Light-emitting apparatus, manufacturing method therefor, and display device

Abstract

The embodiments of the present disclosure provide a light-emitting apparatus, a manufacturing method therefor, and a display device. The light-emitting apparatus comprises an anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a cathode, which are arranged in a stacked manner, wherein the electron transport layer is made of inorganic metal oxide nanoparticles, and hydroxyls and soluble groups that modify the inorganic metal oxide nanoparticles, the number of hydroxyls being greater than that of soluble groups; and the infrared spectrum of the electron transport layer has no obvious C-H vibration peak within the range of 2750 cm-1 to 3000 cm-1.

Description

Light-emitting device, manufacturing method thereof, and display device Technical Field

[0001] The present disclosure relates to the field of display technology, and in particular to a light-emitting device, a manufacturing method thereof, and a display apparatus. Background Art

[0002] Quantum dots (QDs), also known as nanocrystals, are nanoparticles composed of Group II-VI or Group III-V elements. They typically range in size from 1 to 20 nm. Due to the quantum confinement of electrons and holes, the continuous energy band structure is transformed into a discrete energy level structure, allowing them to emit fluorescence upon stimulation.

[0003] With the in-depth development of quantum dot preparation technology, the stability and luminous efficiency of quantum dots are constantly improving, the research on quantum dot light-emitting diodes (QLED) is constantly deepening, and the application prospects of QLED in the display field are becoming increasingly bright.

[0004] Summary of the Invention

[0005] The present disclosure provides a light-emitting device, a manufacturing method thereof, and a display device. The specific solutions are as follows:

[0006] The present disclosure provides a light-emitting device comprising a stacked anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode. The electron transport layer comprises inorganic metal oxide nanoparticles and hydroxyl groups and solubility groups that modify the inorganic metal oxide nanoparticles. The number of the hydroxyl groups is greater than the number of the solubility groups. The infrared spectrum of the electron transport layer is 2750 cm -1 ~3000cm -1 There is no obvious CH vibration peak in the range.

[0007] In a possible implementation, in the above-mentioned light-emitting device provided by the embodiment of the present disclosure, in the infrared spectrum of the electron transport layer, for the same infrared spectrum curve, at 2500cm -1 ~2700cm -1 The average value of the vertical coordinate of each absorption peak in the range is d1, at 3450cm -1 ~3650cm -1 The average value of the vertical coordinates of each absorption peak in the range is d2, 0.2≤(|d1-d2| / d1)≤0.5.

[0008] In a possible implementation, in the above-mentioned light-emitting device provided by the embodiment of the present disclosure, in the X-ray photoelectron spectroscopy analysis of the electron transport layer, N1s has no obvious characteristic peaks at 399.5 eV and 402 eV.

[0009] In a possible implementation, in the above-mentioned light-emitting device provided by the embodiment of the present disclosure, in the X-ray photoelectron spectroscopy analysis of the electron transport layer, Zn 2p has an obvious characteristic peak at 1022.5-1025 eV.

[0010] In a possible implementation, in the above-mentioned light-emitting device provided by the embodiment of the present disclosure, the solubility group includes ethanolamine.

[0011] In a possible implementation, in the above-mentioned light-emitting device provided in the embodiment of the present disclosure, the material of the quantum dot light-emitting layer includes a quantum dot body and hydroxyl groups and ligands coordinated and connected to the surface of the quantum dot body, and the number of the hydroxyl groups is greater than the number of the ligands.

[0012] In a possible implementation, in the above-mentioned light-emitting device provided in the embodiment of the present disclosure, the ligand includes at least one of oleic acid, oleylamine, and thiol.

[0013] Correspondingly, an embodiment of the present disclosure further provides a display device, comprising any of the above-mentioned light-emitting devices provided by the embodiment of the present disclosure.

[0014] Accordingly, the embodiment of the present disclosure further provides a method for manufacturing a light-emitting device, which is used to manufacture any of the light-emitting devices described above in the embodiment of the present disclosure, the manufacturing method comprising manufacturing a stacked anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode; wherein,

[0015] The material of the electron transport layer includes inorganic metal oxide nanoparticles and hydroxyl groups and solubility groups that modify the inorganic metal oxide nanoparticles. The number of the hydroxyl groups is greater than the number of the solubility groups. The infrared spectrum of the electron transport layer is 2750 cm -1 ~3000cm -1 There is no obvious CH vibration peak in the range.

[0016] In a possible implementation, in the above-mentioned manufacturing method provided in the embodiment of the present disclosure, manufacturing the electron transport layer specifically includes:

[0017] forming an electron transport layer on the quantum dot light-emitting layer or the cathode;

[0018] The device having the electron transport layer is subjected to water vapor treatment so that the number of the hydroxyl groups on the surface of the inorganic metal oxide nanoparticles is greater than the number of the solubility groups; wherein the water vapor content during the water vapor treatment is 30% to 50%. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic structural diagram of a light-emitting device provided in an embodiment of the present disclosure;

[0020] FIG2 is a schematic diagram of the material structure of the electron transport layer;

[0021] FIG3 is a schematic diagram of infrared spectrum analysis of an electron transport layer;

[0022] FIG4 is a schematic diagram of infrared spectrum analysis of an electron transport layer;

[0023] FIG5 is a schematic diagram of X-ray photoelectron spectroscopy analysis of an electron transport layer;

[0024] FIG6 is a schematic diagram of X-ray photoelectron spectroscopy analysis of an electron transport layer;

[0025] FIG7 is a schematic diagram of the structure of the material of the quantum dot light-emitting layer;

[0026] FIG8 is another structural schematic diagram of a light emitting device provided in an embodiment of the present disclosure;

[0027] FIG9 is a current density-voltage (IV) relationship diagram corresponding to the light-emitting devices of the comparative example and Examples 1-3, respectively;

[0028] FIG10 is a current efficiency-brightness relationship diagram corresponding to the light-emitting devices of the comparative example and embodiments 1-3, respectively. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. And in the absence of conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0030] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the usual meanings understood by persons of ordinary skill in the field to which this disclosure belongs. The words “include” or “comprise” and the like used in this disclosure mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. The words “connect” or “connected” and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Inside”, “outside”, “upper”, “lower”, etc. are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0031] It should be noted that the sizes and shapes of the figures in the accompanying drawings do not reflect the actual scale and are only for the purpose of illustrating the present disclosure. The same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions.

[0032] Quantum dots, as a new type of luminescent material, offer advantages such as high light color purity, high quantum efficiency, adjustable light color, and long lifespan, making them a research hotspot for new LED luminescent materials. Consequently, quantum dot light-emitting diodes (QLEDs), which use quantum dot materials as the luminescent layer, have become a major research focus for new display devices.

[0033] AMQLED has also received more and more attention due to its potential advantages in wide color gamut and long life. Its research is becoming increasingly in-depth, and its quantum efficiency is constantly improving, basically reaching the level of industrialization. Further adopting new processes and technologies to realize its industrialization has become a future trend.

[0034] Through research, the inventors found that current QLED devices usually require voltage to be applied first and undergo an electrical aging process in advance to significantly reduce the device's startup voltage and improve luminous efficiency.

[0035] Specifically, in the related art, when fabricating an electron transport layer, the material of the electron transport layer includes inorganic metal oxide nanoparticles (e.g., ZnO) and solubility groups (M) that modify the inorganic metal oxide nanoparticles (ZnO), such as ethanolamine ligands. However, the resulting electron transport layer generally has poor conductivity. To improve the luminous efficiency of light-emitting devices, it is necessary to first apply a voltage to the light-emitting device to perform an electrical aging process to reduce the turn-on voltage of the light-emitting device.

[0036] The embodiment of the present disclosure provides a light-emitting device, as shown in FIG1 , comprising a stacked anode 1, a hole transport layer 2, a quantum dot light-emitting layer 3, an electron transport layer 4 and a cathode 5; as shown in FIG2 , the material of the electron transport layer 4 may include organic materials and inorganic materials, wherein the inorganic material may include inorganic metal oxide nanoparticles (such as ZnO) and hydroxyl groups (-OH) and solubility groups (M) that modify the inorganic metal oxide nanoparticles (ZnO). In some embodiments, the number of hydroxyl groups (-OH) contained in the electron transport layer 4 is greater than the number of solubility groups (M), and the corresponding treatment process includes but is not limited to performing water vapor treatment on the electron transport layer after preparing the electron transport layer. By adjusting the ventilation volume and / or ventilation time of the water vapor treatment, effective control of the humidity and the number of hydroxyl groups (-OH) contained in the electron transport layer can be achieved. Specifically, in the process of water vapor treatment of the electron transport layer, water is ionized to H + and OH - , OH - Zn adsorbed on ZnO 2+ surface, so that the ethanolamine ligands on the ZnO surface are at least partially replaced by hydroxyl groups (-OH), H + O adsorbed on ZnO 2- Hydroxyl groups (-OH) are formed on the surface, and a certain amount of oxygen elements are consumed to increase the formation of oxygen vacancies, so as to improve the conductivity of the electron transport layer, thereby reducing the turn-on voltage of the light-emitting device. Therefore, the light-emitting device provided by the present invention does not need to undergo an aging process first, and the luminous efficiency of the light-emitting device can also be guaranteed.

[0037] In some embodiments, in the above-mentioned light-emitting device provided in the embodiments of the present disclosure, in order to verify the solubility of the hydroxyl-substituted portion of the surface of the electron transport layer in the embodiments of the present disclosure after water vapor treatment, FIG3 schematically shows the infrared spectrum analysis results of the electron transport layer without water vapor treatment (represented by ZnO) and after water vapor treatment (represented by ZnO water treatment, and with a water vapor content of 30%). It can be seen that after the electron transport layer is water vapor treated, its infrared spectrum at 2750 cm -1 ~3000cm -1 There is no obvious CH vibration peak in the range. This is because the ethanolamine ligand on the ZnO surface is partially replaced by hydroxyl (-OH), which causes the signal of some characteristic peaks to change. For example, the original ZnO at 2800cm -1 The infrared signal peak of CH vibration at will weaken or even disappear after water vapor treatment.

[0038] As shown in FIG4 , infrared spectroscopy analysis was performed on the electron transport layer 4 treated with water vapor under different humidity treatment conditions. It was found that as the humidity increased (for example, the humidity was 0%, 10%, 30%, and 50%), the infrared spectroscopy at 2500 cm -1 ~2700cm-1 The bending vibration absorption peak signal intensity of OH at 3450 cm -1 ~3650cm -1 The stretching vibration absorption peak signal intensity of OH shows a decreasing trend, that is, when the electron transport layer is treated with water vapor and absorbs water molecules, the infrared absorption peak signal at the high wavenumber position will decrease, and the infrared absorption peak signal at the low wavenumber position will increase, which indicates that the number of -OH on the surface of the electron transport layer can be adjusted by treating the electron transport layer with water vapor.

[0039] Furthermore, as shown in FIG4 , in the infrared spectrum of the electron transport layer, for the same infrared spectrum curve (for example, 30% humidity), at 2500 cm -1 ~2700cm -1 The average value of the vertical coordinate of each absorption peak in the range is d1, at 3450cm -1 ~3650cm -1 The average vertical coordinate of each absorption peak in the range is d2, 0.2≤(|d1-d2| / d1)≤0.5, which further illustrates that when the electron transport layer is treated with water vapor at different humidity (for example, increasing humidity), the electron transport layer absorbs water molecules, and the infrared absorption peak signal at the high wavenumber position will decrease, and the infrared absorption peak signal at the low wavenumber position will increase, further indicating that by treating the electron transport layer with water vapor, the amount of -OH on the surface of the electron transport layer can be adjusted to improve the conductivity of the electron transport layer.

[0040] It should be noted that 2800 cm is not shown in Figure 4. -1 ~3300cm -1 In fact, the curves corresponding to the same humidity in high wavenumber and low wavenumber are the same curve.

[0041] In some embodiments, in the above-mentioned light-emitting device provided in the embodiments of the present disclosure, in order to further verify the solubility groups of the hydroxyl-substituted part on the surface of the electron transport layer in the embodiments of the present disclosure after water vapor treatment, Figure 5 schematically shows the X-ray photoelectron spectroscopy results of the electron transport layer without water vapor treatment (represented by ZnO) and with water vapor treatment (represented by ZnO water treatment, and the water vapor content is 30%). It can be seen that the N1s of the electron transport layer after water vapor treatment has no obvious characteristic peaks at 399.5eV and 402eV, which indicates that the ethanolamine ligands on the ZnO surface of the electron transport layer after water vapor treatment will be replaced by a large number of hydroxyl groups (-OH).

[0042] In some embodiments, in the above-mentioned light-emitting device provided by the embodiments of the present disclosure, in order to further verify the solubility group of the hydroxyl-substituted portion on the surface of the electron transport layer in the embodiments of the present disclosure after water vapor treatment, as shown in Figure 6, Figure 6 schematically shows the X-ray photoelectron spectrum of the electron transport layer without water vapor treatment (represented by ZnO) and with water vapor treatment (represented by ZnO water treatment, and the water vapor content is 30%). In the X-ray photoelectron spectrum analysis of the electron transport layer, it can be seen that the Zn 2p of the electron transport layer without water vapor treatment has an obvious characteristic peak at 1020-1022.5eV, and the Zn 2p of the electron transport layer after water vapor treatment has an obvious characteristic peak at 1022.5-1025eV, that is, after the electron transport layer is water vapor treated, the Zn 2p characteristic peak moves toward higher energy (for example, from 1022eV to 1023eV).

[0043] In some embodiments, in the above-mentioned light-emitting device provided by the embodiment of the present disclosure, as shown in FIG2 , the solubility group (M) may include but is not limited to ethanolamine. The embodiment of the present disclosure takes the solubility group (M) as ethanolamine as an example.

[0044] It should be noted that FIG2 is only a schematic illustration of the fact that the number of hydroxyl groups is greater than the number of ethanolamine ligands.

[0045] In the related art, when making a quantum dot light-emitting layer, the material of the quantum dot light-emitting layer includes quantum dot bodies (QDs) and ligands (-X) coordinated and connected to the surface of the quantum dot bodies (QDs). The ligands (-X) are, for example, oleic acid, oleylamine, thiol, etc. However, the carbon chain lengths of ligands such as oleic acid, oleylamine, and thiol are relatively long, resulting in larger spacing between the quantum dot bodies (QDs), causing poor conductivity of the quantum dot light-emitting layer. Therefore, it is necessary to first apply a voltage to the light-emitting device to perform an electrical aging process in order to reduce the turn-on voltage of the light-emitting device and improve the luminous efficiency of the light-emitting device.

[0046] In some embodiments, in the above-mentioned light-emitting device provided in the embodiment of the present disclosure, as shown in FIG7 , the material of the quantum dot light-emitting layer includes a quantum dot body (QD) and a hydroxyl group (-OH) and a ligand (-X) coordinated and connected to the surface of the quantum dot body (QD), and the number of hydroxyl groups (-OH) is greater than the number of ligands (-X). In this way, after preparing the quantum dot light-emitting layer, the present disclosure performs a water vapor treatment on the quantum dot light-emitting layer, so that the ligand (such as oleic acid) on the surface of the quantum dot body (QD) can fall off to form oleic acid molecules under the action of water molecules, and at the same time, the -OH in the water is connected to the surface of the quantum dot body (QD) to fill the defect position. In this way, the length of the ligand on the surface of the quantum dot body (QD) is reduced as a whole, which can reduce the spacing between the quantum dot bodies (QD), increase the conductivity of the quantum dot light-emitting layer, and reduce the light-emitting device start-up voltage. Therefore, the light-emitting device provided by the present disclosure does not need to undergo an aging process first, thereby improving the efficiency of the light-emitting device.

[0047] In some embodiments, in the above-mentioned light-emitting device provided in the embodiment of the present disclosure, as shown in FIG7 , the ligand (-X) may include but is not limited to at least one of oleic acid, oleylamine, and thiol. The embodiment of the present disclosure takes oleic acid as an example of the ligand (-X).

[0048] It should be noted that FIG7 is only a schematic illustration that the number of hydroxyl groups is greater than the number of oleic acid ligands.

[0049] It should be noted that the embodiment of the present disclosure performs water vapor treatment on the electron transport layer and the quantum dot light-emitting layer to improve the conductivity of the electron transport layer and the quantum dot light-emitting layer. Of course, similar to the effect of water vapor treatment, some proton alcohol substances also have similar effects, such as ethanol, propanol, DMF, etc.

[0050] In one possible implementation, the light-emitting device provided in the embodiment of the present disclosure, as shown in FIG1 , further includes a hole injection layer 6 located between the anode 1 and the hole transport layer 2. The hole injection layer 6 performs a hole injection function. Optionally, the material of the hole injection layer may be, but is not limited to, PEDOT:PSS.

[0051] Optionally, the material of the hole transport layer can be at least one of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), poly N-vinylcarbazole (PVK) and poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly-TPD).

[0052] Optionally, the material of the electron transport layer may be, but is not limited to, ZnO or ZnMgO.

[0053] Optionally, the quantum dot body includes any one of: group IIB-VIA quantum dots, group IIIA-VA quantum dots, group IVA-VIA quantum dots, core-shell quantum dots and ABX3 type perovskite quantum dots. In the ABX3 type perovskite quantum dots, A is CH3NH3 + (methylamine), NH2CH=NH2(formamidine) and Cs + One or more of, B is Pb 2+ and Sn 2+ One or two of the following, X is Cl - Br - and I - One or more of the ABX3 type perovskite quantum dots include CH3NH3PbBr3, CH3NH3PbCl3, CH3NH3PbI3, CsPbBr3, CsPbCl3 and CsPbI3.

[0054] Exemplarily, the IIB-VIA group quantum dots are selected from: binary compounds such as one or more of CdSe, CdTe, ZnS, ZnSe, ZnTe, ZnO, HgS, HgSe, HgTe, MgSe, and MgS; ternary compounds such as CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeTe, HgSTe, CdZnS, CdZnSe, CdZn Te, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, MgZnSe, MgZnS, or mixtures thereof; and quaternary compounds such as HgZnTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSTe, HgZnSeS, HgZnSeTe, HgZnSTe, or mixtures thereof, but are not limited thereto.

[0055] The IIIA-VA group quantum dots are selected from: binary compounds such as GaN, GaP, GaAs, GaSb, AlN, AlP, AlAs, AlSb, InN, InP, InAs, InSb, or mixtures thereof; ternary compounds such as GaNPs, GaNAs, GaNSb, GaPAs, GaPSb, AlNPs, AlNAs, AlNSb, AlPAs, AlPSb, InNPs, InNAs, InNSb, InPAs, InPSb, or mixtures thereof; and quaternary compounds such as GaAlNPs, GaAlNAs, GaAlNSb, GaAlPAs, GaAlPSb, GaInNPs, GaInNAs, GaInNSb, GaInPAs, GaInPSb, InAlNPs, InAlNAs, InAlNSb, InAlPAs, InAlPSb, or mixtures thereof, but are not limited thereto.

[0056] Group IVA-VIA quantum dots are selected from, but are not limited to, binary compounds such as SnS, SnSe, SnTe, PbS, PbSe, PbTe, or mixtures thereof; ternary compounds such as SnSeS, SnSeTe, SnSTe, PbSeS, PbSeTe, PbSTe, SnPbS, SnPbSe, SnPbTe, or mixtures thereof; and quaternary compounds such as SnPbSSe, SnPbSeTe, SnPbSTe, or mixtures thereof. Group IVA-VIA quantum dots are selected, for example, from elemental (mono) semiconductors such as Si, Ge, or mixtures thereof; and binary semiconductor compounds such as SiC, SiGe, and mixtures thereof.

[0057] Core-shell quantum dots are structures where one material is the core and the other is the shell. For example, a CdS / ZnS quantum dot is a quantum dot where the core is CdS and the shell is ZnS.

[0058] In some other embodiments, the quantum dot bodies may be other nanoscale materials, such as nanorods, nanosheets, etc. The components of other nanoscale materials may include at least one of CdS, CdSe, CdTe, ZnSe, InP, PbS, CuInS2, ZnO, CsPbCl3, CsPbBr3, CsPhI3, CdS / ZnS, CdSe / ZnS, ZnSe, InP / ZnS, PbS / ZnS, InAs, InGaAs, InGaN, GaNk, ZnTe, Si, Ge, and C.

[0059] For example, the quantum dot body can include cadmium (Cd)-free quantum dots. Cadmium-free quantum dots are quantum dots that do not include cadmium (Cd). Cadmium (Cd) can cause serious environmental / health problems, so non-cadmium-based quantum dots can be effectively used.

[0060] The shapes of quantum dot materials include, but are not limited to, spherical, spherical, ellipsoidal, polyhedral, rod-shaped, cross-shaped, ring-shaped, and other quantum dot materials of any geometric shape.

[0061] Optionally, the light-emitting device provided by the present disclosure may be a quantum dot light-emitting diode, a photodetector, a photovoltaic solar cell, etc., but is not limited thereto.

[0062] Optionally, the light-emitting device provided by the present disclosure may be a quantum dot light-emitting diode, as shown in FIG1 . Optionally, the structure of the quantum dot light-emitting diode provided in the embodiment of the present disclosure may be the upright structure shown in FIG1 , wherein the upright structure is to sequentially fabricate an anode 1, a hole injection layer 6, a hole transport layer 2, a quantum dot light-emitting layer 3, an electron transport layer 4, and a cathode 5 on a substrate 7; the structure of the quantum dot light-emitting diode provided in the embodiment of the present disclosure may also be the inverted structure shown in FIG8 , wherein the inverted structure is to sequentially fabricate a cathode 5, an electron transport layer 4, a quantum dot light-emitting layer 3, a hole transport layer 2, a hole injection layer 6, and an anode 1 on a substrate 7.

[0063] Optionally, the light emitting type of the quantum dot light emitting diode may be a top light emitting structure, a bottom light emitting structure, or a double-sided light emitting structure.

[0064] Based on the same inventive concept, the present disclosure also provides a method for manufacturing a light-emitting device, which is used to manufacture the light-emitting devices shown in Figures 1 and 8 provided in the present disclosure. The manufacturing method includes manufacturing a stacked anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and a cathode; wherein,

[0065] The material of the electron transport layer includes inorganic metal oxide nanoparticles and hydroxyl groups and solubility groups which modify the inorganic metal oxide nanoparticles, wherein the number of the hydroxyl groups is greater than the number of the solubility groups.

[0066] In some embodiments, in the above-mentioned manufacturing method provided in the embodiments of the present disclosure, manufacturing the electron transport layer 4 shown in FIG1 may specifically include:

[0067] forming an electron transport layer 4 on the quantum dot light-emitting layer 3;

[0068] The device having the electron transport layer 4 is treated with water vapor or proton alcohol substances so that the number of hydroxyl groups (-OH) on the surface of the inorganic metal oxide nanoparticles (such as ZnO) is greater than the number of solubility groups (M). The infrared spectrum of the electron transport layer is at 2750 cm -1 ~3000cm-1 There is no obvious CH vibration peak in the range.

[0069] In some embodiments, in the above-mentioned manufacturing method provided in the embodiments of the present disclosure, manufacturing the electron transport layer 4 shown in FIG8 may specifically include:

[0070] forming an electron transport layer 4 on the cathode 5;

[0071] The device having the electron transport layer 4 is subjected to water vapor treatment so that the number of hydroxyl groups (-OH) on the surface of the inorganic metal oxide nanoparticles (such as ZnO) is greater than the number of solubility groups (M); wherein the water vapor content during the water vapor treatment is 30% to 50%.

[0072] The following compares the comparative example (light-emitting device without water vapor treatment) and Examples 1-3 (light-emitting devices of the present disclosure that have been water vapor treated respectively) to illustrate that the luminous efficiency of the light-emitting device of the present disclosure is increased after water vapor treatment.

[0073] Comparative Example: Taking the light emitting device with an upright structure shown in FIG1 as an example, the specific manufacturing process is as follows:

[0074] (1) Depositing an anode on a substrate, which can be glass or a flexible PET substrate. The anode material can be transparent ITO, FTO or a conductive polymer, or it can be an opaque metal electrode such as Al or Ag.

[0075] (2) Depositing a hole injection layer on the anode by spin coating or magnetron sputtering. The material of the hole injection layer can be PEDOT:PSS, MoOx, NiOx, WOx, VOx, etc. The thickness of the hole injection layer is between 20nm and 100nm.

[0076] (3) Depositing a hole transport layer (such as TFB) on the hole injection layer.

[0077] (4) A quantum dot light-emitting layer is deposited on the hole transport layer, and the thickness can be 20nm-50nm.

[0078] (5) An electron transport layer is deposited on the quantum dot light-emitting layer, wherein the material of the electron transport layer is ZnO or ZnMgO nanoparticles.

[0079] (6) A cathode is deposited on the electron transport layer. The cathode material can be metal Al, Ag, etc., or IZO can be deposited by magnetron sputtering. The thickness can be 10-100 nm.

[0080] Example 1: Taking the light emitting device with an upright structure shown in FIG1 as an example, the specific manufacturing process is as follows:

[0081] (1) Depositing an anode on a substrate, which can be glass or a flexible PET substrate. The anode material can be transparent ITO, FTO or a conductive polymer, or it can be an opaque metal electrode such as Al or Ag.

[0082] (2) Depositing a hole injection layer on the anode by spin coating or magnetron sputtering. The material of the hole injection layer can be PEDOT:PSS, MoOx, NiOx, WOx, VOx, etc. The thickness of the hole injection layer is between 20nm and 100nm.

[0083] (3) Depositing a hole transport layer (such as TFB) on the hole injection layer.

[0084] (4) depositing a quantum dot light-emitting layer on the hole transport layer, with a thickness of 20 nm to 50 nm; and then treating with water vapor for 30 minutes (the partial pressure of water is 50 kPa, i.e., 50% humidity).

[0085] (5) Depositing an electron transport layer on the quantum dot light-emitting layer, wherein the material of the electron transport layer is ZnO or ZnMgO nanoparticles.

[0086] (6) A cathode is deposited on the electron transport layer. The cathode material can be metal Al, Ag, etc., or IZO can be deposited by magnetron sputtering. The thickness can be 10-100 nm.

[0087] Example 2: Taking the light emitting device with an upright structure shown in FIG1 as an example, the specific manufacturing process is as follows:

[0088] (1) Depositing an anode on a substrate, which can be glass or a flexible PET substrate. The anode material can be transparent ITO, FTO or a conductive polymer, or it can be an opaque metal electrode such as Al or Ag.

[0089] (2) Depositing a hole injection layer on the anode by spin coating or magnetron sputtering. The material of the hole injection layer can be PEDOT:PSS, MoOx, NiOx, WOx, VOx, etc. The thickness of the hole injection layer is between 20nm and 100nm.

[0090] (3) Depositing a hole transport layer (such as TFB) on the hole injection layer.

[0091] (4) A quantum dot light-emitting layer is deposited on the hole transport layer, and the thickness can be 20nm-50nm.

[0092] (5) depositing an electron transport layer on the quantum dot light-emitting layer, wherein the material of the electron transport layer is ZnO or ZnMgO nanoparticles; and then treating with water vapor for 30 minutes (the partial pressure of water is 50 kPa, i.e., 50% humidity).

[0093] (6) A cathode is deposited on the electron transport layer. The cathode material can be metal Al, Ag, etc., or IZO can be deposited by magnetron sputtering. The thickness can be 10-100 nm.

[0094] Example 3: Taking the light emitting device with an upright structure shown in FIG1 as an example, the specific manufacturing process is as follows:

[0095] (1) Depositing an anode on a substrate, which can be glass or a flexible PET substrate. The anode material can be transparent ITO, FTO or a conductive polymer, or it can be an opaque metal electrode such as Al or Ag.

[0096] (2) Depositing a hole injection layer on the anode by spin coating or magnetron sputtering. The material of the hole injection layer can be PEDOT:PSS, MoOx, NiOx, WOx, VOx, etc. The thickness of the hole injection layer is between 20nm and 100nm.

[0097] (3) Depositing a hole transport layer (such as TFB) on the hole injection layer.

[0098] (4) A quantum dot light-emitting layer is deposited on the hole transport layer, and the thickness can be 20nm-50nm.

[0099] (5) depositing an electron transport layer on the quantum dot light-emitting layer, wherein the material of the electron transport layer is ZnO or ZnMgO nanoparticles; and then treating with water vapor for 30 minutes (the partial pressure of water is 30 kPa, i.e., 30% humidity).

[0100] (6) A cathode is deposited on the electron transport layer. The cathode material can be metal Al, Ag, etc., or IZO can be deposited by magnetron sputtering. The thickness can be 10-100 nm.

[0101] As shown in Figures 9 and 10, Figure 9 is a current density-voltage (IV) relationship diagram corresponding to the light-emitting devices of the comparative example and Examples 1-3, respectively, and Figure 10 is a current efficiency-brightness relationship diagram corresponding to the light-emitting devices of the comparative example and Examples 1-3, respectively. It can be seen from the comparison between the comparative example and the embodiment that the efficiency of the light-emitting device after the electron transport layer and the quantum dot light-emitting layer are treated with water vapor is higher than the efficiency of the light-emitting device after the electron transport layer and the quantum dot light-emitting layer are not treated with water vapor. The current density and current efficiency of Examples 1-3 are both increased, indicating that after water vapor treatment, the conductivity of the quantum dot light-emitting layer increases. The possible reason is that the ligands on the QD surface are replaced by short-chain -OH and the conductivity increases. It can be seen from Example 1 compared with Example 2 and Example 3 that the efficiency of the light-emitting device after the electron transport layer is treated with water vapor is higher than the efficiency of the light-emitting device after the quantum dot light-emitting layer is treated with water vapor. Comparing Example 2 and Example 3, it can be seen that when different humidity treatments are applied to the electron transport layer, the current density increases with increasing humidity, indicating that the conductivity of the electron transport layer increases after water vapor treatment. The possible reason is that the solubility groups on the ZnO surface are replaced by -OH, the O vacancies in ZnO increase, and the conductivity increases. However, if the humidity is too high (for example, 50% humidity in Example 2), the humidity affects the stability of the hole transport layer, or the electron transport layer may partially dissolve, destroying the stability of the entire device and causing a decrease in the current efficiency of the light-emitting device. Therefore, the embodiment of the present disclosure can use the 30% humidity in Example 3 to water vapor treat the electron transport layer, which can improve the efficiency of the light-emitting device.

[0102] Based on the same inventive concept, the embodiments of the present disclosure further provide a display device, including the above-mentioned light-emitting device provided in the embodiments of the present disclosure. The principle of solving the problem of the display device is similar to that of the above-mentioned light-emitting device. Therefore, the implementation of the display device can refer to the implementation of the above-mentioned light-emitting device, and the repeated parts will not be repeated here. The display device can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a laptop computer, a digital photo frame, a navigator, etc. The other essential components of the display device should be understood by ordinary technicians in this field and will not be repeated here, nor should they be used to limit the present disclosure.

[0103] The present disclosure provides a light-emitting device, a method for manufacturing the same, and a display device. Since the number of hydroxyl groups (-OH) on the surface of inorganic metal oxide nanoparticles (ZnO) is greater than the number of solubility groups (such as ethanolamine ligands), this indicates that after the electron transport layer is prepared, the electron transport layer is subjected to water vapor treatment, and water is ionized into H + and OH - , OH - Zn adsorbed on ZnO 2+surface, so that the ethanolamine ligands on the ZnO surface are at least partially replaced by hydroxyl groups (OH), H + O adsorbed on ZnO 2- Hydroxyl groups (-OH) are formed on the surface, consuming oxygen, increasing oxygen vacancies, and increasing the conductivity of the electron transport layer, thereby reducing the turn-on voltage of the light-emitting device. Therefore, the light-emitting device provided by the present disclosure does not need to undergo an aging process first, thereby improving the efficiency of the light-emitting device; and, in the infrared spectrum analysis of the electron transport layer, the present disclosure found that as the humidity increases (for example, the humidity is 0%, 10%, 30%, and 50%), the infrared spectrum at 2400cm -1 ~2600 cm -1 The bending vibration absorption peak signal intensity of OH at 3400 cm -1 ~3600cm -1 The stretching vibration absorption peak signal intensity of OH shows a decreasing trend, that is, when the electron transport layer is treated with water vapor and absorbs water molecules, the infrared absorption peak signal at the high wavenumber position will decrease, and the infrared absorption peak signal at the low wavenumber position will be enhanced, which indicates that the electron transport layer provided in the embodiment of the present disclosure has been treated with water vapor.

[0104] Although the preferred embodiments of the present disclosure have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present disclosure.

[0105] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present disclosure without departing from the spirit and scope of the embodiments of the present disclosure. Thus, if such changes and modifications of the embodiments of the present disclosure fall within the scope of the claims of the present disclosure and their equivalents, the present disclosure is intended to include such changes and modifications.

Claims

1. A light emitting device, wherein: The invention comprises a stacked anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a cathode, wherein the material of the electron transport layer comprises inorganic metal oxide nanoparticles and hydroxyl groups and solubility groups that modify the inorganic metal oxide nanoparticles, wherein the number of the hydroxyl groups is greater than the number of the solubility groups; the infrared spectrum of the electron transport layer is 2750cm -1 ~3000cm -1 There is no obvious CH vibration peak in the range.

2. The light emitting device according to claim 1, wherein In the infrared spectrum of the electron transport layer, for the same infrared spectrum curve, at 2500cm -1 ~2700cm -1 The average value of the vertical coordinate of each absorption peak in the range is d1, at 3450cm -1 ~3650cm -1 The average value of the vertical coordinates of each absorption peak in the range is d2, 0.2≤(|d1-d2| / d1)≤0.

5.

3. The light emitting device according to claim 1, wherein In the X-ray photoelectron spectroscopy analysis of the electron transport layer, N1s has no obvious characteristic peaks at 399.5 eV and 402 eV.

4. The light emitting device according to claim 1, wherein In the X-ray photoelectron spectroscopy analysis of the electron transport layer, Zn 2p has an obvious characteristic peak at 1022.5-1025 eV.

5. The light emitting device according to any one of claims 1 to 4, wherein: The solubilizing group includes ethanolamine.

6. The light emitting device according to any one of claims 1 to 5, wherein: The material of the quantum dot light-emitting layer includes a quantum dot body and hydroxyl groups and ligands coordinated and connected to the surface of the quantum dot body, and the number of the hydroxyl groups is greater than the number of the ligands.

7. The light emitting device according to claim 6, wherein The ligand includes at least one of oleic acid, oleylamine, and thiol.

8. A display device, wherein: The light-emitting device comprises the light-emitting device according to any one of claims 1 to 7.

9. A method for manufacturing a light-emitting device, for manufacturing the light-emitting device according to any one of claims 1 to 7, wherein: The manufacturing method includes manufacturing a stacked anode, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer and a cathode; wherein, The material of the electron transport layer includes inorganic metal oxide nanoparticles and modified inorganic The hydroxyl groups and solubility groups of the metal oxide nanoparticles, the number of the hydroxyl groups is greater than the number of the solubility groups, and the infrared spectrum of the electron transport layer is at 2750cm -1 ~3000cm -1 There is no obvious CH vibration peak in the range.

10. The production method according to claim 9, wherein: The process of making the electron transport layer specifically includes: forming an electron transport layer on the quantum dot light-emitting layer or the cathode; The device having the electron transport layer is subjected to water vapor treatment so that the number of the hydroxyl groups on the surface of the inorganic metal oxide nanoparticles is greater than the number of the solubility groups; wherein the water vapor content during the water vapor treatment is 30% to 50%.

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