0037] The material of the second quantum dot layer 22 includes a second quantum dot and a second ligand, wherein the second ligand is a halide.

[0038] It can be understood that the first ligand is coordinated with the first quantum dot, and the second ligand is coordinated with the second quantum dot. In other words, the first ligand is coordinated with the surface of the first quantum dot, and the second ligand is coordinated with the surface of the second quantum dot.

[0039] In the optoelectronic device 100 described in this application, the surface of the first quantum dot in the first quantum dot layer 21 near the anode 10 of the light-emitting layer 20 is connected to a thiol-containing compound as a first ligand. The thiol group in the thiol-containing compound is an electron-donating group, which can effectively increase the energy level of the first quantum dot and facilitate hole injection. The surface of the second quantum dot in the second quantum dot layer 22 near the cathode 30 of the light-emitting layer 20 is connected to a halide as a second ligand, which can effectively improve the electron transport of the second quantum dot. Thus, the number of holes and electrons injected into the light-emitting layer 20 can be increased, which is beneficial to improving the hole injection efficiency and electron injection efficiency. It can also effectively improve the conductivity of the light-emitting layer 20, thereby effectively improving the brightness and lifespan of the optoelectronic device 100.

[0040] In some embodiments, the mass ratio of the first quantum dot to the first ligand in the first quantum dot layer 21 ranges from (8-9):(1-2), for example, 8:1, 8:1.1, 8:1.2, 8:1.3, 8:1.4, 8:1.5, 8:1.6, 8:1.7, 8:1.8, 8:1.9, 8:2, 9:1, 9:1.1, 9:1.2, 9:1.3, 9:1.4, 9:1.5, 9:1.6, 9:1.7, 9:1.8, 9:1.9, and 9:2. Within this range, a higher content of the first ligand can effectively increase the energy level of the first quantum dot, which is beneficial for hole injection.

[0041] The mass ratio of the second quantum dot to the second ligand in the second quantum dot layer 22 ranges from (8-9):(1-2), for example, 8:1, 8:1.1, 8:1.2, 8:1.3, 8:1.4, 8:1.5, 8:1.6, 8:1.7, 8:1.8, 8:1.9, 8:2, 9:1, 9:1.1, 9:1.2, 9:1.3, 9:1.4, 9:1.5, 9:1.6, 9:1.7, 9:1.8, 9:1.9, and 9:2. Within this range, the content of the second ligand is relatively high, which can effectively improve the charge transport of the second quantum dot.

[0042] In some embodiments, the thiol-containing compounds include, but are not limited to, one or more of saturated aliphatic thiols with 1 to 8 carbon atoms in the main chain, unsaturated aliphatic thiols with 2 to 8 carbon atoms in the main chain, and alicyclic thiols with 3 to 8 ring atoms.

[0043] In some embodiments, the saturated aliphatic thiols with a main chain of 1 to 8 carbon atoms include one or more of mono-saturated aliphatic thiols with a main chain of 1 to 8 carbon atoms and poly-saturated aliphatic thiols with a main chain of 2 to 8 carbon atoms.

[0044] In some embodiments, the unsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms include one or more of monounsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms and polyunsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms.

[0045] It is understood that the monobasic saturated aliphatic thiol refers to a saturated aliphatic thiol containing only one -SH group, while the polybasic saturated aliphatic thiol refers to a saturated aliphatic thiol containing two or more -SH groups.

[0046] In some instances, the monobasic saturated aliphatic thiols with 1 to 8 carbon atoms in the main chain include, but are not limited to, one or more of the following: methanethiol, ethanethiol, n-propanethiol, isopropanethiol, n-butanethiol, isobutanethiol, sec-butanethiol, 2-methyl-1-butanethiol, 3-methyl-2-butanethiol, tert-butanethiol, 1-pentanethiol, 2-pentanethiol, isopentanethiol, 1-hexanethiol, 1-heptanethiol, 1-octanethiol, sec-octanethiol, isooctanethiol, tert-nonylthiol, and cyclopropylmethanethiol.

[0047] In some instances, the polybasic saturated aliphatic thiols having 2 to 8 carbon atoms in their main chain include, but are not limited to, one or more of 1,2-ethanedithiol, 1,3-propanedithiol, 2,3-butanedithiol, 1,2-butanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, and 1,8-octanedithiol.

[0048] In some instances, the unsaturated aliphatic thiols having 2 to 8 carbon atoms in their main chain include, but are not limited to, allyl thiols, allyl butyl thiols, allyl pentyl thiols, 3-methyl-2-buten-1-thiols, 3,7-dimethyl-2,6-octadien-1-thiols, and prop-2-yn-1-thiols.

[0049] The alicyclic thiols having 3 to 8 ring atoms include, but are not limited to, one or more of cyclopropanethiol, cyclopentanethiol, cyclohexanethiol, cycloheptanethiol, and cyclooctanethiol.

[0050] In some embodiments, the halides include, but are not limited to, one or more of zinc halides, magnesium halides, ammonium halides, thionyl halides, phosphorus trihalides, and phosphorus trihalomethanes. The zinc halides include, but are not limited to, one or more of ZnCl2, ZnBr2, and ZnI2; the magnesium halides include, but are not limited to, one or more of MgCl2, MgBr2, and MgI2; the ammonium halides include, but are not limited to, one or more of NH4Cl, NH4Br, and NH4I2; the thionyl halides include, but are not limited to, one or more of thionyl chloride (SOCl2) and thionyl bromide (SOBr2); the phosphorus trihalides include, but are not limited to, one or more of phosphorus trichloride and phosphorus tribromide; and the phosphorus trihalomethanes include, but are not limited to, one or more of phosphorus oxychloride and phosphorus tribromide.

[0051] In some embodiments, the surface of the first quantum dots in the first quantum dot layer 21 is not connected to oil-soluble organic ligands. In other embodiments, the surface of the first quantum dots in the first quantum dot layer 21 is also coordinated with oil-soluble organic ligands, the content of which is less than or equal to 12 wt%. In the light-emitting layer 20 of this application, the surface of the first quantum dot layer 21 near the anode 10 is not connected to oil-soluble organic ligands or the content of oil-soluble organic ligands is very low. This effectively reduces or even avoids the obstruction of charge transfer by oil-soluble organic ligands, effectively improving hole injection, thereby enabling the optoelectronic device 100 of this application to have higher brightness and longer lifespan.

[0052] In some embodiments, the surface of the second quantum dots in the second quantum dot layer 22 is not connected to oil-soluble organic ligands. In other embodiments, the surface of the second quantum dots in the second quantum dot layer 22 is also coordinated with oil-soluble organic ligands, the content of which is less than or equal to 12 wt%. In the light-emitting layer 20 of this application, the surface of the second quantum dots in the second quantum dot layer 22 near the cathode 30 is not connected to oil-soluble organic ligands or has a low content of oil-soluble organic ligands. This effectively reduces or even avoids the obstruction of charge transfer by oil-soluble organic ligands, effectively improving charge transport, thereby enabling the optoelectronic device 100 of this application to have higher brightness and longer lifespan.

[0053] The oil-soluble organic ligands include, but are not limited to, substituted or unsubstituted C6-C ligands. 24 Fatty acids, substituted or unsubstituted C6-C 24 Fatty amines, substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides, substituted or unsubstituted C8-C8 phosphine oxides 20 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphorous acid and substituted or unsubstituted C6-C 24 At least one of the fatty phosphites, wherein the substituent is selected from at least one of C1-C6 alkyl, C1-C6 alkoxy and halogen.

[0054] In some embodiments, the substituted or unsubstituted C6-C 24 Fatty acids include at least one of the following: decanoic acid, undecenoic acid, tetradecanoic acid, oleic acid (OA), linoleic acid, and stearic acid.

[0055] In some embodiments, the substituted or unsubstituted C6-C 24 Fatty amines include at least one of oleylamine, octadecylamine, octylamine, dioctylamine, and trioctylamine.

[0056] In some embodiments, the substituted or unsubstituted C6-C 24 Aliphatic phosphines include trioctylphosphine.

[0057] In some embodiments, the substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides include tri-n-octylphosphine oxide (TOPO).

[0058] In some embodiments, the average thickness of the first quantum dot layer 21 and the second quantum dot layer 22 is independently 15 to 25 nm, for example, 15 nm, 16 nm, 18 nm, 20 nm, 22 nm, 23 nm, 25 nm, and any range between two values.

[0059] In some embodiments, the average particle size of the first quantum dot and the second quantum dot is independently 11 to 13 nm, for example, 11 nm, 11.5 nm, 12 nm, 12.5 nm, 13 nm, and any range between two values.

[0060] The first quantum dot and the second quantum dot are each independently one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite quantum dots. The core-shell structure quantum dot comprises one or more shell layers.

[0061] The materials for the single-structure quantum dots, the core materials for the core-shell structure quantum dots, and the shell materials for the core-shell structure quantum dots may include, but are not limited to, one or more of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds. The group II-VI compounds may include, but are not limited to, one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe. The IV-VI group compounds may include, but are not limited to, one or more of SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, and SnPbSTe. The group III-V compounds may include, but are not limited to, one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, GaAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb. The group I-III-VI compounds may include, but are not limited to, one or more of CuInS2, CuInSe2, and AgInS2.

[0062] As an example, the core-shell structured quantum dots may include, but are not limited to, one or more of CdSe / CdSeS / CdS, InP / ZnSeS / ZnS, CdZnSe / ZnSe / ZnS, CdSeS / ZnSeS / ZnS, CdSe / ZnS, CdSe / ZnSe / ZnS, ZnSe / ZnS, ZnSeTe / ZnS, CdSe / CdZnSeS / ZnS, and InP / ZnSe / ZnS.

[0063] The perovskite quantum dots may include, but are not limited to, doped or undoped inorganic perovskite quantum dots, or organic-inorganic hybrid perovskite quantum dots. The general structural formula of the inorganic perovskite quantum dots is AMX3, where A is Cs. + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following. The general structural formula of the organic-inorganic hybrid perovskite quantum dots is BMX3, where B is an organic amine cation, including CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2 + Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of them.

[0064] Please see Figure 2 In some embodiments, the optoelectronic device 100 further includes an electron transport layer 40 located between the light-emitting layer 20 and the cathode 30.

[0065] In some embodiments, the optoelectronic device 100 further includes a hole transport layer 50, which is located between the light-emitting layer 20 and the anode 10.

[0066] In some embodiments, the optoelectronic device 100 further includes a hole injection layer 60, which is located between the light-emitting layer 20 and the hole transport layer 50.

[0067] The anode 10 and the cathode 30 are anodes and cathodes known in the art for use in optoelectronic devices. For example, they can be independently selected from, but not limited to, doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The material of the doped metal oxide electrode can be selected from, but not limited to, at least one of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), and aluminum-doped magnesium oxide (AMO). The composite electrode is a composite electrode in which a metal is sandwiched between doped or undoped transparent metal oxides, such as AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, etc. The material of the elemental metal electrode can be selected from, but is not limited to, at least one of Ag, Al, M, Au, Pt, Ca, and Ba. Here, " / " indicates a stacked structure; for example, AZO / Ag / AZO represents a composite electrode comprising sequentially stacked AZO, Ag, and AZO layers.

[0068] The material of the electron transport layer 40 includes, but is not limited to, one or more of N-type inorganic particles and N-type organic materials. The materials of the N-type inorganic particles include, but are not limited to, one or more of the following: first doped metal oxide particles, first undoped metal oxide particles, IIB-VIA group semiconductor materials, IIIA-VA group semiconductor materials, and IB-IIIA-VIA group semiconductor materials. The materials of the first undoped metal oxide particles include, but are not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxides in the first doped metal oxide particles include, but are not limited to, one or more of ZnO, TiO2, SnO2, ZrO2, Ta2O5, and Al2O3. The doping elements in the first doped metal oxide particles include, but are not limited to, one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga. The IIB-VIA group semiconductor materials include, but are not limited to, one or more of ZnS, ZnSe, and CdS. The IIIA-VA group semiconductor materials include, but are not limited to, one or more of InP and GaP. The IB-IIIA-VIA group semiconductor materials include, but are not limited to, one or more of CuInS and CuGaS. The N-type organic materials include, but are not limited to, one or more of the following: quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds, and fullerene derivatives (PCBM).

[0069] The materials of the hole transport layer 50 and the hole injection layer 60 are each independently including, but not limited to, one or more of P-type inorganic particles and P-type organic materials. The P-type inorganic particles include, but are not limited to, one or more of second-doped metal oxide particles, second-undoped metal oxide particles, metal sulfides, metal selenides, and metal nitrides. The metal oxides in the second-doped metal oxide particles and the metal oxides in the second-undoped metal oxide particles are each independently including, but not limited to, one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, and V2O5. The doping elements in the second-doped metal oxide particles include, but are not limited to, one or more of Mo, W, Ni, Cr, Cu, and V. The metal sulfides include, but are not limited to, one or more of CuS, MoS3, and WS3. The metal selenides include, but are not limited to, one or more of MoSe3 and WSe3. The metal nitrides include, but are not limited to, P-type gallium nitride. The p-type organic semiconductor material can be selected from, but is not limited to, 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NPD), and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4’-diamine (T... PD), poly(N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (Poly-TPD), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)-spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4',4'-tris(N-carbazolyl)-triphenylamine (TCTA), 4,4',4'-tris( N-3-Methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4-4'-diamine (NPB), spiroNPB, poly(phenylene vinylene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene](MOMO-PPV), 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene (spiro-omeTAD), 4,4'-cyclohexyldi[N,[N-Di(4-methylphenyl)aniline] (TAPC), 1,3-Di(carbazole-9-yl)phenyl (MCP), polyaniline, polypyrrole, poly(p-)phenylenevinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazole)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylates and their derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, 2,3,6,7, One or more of the following: 10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene (HAT-CN), PEDOT, PEDOT:PSS, PEDOT:PSS-doped s-MoO3 derivatives (PEDOT:PSS:s-MoO3), 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA), tetracyanoquinone dimethylane (F4-TCQN), doped graphene, undoped graphene, C60, and copper phthalocyanine.

[0070] It is understood that the optoelectronic device 100 may also be provided with some functional layers that help improve the performance of the optoelectronic device, such as an electron injection layer, an electron blocking layer, a hole blocking layer, an interface modification layer, etc.

[0071] It is understood that the materials of each layer of the optoelectronic device 100 can be adjusted according to the light emission requirements of the optoelectronic device 100.

[0072] It is understood that the optoelectronic device 100 can be an upright optoelectronic device or an inverted optoelectronic device.

[0073] In some embodiments, the optoelectronic device 100 further includes a substrate located on the surface of the anode 10 away from the light-emitting layer 20, or the substrate located on the surface of the cathode 30 away from the light-emitting layer 20.

[0074] The substrate can be a rigid substrate or a flexible substrate. In some embodiments, the substrate material may include, but is not limited to, one or more of glass, silicon wafer, polycarbonate, polymethyl methacrylate, polyethylene terephthalate, polyethylene naphthalate, polyamide, and polyethersulfone.

[0075] It is understood that the optoelectronic device 100 can be an upright optoelectronic device or an inverted optoelectronic device. The optoelectronic device 100 can be a quantum dot optoelectronic device or an organic optoelectronic device.

[0076] Secondly, please refer to Figure 3 This application also provides a method for fabricating an optoelectronic device 100, comprising the following steps:

[0077] Step S11: Provide the first electrode;

[0078] Step S12: Prepare a light-emitting layer 20 on the first electrode;

[0079] Step S13: A second electrode is prepared on the light-emitting layer 20 to obtain the optoelectronic device 100.

[0080] In some embodiments, the first electrode is an anode 10, the second electrode is a cathode 30, and the fabrication of the light-emitting layer 20 on the first electrode includes:

[0081] Step A1: Deposit a first quantum dot on the first electrode to obtain a first quantum dot film, wherein an oil-soluble organic ligand is attached to the surface of the first quantum dot; provide a solution of a thiol-containing compound, the solution of which includes a thiol-containing compound and a first solvent; place the solution of the thiol-containing compound on the first quantum dot film; perform ligand exchange, so that the thiol-containing compound replaces the oil-soluble organic ligand on the surface of the first quantum dot; perform a first heating to form a first quantum dot layer 21;

[0082] Step A2: Deposit a second quantum dot on the first quantum dot layer to obtain a second quantum dot film, wherein the surface of the second quantum dot is connected with an oil-soluble organic ligand; provide a halide solution, the halide solution including a halide and a second solvent, place the halide solution on the second quantum dot film, perform ligand exchange, so that the halide replaces the oil-soluble organic ligand on the surface of the second quantum dot, and then heat to form a second quantum dot layer 22, thereby obtaining a light-emitting layer 20.

[0083] In other embodiments, the first electrode is a cathode 30, the second electrode is an anode 10, and the fabrication of the light-emitting layer 20 on the first electrode includes:

[0084] Step B1: Deposit a second quantum dot on the first electrode to obtain a second quantum dot film, wherein the surface of the second quantum dot is connected with an oil-soluble organic ligand; provide a halide solution, the halide solution including a halide and a second solvent, place the halide solution on the second quantum dot film, perform ligand exchange, so that the halide replaces the oil-soluble organic ligand on the surface of the second quantum dot, and then heat to form a second quantum dot layer 22;

[0085] Step B2: Deposit a first quantum dot on the second quantum dot layer 22 to obtain a first quantum dot film, wherein the surface of the first quantum dot is connected with an oil-soluble organic ligand; provide a solution of a thiol-containing compound, the solution of which includes a thiol-containing compound and a first solvent, place the thiol-containing compound solution on the first quantum dot film, perform ligand exchange, so that the thiol-containing compound replaces the oil-soluble organic ligand on the surface of the first quantum dot, and heat for the first time to form a first quantum dot layer 21, thereby obtaining a light-emitting layer 20.

[0086] The optoelectronic device 100 described in this application employs a solid-phase ligand exchange method for a double-layer quantum dot film. This method significantly alters the conductivity of the quantum dot layers through relatively small changes in ligand chemistry. Specifically, the first quantum dot layer 21, near the anode 10, uses a short-chain compound containing a thiol group to replace the oil-soluble organic ligands through ligand exchange, causing the energy level of the first quantum dot to shift upwards, which is beneficial for hole injection. The second quantum dot layer 22, near the cathode 30, uses a halide to replace the oil-soluble organic ligands through ligand exchange, effectively improving the charge transport of the second quantum dot. Furthermore, the solid-phase ligand exchange method allows for more complete ligand exchange, resulting in fewer or even no oil-soluble organic ligands in the prepared first and second quantum dot layers 21 and 22, thereby effectively improving the brightness and lifetime performance of the optoelectronic device 100.

[0087] The first quantum dot, the second quantum dot, the thiol-containing compound, the halide, the oil-soluble organic ligand, the first quantum dot layer 21, and the second quantum dot layer 22 are described above and will not be repeated here.

[0088] In some instances, the first quantum dot film is a dry film. In some instances, the second quantum dot film is a dry film.

[0089] The solvent in the solution containing the mercapto group is a first solvent, which includes, but is not limited to, one or more of acetonitrile, carbon tetrachloride, methyl acetate, ethyl acetate, and dichloroethane.

[0090] In the solution of the thiol-containing compound, the volume ratio of the thiol-containing compound to the first solvent is (0.5–2):10, for example, 0.5:10, 0.8:10, 1:10, 1.2:10, 1.3:10, 1.5:10, 1.6:10, 1.8:10, 2:10, and any range between two values. Within this range, the thiol-containing compound can effectively replace the oil-soluble organic ligands on the surface of the first quantum dot.

[0091] In some embodiments, the mass ratio of the first quantum dots in the first quantum dot film to the thiol-containing compound in the thiol-containing compound solution ranges from (7.5 to 8.5):(1.5 to 2.5), for example, 7.5:1.5, 7.5:2, 7.5:2.5, 8:1.5, 8:2, 8:2.5, 8.5:1.5, 8.5:2, 8.5:2.5, and any range between two values. This facilitates a more complete replacement of the oil-soluble organic ligands on the surface of the first quantum dots by the thiol-containing compound.

[0092] The solvent in the halide solution is a second solvent, which includes, but is not limited to, one or more of acetonitrile, carbon tetrachloride, methyl acetate, ethyl acetate, dichloroethane, and ethanol.

[0093] In the halide solution, the mass ratio of the halide to the second solvent is (0.5–2):10, for example, 0.5:10, 0.8:10, 1:10, 1.2:10, 1.3:10, 1.5:10, 1.6:10, 1.8:10, 2:10, and any range between two values. Within this range, it is beneficial for the halide to more fully replace the oil-soluble organic ligands on the surface of the second quantum dot.

[0094] In some embodiments, the mass ratio of the second quantum dots in the second quantum dot film to the halide in the halide solution ranges from (7.5 to 8.5):(1.5 to 2.5), for example, 7.5:1.5, 7.5:2, 7.5:2.5, 8:1.5, 8:2, 8:2.5, 8.5:1.5, 8.5:2, 8.5:2.5, and any range between two values. This facilitates the sufficient replacement of the oil-soluble organic ligands on the surface of the second quantum dots by the halide.

[0095] The first heating temperature is 80–120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or any range between two values; the first heating time is 2.5–10 min, for example, 2.5 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or any range between two values. Within this range, it is beneficial for the thiol-containing compound to more fully replace the oil-soluble organic ligands on the surface of the first quantum dot, and it is also beneficial for the prepared first quantum dot layer 21 to have better stability.

[0096] The second heating temperature is 80–120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or any range between two values; the second heating time is 15–40 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, or any range between two values. Within these ranges, it is beneficial for the halide to more fully replace the oil-soluble organic ligands on the surface of the second quantum dot, and it is also beneficial for the prepared second quantum dot layer 22 to have better stability.

[0097] In some instances, after placing the solution of the thiol-containing compound on the first quantum dot film and before the first heating, the process further includes a first settling period of 20–50 seconds, for example, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, or any range between two such values. This facilitates a more thorough replacement of the oil-soluble organic ligands on the surface of the first quantum dot by the thiol-containing compound.

[0098] In some instances, after the first settling period and before the first heating, the process includes: a first spin coating of the thiol-containing compound at a rotation speed of 1200–1800 rpm for 30–80 s. This allows the thiol-containing compound to more fully replace the oil-soluble organic ligands on the surface of the first quantum dot.

[0099] In some embodiments, the process further includes rinsing with a first cleaning agent after the first spin coating. The first cleaning agent includes, but is not limited to, one or more of carbon tetrachloride, methyl acetate, ethyl acetate, dichloroethane, ethanol, and toluene. This washes away displaced oil-soluble organic ligands and excess thiol-containing compounds.

[0100] In some instances, a second settling period is included after the halide solution is placed on the second quantum dot film and before the second heating. This settling period is 20–50 seconds, for example, 20, 25, 30, 35, 40, 45, 50 seconds, or any range between these values. This allows the halide to more fully replace the oil-soluble organic ligands on the surface of the second quantum dot.

[0101] In some instances, after the second settling period and before the second heating, a second spin-coating of the halide solution is performed at a speed of 1200–1800 rpm for 30–80 s. This allows the halide to more fully replace the oil-soluble organic ligands on the surface of the first quantum dot.

[0102] In some embodiments, the process further includes rinsing with a second cleaning agent after the second spin coating. The second cleaning agent includes, but is not limited to, one or more of carbon tetrachloride, methyl acetate, ethyl acetate, dichloroethane, ethanol, and toluene. This washes away displaced oil-soluble organic ligands and excess halides.

[0103] In some embodiments, the deposition of the first quantum dot to obtain the first quantum dot film comprises: providing a first quantum dot solution, the first quantum dot solution comprising a first quantum dot and a third solvent, depositing the first quantum dot solution, and performing a first annealing to obtain the first quantum dot film.

[0104] In some embodiments, the deposition of the second quantum dots to obtain the second quantum dot film comprises: providing a second quantum dot solution, the second quantum dot solution comprising the second quantum dots and a fourth solvent, depositing the second quantum dot solution, and performing a second annealing to obtain the second quantum dot film.

[0105] In some embodiments, the concentration of the first quantum dot solution is 5–50 mg / mL. Within this range, it exhibits good film-forming effect.

[0106] In some embodiments, the concentration of the second quantum dot solution is 5–50 mg / mL. Within this range, it exhibits good film-forming effect.

[0107] In some instances, the third solvent and the fourth solvent are each independently selected from one or more of oleic acid (OA), oleylamine (OLA), tri-n-octylamine (TOA), trioctylphosphine (TOP), tributylphosphine (TBUP), trihexylphosphine, and diphenyldioxane (DPP). It is understood that the third solvent and the fourth solvent may be the same or different.

[0108] In some embodiments, the temperature of the first annealing is 80–120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or any range between two values; the time of the first annealing is 2.5–10 min, for example, 2.5 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or any range between two values. Within these ranges, it is advantageous to prepare a first quantum dot layer 21 with good film-forming properties.

[0109] In some embodiments, the temperature of the second annealing is 80–120°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, or any range between two values; the time of the second annealing is 2.5–10 min, for example, 2.5 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, or any range between two values. Within these ranges, it is advantageous to prepare a second quantum dot layer 22 with good film-forming properties.

[0110] Please see Figure 2 In some embodiments, the first electrode is an anode 10 and the second electrode is a cathode 30. The fabrication of the light-emitting layer 20 on the first electrode includes: sequentially fabricating a hole transport layer 50 and a light-emitting layer 20 on the first electrode.

[0111] In some embodiments, the first electrode is an anode 10 and the second electrode is a cathode 30. The fabrication of the light-emitting layer 20 on the first electrode includes: sequentially fabricating a hole transport layer 50, a hole injection layer 60 and the light-emitting layer 20 on the first electrode.

[0112] In some embodiments, the first electrode is an anode 10 and the second electrode is a cathode 30. The fabrication of the second electrode on the light-emitting layer 20 includes: sequentially fabricating an electron transport layer 40 and a second electrode on the light-emitting layer 20.

[0113] In some embodiments, the first electrode is a cathode 30, the second electrode is an anode 10, and a light-emitting layer 20 is prepared on the first electrode: an electron transport layer 40 and a light-emitting layer 20 are sequentially prepared on the first electrode.

[0114] In some embodiments, the first electrode is a cathode 30 and the second electrode is an anode 10. The fabrication of the second electrode on the light-emitting layer 20 includes: sequentially fabricating a hole transport layer 50 and the second electrode on the light-emitting layer 20.

[0115] In some embodiments, the first electrode is a cathode 30 and the second electrode is an anode 10. The fabrication of the second electrode on the light-emitting layer 20 includes: sequentially fabricating a hole transport layer 50, a hole injection layer 60 and a second electrode on the light-emitting layer 20.

[0116] The anode 10, the cathode 30, the electron transport layer 40, the hole transport layer 50, and the hole injection layer 60 are as described above and will not be repeated here.

[0117] The methods for preparing the second electrode, electron transport layer 40, hole transport layer 50, and hole injection layer 60 described in this application can be implemented using conventional techniques in the art, such as chemical or physical methods. Chemical methods include chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical methods include physical deposition and solution methods. Physical deposition methods include thermal evaporation deposition, electron beam evaporation deposition, magnetron sputtering, multi-arc ion deposition, physical vapor deposition, atomic layer deposition, and pulsed laser deposition, etc.; solution methods can include spin coating, printing, inkjet printing, blade coating, dip coating, immersion coating, spraying, roller coating, casting, slot coating, and strip coating, etc.

[0118] It is understood that when the optoelectronic device 100 also includes functional layers that are conventionally used in optoelectronic devices to help improve the performance of the optoelectronic device, such as electron blocking layers, hole blocking layers, interface modification layers, etc., the method of fabricating the optoelectronic device 100 may also include the step of fabricating the above-mentioned functional layers using conventional techniques in the art.

[0119] Thirdly, this application also relates to a display device, which includes the optoelectronic device 100.

[0120] The display device can be any electronic product with display function, including but not limited to smartphones, tablets, laptops, digital cameras, digital camcorders, smart wearable devices, smart weighing scales, in-vehicle displays, televisions, or e-book readers. Among them, smart wearable devices can be, for example, smart bracelets, smartwatches, virtual reality (VR) headsets, etc.

[0121] The present application will be specifically described below through specific embodiments. The following embodiments are only some embodiments of the present application and are not intended to limit the present application.

[0122] Example 1

[0123] Step S1: First, ultrasonically clean the substrate coated with ITO anode with acetone and ethanol for 15 minutes, then clean it again with deionized water, dry it on a heating plate at 150°C for 10 minutes, and finally irradiate it with ultraviolet light (UV) for 20 minutes to improve the work function and surface energy of ITO.

[0124] Step S2: Place the cleaned substrate into the glove box, spin coat the anode with PEDOT:PSS material (mass fraction 2.8%) at 3000 rpm for 30 s, and then heat it on a 150°C heating plate for 20 min to obtain a hole injection layer with a thickness of 20 nm.

[0125] Step S3: Spin-coat TFB material (concentration of 6.5 mg / mL) onto the hole injection layer at 3000 rpm for 30 s, and then heat it on a 120°C heating plate for 20 min to obtain a hole transport layer with a thickness of 20 nm.

[0126] Step S4: Spin-coat a first quantum dot ZnCdSe blue quantum dot (QD) solution (concentration of 10 mg / mL) onto the hole transport layer. The ZnCdSe blue quantum dots are connected to oleic acid ligands. Spin-coat at 1500 rpm for 30 s, then heat on a 100°C heating plate for 5 min to obtain a first quantum dot film with a thickness of 20 nm.

[0127] Step S5: Add 1 mL of acetonitrile solution of 1,2-ethylenedithiol (volume ratio of 1,2-ethylenedithiol to acetonitrile is 1:10) to the first quantum dot film, let it stand for 30 s, then spin coat at 1500 rpm for 20 s, rinse three times with acetonitrile, and then heat on a hot plate at 100°C for 20 min to obtain the first quantum dot layer. The first quantum dot layer includes the first quantum dots and 1,2-ethylenedithiol (first ligand), wherein the mass ratio of the first quantum dots to the first ligand is 8:2.

[0128] Step S6: Spin-coat a second quantum dot ZnCdSe blue quantum dot (QD) solution (concentration of 10 mg / mL) onto the first quantum dot layer. The ZnCdSe blue quantum dots are connected to oleic acid ligands. Spin-coat at 1500 rpm for 30 s, then heat on a 100°C heating plate for 5 min to obtain a second quantum dot film with a thickness of 20 nm.

[0129] Step S7: Add 1 mL of thionyl chloride acetonitrile solution (thionyl chloride to acetonitrile mass ratio of 1:10) to the second quantum dot film, let stand for 30 s, then spin coat at 1500 rpm for 20 s, rinse three times with toluene, and then heat on a 100°C hot plate for 20 min to form a second quantum dot layer, thus obtaining a light-emitting layer comprising a first quantum dot layer and a second quantum dot layer. The second quantum dot layer comprises a second quantum dot and a thionyl chloride (second ligand), wherein the mass ratio of the second quantum dot to the second ligand is 8:2.

[0130] Step S8: Spin-coat ZnO material (ethanol colloid with a concentration of 30 mg / mL) onto the second quantum dot layer at a speed of 4000 rpm for 30 s, and then heat it on an 80°C heating plate for 10 min to obtain an electron transport layer with a thickness of 35 nm.

[0131] Step S9: Through thermal evaporation, the vacuum level is not higher than 3×10⁻⁶. -4Pa is used to vapor-deposit Al at a speed of 1 angstrom / second for 100 seconds to obtain a cathode with a thickness of 100 nm. After encapsulation, an optoelectronic device is obtained, which is a quantum dot light-emitting diode.

[0132] Example 2

[0133] This embodiment is basically the same as that of Embodiment 1, except that in this embodiment, 1,8-octanedithiol is used instead of 1,2-ethanedithiol in Embodiment 1.

[0134] Example 3

[0135] This embodiment is basically the same as Embodiment 1, except that in this embodiment, ethanethiol is used instead of 1,2-ethanedithiol in Embodiment 1.

[0136] Example 4

[0137] This embodiment is basically the same as that of Embodiment 1, except that cyclohexanethiol is used to replace 1,2-ethanedithiol in Embodiment 1.

[0138] Example 5

[0139] This embodiment is basically the same as that of Embodiment 1, except that ZnBr2 is used to replace thionyl chloride in Embodiment 1.

[0140] Example 6

[0141] This embodiment is basically the same as that of Embodiment 1, except that in this embodiment, NH4I2 is used to replace thionyl chloride in Embodiment 1.

[0142] Example 7

[0143] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass ratio of the first quantum dot to 1,2-ethylenedithiol in the first quantum dot layer is 7.5:2.5.

[0144] Example 8

[0145] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass ratio of the first quantum dot to 1,2-ethylenedithiol in the first quantum dot layer is 8.5:1.5.

[0146] Example 9

[0147] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass ratio of the second quantum dot to thionyl chloride in the second quantum dot layer is 7.5:2.5.

[0148] Example 10

[0149] This embodiment is basically the same as Embodiment 1, except that in this embodiment, the mass ratio of the second quantum dot to thionyl chloride in the second quantum dot layer is 8.5:1.5.

[0150] Example 11

[0151] This embodiment is basically the same as Embodiment 1, except that the temperature in step S5 is 80°C in this embodiment.

[0152] Example 12

[0153] This embodiment is basically the same as Embodiment 1, except that the temperature in step S5 is 120°C in this embodiment.

[0154] Example 13

[0155] This embodiment is basically the same as Embodiment 1, except that the temperature in step S7 is 80°C in this embodiment.

[0156] Example 14

[0157] This embodiment is basically the same as Embodiment 1, except that the temperature in step S7 is 120°C in this embodiment.

[0158] Example 15

[0159] This embodiment is basically the same as Embodiment 1, except that in this embodiment, CdSe red quantum dots are used to replace the blue quantum dots ZnCdSe in Embodiment 1.

[0160] Example 16

[0161] This embodiment is basically the same as Embodiment 1, except that in this embodiment, ZnCdSe green quantum dots are used to replace the blue quantum dots ZnCdSe in Embodiment 1.

[0162] Comparative Example 1

[0163] This comparative example is basically the same as Example 1, except that steps S5 and S7 are not included in this comparative example.

[0164] Comparative Example 2

[0165] This comparative example is basically the same as Example 15, except that steps S5 and S7 are not included in this comparative example.

[0166] Comparative Example 3

[0167] This comparative example is basically the same as Example 16, except that steps S5 and S7 are not included in this comparative example.

[0168] Comparative Example 4

[0169] This comparative example is basically the same as Example 1, except that step S5 is not included in this comparative example.

[0170] Comparative Example 5

[0171] This comparative example is basically the same as Example 1, except that step S7 is not included in this comparative example.

[0172] The maximum brightness L of the optoelectronic devices in Examples 1-16 and Comparative Examples 1-5 was measured respectively. max Lifetime T95 and lifetime T95@1000nit tests were conducted. Test results are shown in Table 1.

[0173] The content of oil-soluble ligands (oleic acid) in the first quantum dot layer and the second quantum dot layer in the optoelectronic devices of Examples 1-16 and Comparative Examples 1-5 was tested, and the test results are shown in Table 1.

[0174] The maximum brightness was measured using a PR650 luminance meter, with a constant driving current of 1mA.

[0175] The lifetime T95 and lifetime T95@1000nit test methods are as follows: In CDA gas, under constant current drive, the time it takes for the device brightness to decay to a certain percentage of its maximum brightness is measured. The time for the brightness to decay to 95% of the maximum brightness is defined as T95, and this lifetime is the measured lifetime. To shorten the lifetime testing cycle, device lifetime testing is usually performed at high brightness by accelerating device aging, and the lifetime at low brightness is obtained by fitting the decay fitting formula. For example, the lifetime at 1000 nits is denoted as T95@1000nits, and the calculation formula is as follows:

[0176]

[0177] Among them, T95 L The lifespan at low brightness is typically taken as the lifespan at 1000 nits, T95. H The lifetime at high brightness, i.e., the measured lifetime, L H L is the maximum brightness that the device accelerates to. L Typically, it is 1000 nits, where A is the acceleration factor, taken as 1.7. The constant current is 1 mA.

[0178] The above test conditions were: conducted at room temperature with an air humidity of 50%.

[0179] The test method for oil-soluble ligands is as follows: thin films are prepared on glass substrates using the preparation methods of the first quantum dot layer and the second quantum dot layer in the optoelectronic devices of Examples 1-16 and Comparative Examples 1-5, respectively. The films are then scraped off and subjected to thermogravimetric analysis. The weight loss temperature range of oleic acid is 200-450℃, while the weight loss of other strongly coordinating ligands is greater than 450℃.

[0180] Table 1:

[0181]

[0182]

[0183] As shown in Table 1:

[0184] Compared to the optoelectronic device of Comparative Example 1, the optoelectronic devices of Examples 1-14 exhibit higher maximum brightness and longer lifetime; compared to the optoelectronic device of Comparative Example 2, the optoelectronic device of Example 15 exhibits higher maximum brightness and longer lifetime; and compared to the optoelectronic device of Comparative Example 3, the optoelectronic device of Example 16 exhibits higher maximum brightness and longer lifetime. It is evident that using short-chain compounds containing thiol groups for ligand exchange to replace oil-soluble organic ligands during the preparation of the first quantum dot layer, and using halides for ligand exchange to replace oil-soluble organic ligands during the preparation of the second quantum dot layer, can effectively improve the brightness and lifetime of the optoelectronic device. The reason may be that the first quantum dot layer near the anode uses short-chain compounds containing thiol groups to replace the oil-soluble organic ligands through ligand exchange, which shifts the energy level of the first quantum dot upward, facilitating hole injection; the second quantum dot layer near the cathode uses halides to replace the oil-soluble organic ligands through ligand exchange, which can effectively improve the charge transport of the second quantum dot; and the solid-phase ligand exchange method can more fully perform ligand exchange, resulting in fewer or even no oil-soluble organic ligands in the prepared first and second quantum dot layers.

[0185] Compared to the optoelectronic devices in Comparative Examples 4-5, the optoelectronic devices in Examples 1-14 exhibit higher maximum brightness and longer lifetime. It is evident that using short-chain thiol-containing compounds for ligand exchange to replace oil-soluble organic ligands during the preparation of the first quantum dot layer, and using halides for ligand exchange to replace oil-soluble organic ligands during the preparation of the second quantum dot layer, can effectively improve the brightness and lifetime of the optoelectronic device. This is likely because using short-chain thiol-containing compounds for ligand exchange in the first quantum dot layer near the anode shifts the energy level of the first quantum dot upwards, facilitating hole injection; while using halides for ligand exchange in the second quantum dot layer near the cathode effectively improves the charge transport of the second quantum dot. Thus, the brightness and lifetime of the optoelectronic device can be improved more effectively.

[0186] The technical solutions provided by the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optoelectronic device, characterized in that, The device comprises an anode, a light-emitting layer, and a cathode stacked sequentially. The light-emitting layer includes a first quantum dot layer and a second quantum dot layer stacked together. The first quantum dot layer is located between the anode and the second quantum dot layer. The material of the first quantum dot layer includes a first quantum dot and a first ligand, wherein the first ligand is a compound containing a thiol group. The material of the second quantum dot layer includes a second quantum dot and a second ligand, wherein the second ligand is a halide.

2. The optoelectronic device as described in claim 1, characterized in that, The first ligand is coordinated with the first quantum dot; And / or, the second ligand is coordinated with the second quantum dot; And / or, the average thickness of the first quantum dot layer is 15–25 nm; And / or, the average thickness of the second quantum dot layer is 15–25 nm; And / or, the average particle size of the first quantum dot is 11–13 nm; And / or, the average particle size of the second quantum dot is 11–13 nm; And / or, in the first quantum dot layer, the mass ratio of the first quantum dot to the first ligand is in the range of (8-9):(1-2); And / or, in the second quantum dot layer, the mass ratio of the second quantum dot to the second ligand is in the range of (8-9):(1-2); And / or, the halide includes one or more of zinc halide, magnesium halide, ammonium halide, thionyl halide, phosphorus trihalide, and phosphorus trihalomethane; And / or, the thiol-containing compound includes one or more of saturated aliphatic thiols with a main chain of 1 to 8 carbon atoms, unsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms, and alicyclic thiols with a ring number of 3 to 8; optionally, the saturated aliphatic thiols with a main chain of 1 to 8 carbon atoms include one or more of monobasic saturated aliphatic thiols with a main chain of 1 to 8 carbon atoms and polybasic saturated aliphatic thiols with a main chain of 2 to 8 carbon atoms, and the unsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms include one or more of monobasic unsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms and polybasic unsaturated aliphatic thiols with a main chain of 2 to 8 carbon atoms.

3. The optoelectronic device as described in claim 2, characterized in that, The monobasic saturated aliphatic thiols with 1 to 8 carbon atoms in their main chain include one or more of the following: methanethiol, ethanethiol, n-propanethiol, isopropanethiol, n-butanethiol, isobutanethiol, sec-butanethiol, 2-methyl-1-butanethiol, 3-methyl-2-butanethiol, tert-butanethiol, 1-pentanethiol, 2-pentanethiol, isopentanethiol, 1-hexanethiol, 1-heptanethiol, 1-octanethiol, sec-octanethiol, isooctanethiol, tert-nonylthiol, and cyclopropylmethanethiol. And / or, the polybasic saturated aliphatic thiols with 2 to 8 carbon atoms in the main chain include one or more of 1,2-ethanedithiol, 1,3-propanedithiol, 2,3-butanedithiol, 1,2-butanedithiol, 1,4-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, and 1,8-octanedithiol; And / or, the unsaturated aliphatic thiols with 2 to 8 carbon atoms in the main chain include one or more of allyl thiols, allyl butyl thiols, allyl pentyl thiols, 3-methyl-2-buten-1-thiols, 3,7-dimethyl-2,6-octadien-1-thiols, and prop-2-yn-1-thiols. And / or, the alicyclic thiols having 3 to 8 ring atoms include one or more of cyclopropanethiol, cyclopentanethiol, cyclohexanethiol, cycloheptanethiol, and cyclooctanethiol; And / or, the zinc halide includes one or more of ZnCl2, ZnBr2, and ZnI2; And / or, the magnesium halide includes one or more of MgCl2, MgBr2, and MgI2; And / or, the ammonium halide includes one or more of NH4Cl, NH4Br, and NH4I2; And / or, the thionyl halide includes one or more of thionyl chloride and thionyl bromide; And / or, the phosphorus trihalides include one or more of phosphorus trichloride and phosphorus tribromide; And / or, the phosphorus trihalomethane includes one or more of phosphorus oxychloride and phosphorus tribromooxychloride.

4. The optoelectronic device as described in claim 1, characterized in that, The surface of the first quantum dots in the first quantum dot layer is not connected to an oil-soluble organic ligand; or, the surface of the first quantum dots in the first quantum dot layer is also coordinated with an oil-soluble organic ligand, and the content of the oil-soluble organic ligand is less than or equal to 12 wt%; and / or The surface of the second quantum dot in the second quantum dot layer is not connected to an oil-soluble organic ligand; or, the surface of the second quantum dot in the second quantum dot layer is also coordinated with an oil-soluble organic ligand, and the content of the oil-soluble organic ligand is less than or equal to 12 wt%.

5. The optoelectronic device as described in claim 4, characterized in that, The oil-soluble organic ligands include substituted or unsubstituted C6-C. 24 Fatty acids, substituted or unsubstituted C6-C 24 Fatty amines, substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides, substituted or unsubstituted C8-C8 phosphine oxides 20 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphates, substituted or unsubstituted C6-C 24 Aliphatic phosphorous acid and substituted or unsubstituted C6-C 24 At least one of the fatty phosphites, wherein the substituent is selected from at least one of C1-C6 alkyl, C1-C6 alkoxy, and halogen, wherein, The substituted or unsubstituted C6-C 24 Fatty acids include at least one of the following: decanoic acid, undecenoic acid, tetradecanoic acid, oleic acid, linoleic acid, and stearic acid; And / or, the substituted or unsubstituted C6-C 24 Fatty amines include at least one of oleylamine, octadecylamine, octylamine, dioctylamine, and trioctylamine; And / or, the substituted or unsubstituted C6-C 24 Aliphatic phosphines include trioctylphosphine; And / or, the substituted or unsubstituted C6-C 24 Aliphatic phosphine oxides include tri-n-octylphosphine oxide.

6. The optoelectronic device as described in claim 1, characterized in that, The first quantum dot and the second quantum dot are each independently selected from one or more of the following: single-structure quantum dots, core-shell structure quantum dots, and perovskite quantum dots. The core-shell structure quantum dot comprises one or more shell layers. The material of the single-structure quantum dot, the core material of the core-shell structure quantum dot, and the shell material of the core-shell structure quantum dot respectively include one or more of group II-VI compounds, group IV-VI compounds, group III-V compounds, and group I-III-VI compounds. The group II-VI compounds include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, CdSeS, CdSeTe, and CdSeO. One or more of the following compounds: dSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, and HgZnSTe; the IV-VI group compounds include SnS, SnSe, SnTe, PbS, PbSe, PbTe, SnSeS, and SnSe. Te, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, SnPbSSe, SnPbSeTe, SnPbSTe; the III-V compounds include one or more of GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, GaNP, GaNAs, GaNSb, GaPAs, GaPSb, AlNP, AlNAs, AlNSb, AlPAs, AlPSb, InNP, InNAs, InNSb, InPAs, InPSb, G One or more of the following compounds are selected: aAlNP, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNP, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNP, InAlNAs, InAlNSb, InAlPAs, and InAlPSb; the I-III-VI group compounds include one or more of CuInS2, CuInSe2, and AgInS2; the perovskite quantum dots include doped or undoped inorganic perovskite quantum dots, or organic-inorganic hybrid perovskite quantum dots, wherein the general structural formula of the inorganic perovskite quantum dots is AMX3, where A is Cs. + Ions, where M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2+ Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; the general structural formula of the organic-inorganic hybrid perovskite quantum dots is BMX3, where B is an organic amine cation, including CH3(CH2). n-2 NH3 + Or [NH3(CH2)] n NH3] 2+ Where n≥2, M is a divalent metal cation, including Pb 2+ Sn 2+ Cu 2+ Ni 2+ Cd 2+ Cr 2+ Mn 2+ Co 2+ Fe 2+ 、Ge 2+ Yb 2 + Eu 2+ One or more of them, where X is a halide anion, including Cl. - ,Br - I - One or more of the following; The anode and the cathode are each independently selected from doped metal oxide electrodes, composite electrodes, graphene electrodes, carbon nanotube electrodes, elemental metal electrodes, or alloy electrodes. The material of the doped metal oxide electrode is selected from at least one of indium-doped tin oxide, fluorine-doped tin oxide, antimony-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, magnesium-doped zinc oxide, and aluminum-doped magnesium oxide. The composite electrode is selected from AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, or ZnS / Al / ZnS. The material of the elemental metal electrode is selected from at least one of Ag, Al, Mg, Au, Pt, Ca, and Ba; and / or The optoelectronic device further includes an electron transport layer located between the cathode and the light-emitting layer. The electron transport layer is made of one or more of N-type inorganic particles and N-type organic materials. The N-type inorganic particles are made of one or more of a first-doped metal oxide particle, a first-undoped metal oxide particle, a group IIB-VIA semiconductor material, a group IIIA-VA semiconductor material, and a group IB-IIIA-VIA semiconductor material. The first-undoped metal oxide particle is made of one or more of ZnO, TiO2, SnO2, ZrO2, and Ta2O5. The metal oxide in the first-doped metal oxide particle is ZnO, TiO2, SnO2, ZrO2, or Ta2O5. One or more of Al2O3, wherein the doping element in the first doped metal oxide particles includes one or more of Al, Mg, Li, Mn, Y, La, Cu, Ni, Zr, Ce, In, and Ga; the IIB-VIA group semiconductor material includes one or more of ZnS, ZnSe, and CdS; the IIIA-VA group semiconductor material includes one or more of InP and GaP; the IB-IIIA-VIA group semiconductor material includes one or more of CuInS and CuGaS; the N-type organic material includes one or more of quinoxaline compounds, imidazole compounds, triazine compounds, fluorene-containing compounds, hydroxyquinoline compounds, and fullerene derivatives (PCBM); and / or The optoelectronic device further includes a hole transport layer and a hole injection layer located between the anode and the light-emitting layer. The materials of the hole transport layer and the hole injection layer each independently include one or more of P-type inorganic particles and P-type organic materials. The P-type inorganic particles include one or more of second-doped metal oxide particles, second-undoped metal oxide particles, metal sulfides, metal selenides, and metal nitrides. The metal oxides in the second-doped metal oxide particles and the second-undoped metal oxide particles each independently include one or more of MoO3, WO3, NiO, CrO3, CuO, Cu2O, and V2O5. The doping elements in the particles include one or more of Mo, W, Ni, Cr, Cu, and V; the metal sulfide includes one or more of CuS, MoS3, and WS3; the metal selenide includes one or more of MoSe3 and WSe3; the metal nitride includes p-type gallium nitride; and the p-type organic semiconductor material includes 4,4'-N,N'-dicarbazolyl-biphenyl, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine, N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine, poly( N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)spiro, N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine, 4,4',4'-tris(N-carbazolyl)-triphenylamine, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))], poly(N-vinylcarbazole) (PVK) and its derivatives, N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'- Biphenyl-4-4'-diamine, spiroNPB, poly(phenylenevinylene), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene], 2,2',7,7'-tetratetra[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene, 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], 1,3-di(carbazole-9-yl)benzene, polyaniline, polypyrrole, poly(p)phenylenevinylene, aromatic tertiary amines, polynuclear aromatic tertiary amines, 4,4'-bis(p-carbazole)-1,1'-biphenyl compounds, N,N,N',The following are selected from the following: N'-tetraarylbenzidine, PEDOT:PSS and its derivatives, polymethacrylate and its derivatives, poly(9,9-octylfluorene) and its derivatives, poly(spirofluorene) and its derivatives, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene, PEDOT, PEDOT:PSS, PEDOT:PSS derivatives doped with s-MoO3, 4,4',4'-tris(N-3-methylphenyl-N-phenylamino)triphenylamine, tetracyanoquinone dimethane, doped graphene, undoped graphene, C60, and copper phthalocyanine.

7. A method for fabricating an optoelectronic device, characterized in that, Includes the following steps: Provide the first electrode; A light-emitting layer is prepared on the first electrode; A second electrode is fabricated on the light-emitting layer to obtain a photoelectric device; Wherein, the first electrode is the anode, and the fabrication of the light-emitting layer on the first electrode includes: A first quantum dot is deposited on the first electrode to obtain a first quantum dot film, wherein an oil-soluble organic ligand is attached to the surface of the first quantum dot; a solution of a thiol-containing compound is provided, the thiol-containing compound solution comprising a thiol-containing compound and a first solvent, the thiol-containing compound solution is disposed on the first quantum dot film, and a first heating is performed to form a first quantum dot layer; and A second quantum dot is deposited on the first quantum dot layer to obtain a second quantum dot film, wherein the surface of the second quantum dot is connected with an oil-soluble organic ligand; a halide solution is provided, the halide solution including a halide and a second solvent, the halide solution is placed on the second quantum dot film, and then heated to form a second quantum dot layer, thereby obtaining a light-emitting layer; or, Wherein, the first electrode is a cathode, the second electrode is an anode, and the fabrication of the light-emitting layer on the first electrode includes: A second quantum dot is deposited on the first electrode to obtain a second quantum dot film, wherein the surface of the second quantum dot is connected with an oil-soluble organic ligand; a halide solution is provided, the halide solution comprising a halide and a second solvent, the halide solution is disposed on the second quantum dot film, and then heated to form a second quantum dot layer; and A first quantum dot is deposited on the second quantum dot layer to obtain a first quantum dot film, wherein an oil-soluble organic ligand is attached to the surface of the first quantum dot; a solution of a thiol-containing compound is provided, the solution of the thiol-containing compound comprising a thiol-containing compound and a first solvent, the thiol-containing compound solution is placed on the first quantum dot film, and a first heating is performed to form a first quantum dot layer, thereby obtaining a light-emitting layer.

8. The preparation method according to claim 7, characterized in that, The first quantum dot film is a dry film; And / or, the second quantum dot film is a dry film; And / or, the first solvent includes one or more of acetonitrile, carbon tetrachloride, methyl acetate, ethyl acetate, and dichloroethane; And / or, the second solvent includes one or more of acetonitrile, carbon tetrachloride, methyl acetate, ethyl acetate, dichloroethane, and ethanol; And / or, in the solution of the thiol-containing compound, the volume ratio of the thiol-containing compound to the first solvent is (0.5-2):10; And / or, in the halide solution, the mass ratio of the halide to the second solvent is (0.5-2):10; And / or, the mass ratio of the first quantum dot in the first quantum dot film to the thiol-containing compound in the thiol-containing compound solution is in the range of (7.5–8.5):(1.5–2.5); And / or, the mass ratio of the second quantum dot in the second quantum dot film to the halide in the halide solution is in the range of (7.5–8.5):(1.5–2.5); And / or, the temperature of the first heating is 80–120°C, and the heating time is 2.5–10 min; And / or, the temperature of the second heating is 80–120°C, and the heating time is 15–40 min; And / or, after placing the solution of the thiol-containing compound on the first quantum dot film and before the first heating, the method further includes: a first settling period of 20 to 50 seconds; And / or, after the halide solution is placed on the second quantum dot film and before the second heating, a second settling period of 20 to 50 seconds is included; And / or, the deposition of the first quantum dot to obtain the first quantum dot film comprises: providing a first quantum dot solution, the first quantum dot solution comprising a first quantum dot and a third solvent, depositing the first quantum dot solution, and performing a first annealing to obtain the first quantum dot film; And / or, the deposition of the second quantum dots to obtain the second quantum dot film comprises: providing a second quantum dot solution, the second quantum dot solution comprising the second quantum dots and a fourth solvent, depositing the second quantum dot solution, and performing a second annealing to obtain the second quantum dot film.

9. The preparation method according to claim 8, characterized in that, After the first settling and before the first heating, the process further includes: performing a first spin coating on the compound containing thiol groups, wherein the first spin coating speed is 1200-1800 rpm and the time is 30-80 s; And / or, after the second settling and before the second heating, the method further includes: performing a second spin coating on the halide solution, wherein the second spin coating is performed at a speed of 1200 to 1800 rpm for a time of 30 to 80 s; And / or, the concentration of the first quantum dot solution is 5–50 mg / mL; And / or, the concentration of the second quantum dot solution is 5–50 mg / mL; And / or, the third solvent and the fourth solvent are each independently selected from one or more of oleic acid, oleylamine, tri-n-octylamine, trioctylphosphine, tributylphosphine, trihexylphosphine, and diphenylphosphine; And / or, the temperature of the first annealing is 80–120°C, and the time of the first annealing is 2.5–10 min; And / or, the temperature of the second annealing is 80 to 120°C, and the time of the second annealing is 2.5 to 10 minutes.

10. The preparation method according to claim 7, characterized in that, The first electrode is an anode, and the second electrode is a cathode. The fabrication of a light-emitting layer on the first electrode includes: sequentially fabricating a hole transport layer and a light-emitting layer on the first electrode, or sequentially fabricating a hole transport layer, a hole injection layer, and a light-emitting layer on the first electrode; and / or, the fabrication of a second electrode on the light-emitting layer includes: sequentially fabricating an electron transport layer and a second electrode on the light-emitting layer. Alternatively, the first electrode is a cathode and the second electrode is an anode, and a light-emitting layer is prepared on the first electrode: an electron transport layer and a light-emitting layer are prepared sequentially on the first electrode; and / or, preparing a second electrode on the light-emitting layer includes: preparing a hole transport layer and a second electrode sequentially on the light-emitting layer, or preparing a hole transport layer, a hole injection layer and a second electrode sequentially on the light-emitting layer.

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