Composite material, method for producing the same, and quantum dot light emitting diode

Abstract

The application discloses a composite material, a preparation method thereof and a quantum dot light emitting diode. The composite material comprises MoO3 nanomaterial and an organic compound, the organic compound is a fused ring hydrocarbon or a derivative thereof, molybdenum atoms in the MoO3 nanomaterial are combined with carbon atoms in the organic compound, oxygen atoms in the MoO3 nanomaterial are combined with hydrogen atoms in the organic compound, and a LUMO energy level of the MoO3 nanomaterial is lower than a LUMO energy level of the organic compound. In the application, since the LUMO energy level of MoO3 is lower than a HOMO orbital energy level of the fused ring hydrocarbon or the derivative thereof, electrons on the HOMO energy level of the fused ring hydrocarbon or the derivative thereof are easily transferred to the LUMO energy level of MoO3 to form free holes, so that the hole transport performance is improved, and the light emitting efficiency of the quantum dot light emitting diode is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of quantum dot light emitting devices, and in particular to a composite material, a preparation method thereof and a quantum dot light emitting diode. BACKGROUND

[0002] Quantum dots (QDs) have quantum size effect, and people can realize the light emission of specific wavelength by adjusting the size of quantum dots. The light emission wavelength of CdSe QDs can be tuned from blue light to red light. In a traditional inorganic electroluminescent device, electrons and holes are injected from a cathode and an anode respectively, and then recombine in a light emitting layer to form exciton light. SUMMARY

[0003] The inventors have found that in recent years, P-type organic semiconductor materials and inorganic semiconductor materials as hole transport layers have become a hot research topic. Among them, transition metal oxides (such as WO3, MoO3, NiO, Cu2O and V2O5) are used as anode buffer layers in many quantum dot light emitting diodes and have achieved good performance. In particular, molybdenum oxide has a very deep electronic energy level state and effective hole injection, and has achieved some results. As a transition metal material, molybdenum oxide has attracted extensive attention from researchers at home and abroad due to its unique microstructure, adjustable energy band gap and high carrier mobility. The condensed aromatic hydrocarbon or its derivative formed by linear arrangement of benzene rings has relatively stable properties and hole mobility comparable to amorphous silicon. The hole mobility of the single crystal field effect transistor device prepared therefrom is relatively high and can be comparable to amorphous silicon. However, there are few reports on condensed aromatic hydrocarbons or their derivatives doped with MoO3 nanomaterials.

[0004] Therefore, according to a first aspect of the present application, a composite material is provided, wherein the composite material comprises MoO3 nanomaterial and an organic compound,

[0005] The organic compound is a condensed aromatic hydrocarbon or a derivative thereof,

[0006] The molybdenum atoms in the MoO3 nanomaterial are combined with the carbon atoms in the organic compound, and the oxygen atoms in the MoO3 nanomaterial are combined with the hydrogen atoms in the organic compound,

[0007] The LUMO energy level of the MoO3 nanomaterial is lower than the LUMO energy level of the organic compound.

[0008] According to a second aspect of the present application, a preparation method of the composite material is provided, comprising the following steps:

[0009] The organic compound and the MoO3 nanomaterial are dissolved in an alcohol solvent to perform a first hydrothermal reaction, so as to obtain a composite material in which the organic compound is combined with the MoO3 nanomaterial.

[0010] According to a third aspect of the present application, a quantum dot light emitting diode is provided, comprising a hole transport layer, wherein the hole transport layer comprises the composite material according to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 A structure schematic diagram of a quantum dot light emitting diode provided in an embodiment of the present application.

[0012] Figure 2 A structure schematic diagram of a quantum dot light emitting diode provided in an embodiment of the present application.

[0013] Figure 3 A flowchart of a preparation method of a quantum dot light emitting diode provided in an embodiment of the present application. DETAILED DESCRIPTION

[0014] The present application provides a composite material, a preparation method thereof and a quantum dot light emitting diode. In order to make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0015] The present application provides a composite material, a preparation method thereof and a quantum dot light emitting diode. In order to make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0016] The organic compound is a fused ring hydrocarbon or a derivative thereof.

[0017] The molybdenum atoms in the MoO3 nanomaterial are combined with the carbon atoms in the organic compound, and the oxygen atoms in the MoO3 nanomaterial are combined with the hydrogen atoms in the organic compound.

[0018] The LUMO energy level of the MoO3 nanomaterial is lower than the LUMO energy level of the organic compound.

[0019] In the embodiment of the present application, when the fused ring hydrocarbon or its derivative is combined with MoO3, the metal atom Mo is combined with the C atom on the fused ring hydrocarbon or its derivative, and meanwhile, the O atom is combined with the H atom on the fused ring hydrocarbon or its derivative to form a bond. When the composite material is applied to a quantum dot light emitting diode as a hole transport material, because the LUMO energy level of MoO3 is lower than the HOMO orbital energy level of the fused ring hydrocarbon or its derivative, the electron on the HOMO energy level of the fused ring hydrocarbon or its derivative is easily transferred to the LUMO energy level of MoO3, which is equivalent to forming an impurity energy level close to the HOMO energy level in the band gap of the fused ring hydrocarbon or its derivative, and the electron on the HOMO energy level of the fused ring hydrocarbon or its derivative is easily transferred to the acceptor energy level, thereby forming a free hole, so that the hole transport performance is improved, and the light emitting efficiency of the quantum dot light emitting diode is further improved.

[0020] In an embodiment, the organic compound is pentacene, and the pentacene is unsubstituted pentacene or substituted pentacene. In an embodiment, the composite material is composed of pentacene and MoO3 nanomaterial combined with the pentacene.

[0021] Pentacene is a fused ring aromatic hydrocarbon linearly arranged by five benzene rings, and has relatively stable properties and a hole mobility comparable to amorphous silicon. The hole mobility of a field effect transistor device prepared from a single crystal of pentacene can reach 15-40 cm 2 / V·s, which is comparable to amorphous silicon.

[0022] In the embodiment of the present application, when pentacene is combined with MoO3, the metal atom Mo is combined with the C atom on the pentacene, and meanwhile, the O atom is combined with the H atom on the pentacene to form a bond. When the composite material is applied to a quantum dot light emitting diode as a hole transport material, for pentacene, the HOMO energy level is -4.9 eV, and the LUMO energy level of MoO3 is -6.5 eV. Because the LUMO energy level of MoO3 is significantly lower than the HOMO orbital energy level of pentacene, about -1.6 eV, the electron on the HOMO energy level of pentacene is easily transferred to the LUMO energy level of MoO3, which is equivalent to forming an impurity energy level close to the HOMO energy level in the band gap of pentacene, and the electron on the HOMO energy level of pentacene is easily transferred to the acceptor energy level, thereby forming a free hole, so that the hole transport performance is improved, and the light emitting efficiency of the quantum dot light emitting diode is further improved.

[0023] In an embodiment, the pentacene is a substituted pentacene, which is an electron-withdrawing group substituted pentacene. The electron-withdrawing group connected to the pentacene can lower the HOMO energy level of the pentacene, which is conducive to the electron transfer to the LUMO energy level of MoO3 to form more free holes. In an embodiment, the electron-withdrawing group is one or more of the commonly used electron-withdrawing groups such as -F, -Br, -Cl, -CN and -NO3, and the substitution position of the electron-withdrawing group on the pentacene is not limited.

[0024] In an embodiment, the molar ratio of the organic compound (such as pentacene) to MoO3 nanomaterial is 1:(0.1-0.3). Taking the molar amount of pentacene as 1 as a reference, when the doping amount of molybdenum oxide is less than 0.1, the pentacene is excessive, the less molybdenum oxide cannot play a doping effect, and the effect of improving the hole transport efficiency is not obvious. When the doping amount of molybdenum oxide is greater than 0.3, the molybdenum oxide is excessive, and the excessive molybdenum oxide reduces the proportion of pentacene, and the effect of improving the hole transport efficiency is also not obvious.

[0025] The embodiment of the present application provides a preparation method of a composite material, which comprises the following steps:

[0026] The organic compound and the MoO3 nanomaterial are dissolved in an alcohol solvent to perform a first hydrothermal reaction, so as to obtain a composite material in which the organic compound is combined with the MoO3 nanomaterial; wherein the organic compound is a fused ring hydrocarbon or a derivative thereof.

[0027] In an embodiment, the organic compound is pentacene, which is unsubstituted pentacene or substituted pentacene.

[0028] In the embodiment of the present application, when the pentacene is combined with MoO3, the metal atom Mo is combined with the C atom on the pentacene, and the O atom is combined with the H atom on the pentacene to form a bond. When the composite material is applied to a quantum dot light emitting diode as a hole transport material, the HOMO energy level of the pentacene is -4.9 eV, and the LUMO energy level of MoO3 is -6.5 eV. Since the LUMO energy level of MoO3 is significantly lower than the HOMO orbital energy level of the pentacene, about -1.6 eV, the electron on the HOMO energy level of the pentacene can be easily transferred to the LUMO energy level of MoO3, which is equivalent to forming an impurity energy level close to the HOMO energy level in the band gap of the pentacene. The electron on the HOMO energy level of the pentacene can be easily transferred to the acceptor energy level, forming a free hole, thereby improving the hole transport performance and further improving the light emitting efficiency of the quantum dot light emitting diode. The inventors have found that it is difficult to apply other transition metal oxides to the embodiment, and therefore MoO3 is selected in the embodiment. In addition, the method for preparing the composite material in which the pentacene is combined with MoO3 in the embodiment of the present application is very simple and suitable for large-area and large-scale preparation.

[0029] In an embodiment, the pentacene is a substituted pentacene, and the substituted pentacene is a pentacene substituted with an electron-withdrawing group. The substitution of the pentacene with the electron-withdrawing group can lower the HOMO energy level of the pentacene, and facilitate the transfer of electrons to the LUMO energy level of MoO3, thereby forming more free holes. In an embodiment, the electron-withdrawing group is one or more of -F, -Br, -Cl, -CN, -NO3, and the like, and the substitution position of the pentacene is not limited.

[0030] In an embodiment, the molar ratio of the organic compound (e.g., pentacene) to the MoO3 nanomaterial is 1:(0.1-0.3). When the doping amount of MoO3 is less than 0.1, the pentacene is in excess, the less MoO3 cannot achieve the doping effect, and the effect of improving the hole transport efficiency is not obvious. When the doping amount of MoO3 is greater than 0.3, the MoO3 is in excess, and the excess MoO3 reduces the proportion of pentacene, and the effect of improving the hole transport efficiency is not obvious.

[0031] In an embodiment of the present application, after the first hydrothermal reaction, the organic compound (e.g., pentacene) and MoO3 combined composite material is obtained, and the method further comprises the steps of cooling, washing, and drying. The drying temperature can be 50-60°C.

[0032] In an embodiment, the temperature of the first hydrothermal reaction is 150-180°C.

[0033] In an embodiment, the time of the first hydrothermal reaction is 18-30h.

[0034] In an embodiment, the method for preparing the MoO3 nanomaterial comprises the steps of:

[0035] The Mo source is dissolved in water, acid is added, and the second hydrothermal reaction is performed to obtain the MoO3 nanomaterial.

[0036] In an embodiment of the present application, the formation process of the MoO3 nanomaterial can be described by the following three chemical reaction equations: (1) MoO4 2- +H + =HMoO4 - ; (2) HMoO4 - +H + =H2MoO4(aq); (3) H2MoO4(aq)=MoO3·H2O. In the hydrothermal reaction process, the more H + in the system, the more conducive to the formation of H2MoO4, and the more MoO3 is obtained. If H +The reaction process tends to be slow, and the reaction time needs to be increased; the increase of the reaction time easily leads to the formation of large MoO3 crystal particles. Therefore, it is better to add acid to pH <1.

[0037] In the embodiment of the present application, before the MoO3 nanomaterial is obtained after the second hydrothermal reaction, the method further comprises the steps of cooling, washing, and drying. The drying temperature can be 50-60℃.

[0038] In an embodiment, the molybdenum source can be one or more of sodium molybdate, amine molybdate, potassium molybdate, and magnesium molybdate, but is not limited thereto.

[0039] In an embodiment, the acid can be one or more of sulfuric acid, nitric acid, and hydrochloric acid, but is not limited thereto.

[0040] In an embodiment, the temperature of the second hydrothermal reaction is 150-220℃.

[0041] In an embodiment, the time of the second hydrothermal reaction is 18-30h.

[0042] The embodiment of the present application provides a quantum dot light emitting diode, comprising a hole transport layer, wherein the hole transport layer comprises the composite material in the embodiment of the present application.

[0043] As shown in Figure 1 The quantum dot light emitting diode in the embodiment of the present application comprises an anode 1, a cathode 4, a quantum dot light emitting layer 3 arranged between the anode 1 and the cathode 4, and a hole transport layer 2 arranged between the anode 1 and the quantum dot light emitting layer 3, wherein the hole transport layer 2 comprises the composite material in the embodiment of the present application, and the composite material comprises a MoO3 nanomaterial and an organic compound,

[0044] The organic compound is a fused ring hydrocarbon or a derivative thereof,

[0045] The molybdenum atoms in the MoO3 nanomaterial are combined with the carbon atoms in the organic compound, and the oxygen atoms in the MoO3 nanomaterial are combined with the hydrogen atoms in the organic compound,

[0046] The LUMO energy level of the MoO3 nanomaterial is lower than the LUMO energy level of the organic compound.

[0047] In an embodiment, the composite material is composed of an organic compound and a MoO3 nanomaterial combined with the organic compound.

[0048] In an embodiment, the organic compound is pentacene, and the pentacene is unsubstituted pentacene or substituted pentacene.

[0049] In the embodiment of the present application, when pentacene is combined with MoO3, the metal atom Mo is combined with the C atom on the pentacene, and the O atom is combined with the H atom on the pentacene to form a bond. For pentacene, the HOMO energy level is -4.9 eV, and the LUMO energy level of MoO3 is -6.5 eV. Since the LUMO energy level of MoO3 is obviously lower than the HOMO orbital energy level of pentacene, about -1.6 eV, the electron on the HOMO energy level of pentacene is easily transferred to the LUMO energy level of MoO3, which is equivalent to forming an impurity energy level close to the HOMO energy level in the band gap of pentacene. The electron on the HOMO energy level of pentacene is easily transferred to the acceptor energy level, forming a free hole, thereby improving the hole transport performance and further improving the light-emitting efficiency of the quantum dot light-emitting diode.

[0050] In the embodiment of the present application, the quantum dot light-emitting diode has various forms, and the quantum dot light-emitting diode is divided into a positive type structure and a reverse type structure. The embodiment of the present application will be described in detail taking the quantum dot light-emitting diode of the positive type structure as shown in Figure 2 Figure 2 As shown in the figure, the quantum dot light-emitting diode comprises, from bottom to top, a substrate 5, an anode 6, a hole transport layer 7, a quantum dot light-emitting layer 8, an electron transport layer 9 and a cathode 10; wherein the hole transport layer 7 comprises a composite material, and the composite material comprises pentacene and MoO3 nanomaterial combined with the pentacene; wherein the pentacene is unsubstituted pentacene or substituted pentacene.

[0051] In an embodiment, in the composite material, the molar ratio of the pentacene and the MoO3 nanomaterial is 1: (0.1-0.3). If the ratio is too small, the effect of improving the hole transport efficiency is not obvious; and if the ratio is too large, it is not conducive to the hole transport.

[0052] In an embodiment, the thickness of the hole transport layer is 20-60 nm. If the thickness of the hole transport layer is too thin, the transport performance of the carrier cannot be guaranteed, which leads to the hole-electron recombination in the transport layer and causes quenching. If the thickness of the hole transport layer is too thick, the light transmittance of the film layer is reduced, and the carrier passing performance of the device is reduced, which leads to the decrease of the overall conductivity of the device.

[0053] In an embodiment, the substrate can be a substrate of rigid material, such as glass, or a substrate of flexible material, such as one of PET or PI.

[0054] In an embodiment, the anode can be selected from one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO) and aluminum-doped zinc oxide (AZO).​

[0055] In an embodiment, the light-emitting quantum dots of the quantum dot light-emitting layer are oil-soluble light-emitting quantum dots, which include binary phase, ternary phase, and quaternary phase quantum dots; the binary phase quantum dots include CdS, CdSe, CdTe, InP, AgS, PbS, PbSe, HgS, and the like, the ternary phase quantum dots include ZnCdS, CuInS, ZnCdSe, ZnSeS, ZnCdTe, PbSeS, and the like, and the quaternary phase quantum dots include ZnCdS / ZnSe, CuInS / ZnS, ZnCdSe / ZnS, CuInSeS, ZnCdTe / ZnS, PbSeS / ZnS, and the like. The light-emitting quantum dots can be selected from one of common red, green, and blue quantum dots, or can be yellow quantum dots. The quantum dots can contain cadmium or not. The quantum dot light-emitting layer has the characteristics of wide and continuous distribution of excitation spectrum and high stability of emission spectrum.

[0056] In an embodiment, the material of the electron transport layer can be selected from materials having good electron transport performance, for example, can be but is not limited to one or more of n-type ZnO, TiO2, Fe2O3, SnO2, Ta2O3, AlZnO, ZnSnO, InSnO, and the like.

[0057] In an embodiment, the cathode can be selected from one of an aluminum (Al) electrode, a silver (Ag) electrode, and a gold (Au) electrode, and can also be selected from one of a nano-aluminum wire, a nano-silver wire, and a nano-gold wire.

[0058] It should be noted that the quantum dot light-emitting diode of the present application can also include one or more of the following functional layers: a hole injection layer disposed between the hole transport layer and the anode, and an electron injection layer disposed between the electron transport layer and the cathode.

[0059] The present application also provides a preparation method of a quantum dot light-emitting diode with a positive structure, as shown in Figure 3 The preparation method includes the following steps:

[0060] S10, forming a hole transport layer on an anode, wherein the hole transport layer includes a composite material, and the composite material includes pentacene and MoO3 nanomaterial combined with the pentacene, and the pentacene is unsubstituted pentacene or substituted pentacene;

[0061] S20, forming a quantum dot light-emitting layer on the hole transport layer;

[0062] S30, forming a cathode on the quantum dot light-emitting layer to obtain the quantum dot light-emitting diode.

[0063] In the embodiment of the present application, the preparation method of the composite material is as described above, and will not be repeated here.

[0064] In step S10, in order to obtain a high-quality hole transport layer, the anode needs to be subjected to a pretreatment process. The pretreatment process specifically includes: cleaning the anode with a cleaning agent to preliminarily remove stains present on the surface of the anode, and then sequentially ultrasonically cleaning in deionized water, acetone, anhydrous ethanol, and deionized water for 20 min, respectively, to remove impurities present on the surface, and finally blowing dry with high-purity nitrogen, to obtain the anode.

[0065] In one embodiment, a preparation method such as drop coating, spin coating, soaking, coating, printing, and evaporation, not limited thereto, can be used to form the hole transport layer on the anode.

[0066] In one embodiment, step S10 specifically includes: spin coating the prepared solution of the hole transport layer material on the anode, and then performing thermal annealing treatment at 300-350°C to obtain the hole transport layer. The film thickness can be controlled by adjusting the concentration of the solution, the spin coating speed, and the spin coating time, and the thickness of the hole transport layer can be 20-60 nm.

[0067] In one embodiment, step S20 specifically includes: placing the substrate on which the hole transport layer has been spin coated on a film uniformizer, spin coating the prepared solution of the luminescent quantum dots on the hole transport layer, and then performing thermal annealing treatment to obtain the quantum dot luminescent layer. The film thickness can be controlled by adjusting the concentration of the solution, the spin coating speed, and the spin coating time, and the thickness of the quantum dot luminescent layer can be 20-60 nm.

[0068] In one embodiment, step S30 specifically includes: placing the substrate on which the functional layers have been deposited in an evaporation chamber to perform thermal evaporation of a 15-30 nm layer of cathode material through a mask plate to obtain the cathode. The cathode material can be metal silver or aluminum, or a nano-Ag wire or Cu wire, which has a small resistance to enable smooth injection of carriers.

[0069] In one embodiment, the obtained quantum dot light-emitting diode is subjected to packaging treatment. The packaging treatment can be machine packaging or manual packaging. Preferably, the oxygen content and water content in the environment of the packaging treatment are both less than 0.1 ppm, to ensure the stability of the device.

[0070] The present application will be described in detail below through specific embodiments.

[0071] Embodiment 1

[0072] 1 g ammonium molybdate was added to 30 ml water, and stirred until completely dissolved. 3 ml of concentrated hydrochloric acid was added, and the pH was <1. The solution was stirred for 30 min. Then it was transferred to a hydrothermal reactor, and reacted at 200°C for 24 h. After cooling, it was washed with water twice and ethanol once, and dried at 50°C to obtain MoO3nanomaterials.

[0073] 1 g pentacene was dissolved in 30 ml ethanol, and 1 g MoO3nanomaterials were added. The molar ratio of pentacene to MoO3nanomaterials was 1:0.1. After stirring for 30 min, the solution was transferred to a hydrothermal reactor, and reacted at 150°C for 24 h. After cooling, it was washed with water twice and ethanol once, and dried at 50°C to obtain a pentacene-MoO3nanocomposite.

[0074] Example 2

[0075] 1 g ammonium molybdate was added to 30 ml water, and stirred until completely dissolved. 3 ml of concentrated nitric acid was added, and the pH was <1. The solution was stirred for 30 min. Then it was transferred to a hydrothermal reactor, and reacted at 200°C for 24 h. After cooling, it was washed with water twice and ethanol once, and dried at 50°C to obtain MoO3nanomaterials.

[0076] 1 g brominated pentacene was dissolved in 30 ml ethanol, and 1 g MoO3nanomaterials were added. The molar ratio of brominated pentacene to MoO3nanomaterials was 1:0.2. After stirring for 30 min, the solution was transferred to a hydrothermal reactor, and reacted at 150°C for 24 h. After cooling, it was washed with water twice and ethanol once, and dried at 50°C to obtain a brominated pentacene-MoO3nanocomposite.

[0077] Example 3

[0078] 1 g ammonium molybdate was added to 30 ml water, and stirred until completely dissolved. 3 ml of concentrated sulfuric acid was added, and the pH was <1. The solution was stirred for 30 min. Then it was transferred to a hydrothermal reactor, and reacted at 200°C for 24 h. After cooling, it was washed with water twice and ethanol once, and dried at 50°C to obtain MoO3nanomaterials.

[0079] 1 g cyanated pentacene was dissolved in 30 ml ethanol, and 1 g MoO3nanomaterials were added. The molar ratio of cyanated pentacene to MoO3nanomaterials was 1:0.2. After stirring for 30 min, the solution was transferred to a hydrothermal reactor, and reacted at 150°C for 24 h. After cooling, it was washed with water twice and ethanol once, and dried at 50°C to obtain a cyanated pentacene-MoO3nanocomposite.

[0080] Example 4

[0081] A quantum dot light emitting diode comprises a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the anode arranged on a substrate. The material of the substrate is a glass sheet, the material of the anode is an ITO substrate, the material of the hole transport layer is a composite material of pentacene combined with MoO3, the material of the electron transport layer is ZnO, and the material of the cathode is Al.

[0082] A preparation method of the quantum dot light emitting diode comprises the following steps:

[0083] An ITO substrate is provided, and a hole transport layer is prepared on the ITO substrate. The material of the hole transport layer is the composite material of pentacene combined with MoO3 obtained in the method of embodiment 1.

[0084] A quantum dot light emitting layer is deposited on the hole transport layer.

[0085] An electron transport layer is deposited on the quantum dot light emitting layer.

[0086] A cathode is prepared on the electron transport layer.

[0087] Embodiment 5

[0088] A quantum dot light emitting diode comprises a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the anode arranged on a substrate. The material of the substrate is a glass sheet, the material of the anode is an ITO substrate, the material of the hole transport layer is a composite material of brominated pentacene combined with MoO3, the material of the electron transport layer is ZnO, and the material of the cathode is Al.

[0089] A preparation method of the quantum dot light emitting diode comprises the following steps:

[0090] An ITO substrate is provided, and a hole transport layer is prepared on the ITO substrate. The material of the hole transport layer is the composite material of brominated pentacene combined with MoO3 obtained in the method of embodiment 2.

[0091] A quantum dot light emitting layer is deposited on the hole transport layer.

[0092] An electron transport layer is deposited on the quantum dot light emitting layer.

[0093] A cathode is prepared on the electron transport layer.

[0094] Embodiment 6

[0095] A quantum dot light emitting diode, comprising a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the anode arranged on a substrate. Wherein, the material of the substrate is a glass sheet, the material of the anode is an ITO substrate, the material of the hole transport layer is a composite material of cyanated pentacene combined with MoO3, the material of the electron transport layer is ZnO, and the material of the cathode is Al.

[0096] A preparation method of the quantum dot light emitting diode, comprising the following steps:

[0097] providing an ITO substrate, and preparing a hole transport layer on the ITO substrate, wherein the material of the hole transport layer is the composite material of cyanated pentacene combined with MoO3 obtained in the method of embodiment 3;

[0098] depositing a quantum dot light emitting layer on the hole transport layer;

[0099] depositing an electron transport layer on the quantum dot light emitting layer;

[0100] preparing a cathode on the electron transport layer.

[0101] Embodiment 7

[0102] A quantum dot light emitting diode, comprising a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the cathode arranged on a substrate. Wherein, the material of the substrate is a glass sheet, the material of the cathode is an ITO substrate, the material of the hole transport layer is a composite material of pentacene combined with MoO3, the material of the electron transport layer is ZnO, and the material of the anode is Al.

[0103] A preparation method of the quantum dot light emitting diode, comprising the following steps:

[0104] providing a cathode substrate, and depositing an electron transport layer on the cathode substrate;

[0105] preparing a quantum dot light emitting layer on the electron transport layer;

[0106] preparing a hole transport layer on the quantum dot light emitting layer, wherein the material of the hole transport layer is the composite material of pentacene combined with MoO3 obtained in the method of embodiment 1;

[0107] preparing an anode on the hole transport layer.

[0108] Embodiment 8

[0109] A quantum dot light emitting diode, comprising a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the cathode arranged on a substrate. Wherein, the material of the substrate is a glass sheet, the material of the cathode is an ITO substrate, the material of the hole transport layer is a composite material of pentacene and MoO3, the material of the electron transport layer is ZnO, and the material of the anode is Al.

[0110] A preparation method of the quantum dot light emitting diode, comprising the following steps:

[0111] providing a cathode substrate, and depositing an electron transport layer on the cathode substrate;

[0112] preparing a quantum dot light emitting layer on the electron transport layer;

[0113] preparing a hole transport layer on the quantum dot light emitting layer, and the material of the hole transport layer is the composite material of pentacene and MoO3 obtained in the method of embodiment 2;

[0114] preparing an anode on the hole transport layer.

[0115] Embodiment 9

[0116] A quantum dot light emitting diode, comprising a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the cathode arranged on a substrate. Wherein, the material of the substrate is a glass sheet, the material of the cathode is an ITO substrate, the material of the hole transport layer is a composite material of pentacene and MoO3, the material of the electron transport layer is ZnO, and the material of the anode is Al.

[0117] A preparation method of the quantum dot light emitting diode, comprising the following steps:

[0118] providing a cathode substrate, and depositing an electron transport layer on the cathode substrate;

[0119] preparing a quantum dot light emitting layer on the electron transport layer;

[0120] preparing a hole transport layer on the quantum dot light emitting layer, and the material of the hole transport layer is the composite material of pentacene and MoO3 obtained in the method of embodiment 3;

[0121] preparing an anode on the hole transport layer.

[0122] Comparative Example 1

[0123] A quantum dot light emitting diode comprises a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the cathode arranged on a substrate. The material of the substrate is a glass sheet, the material of the anode is an ITO substrate, the material of the hole transport layer is a commercial MoO3 material (purchased from sigma company), the material of the electron transport layer is ZnO, and the material of the cathode is Al.

[0124] Comparative Example 2

[0125] A quantum dot light emitting diode comprises a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the cathode arranged on a substrate. The material of the substrate is a glass sheet, the material of the anode is an ITO substrate, the material of the hole transport layer is a commercial pentacene material (purchased from sigma company), the material of the electron transport layer is ZnO, and the material of the cathode is Al.

[0126] Comparative Example 3

[0127] A quantum dot light emitting diode comprises a stack structure of oppositely arranged anode and cathode, a quantum dot light emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the cathode and the quantum dot light emitting layer, a hole transport layer arranged between the anode and the quantum dot light emitting layer, and the cathode arranged on a substrate. The material of the substrate is a glass sheet, the material of the anode is an ITO substrate, the material of the hole transport layer is a composite material of pentacene and nickel oxide, the material of the electron transport layer is ZnO, and the material of the cathode is Al.

[0128] The hole transport thin film composed of the composite material prepared in Comparative Examples 1-3, the hole transport thin film in Comparative Examples 1-3, the quantum dot light emitting diode prepared in Examples 4-9 and Comparative Examples 1-3 are tested for performance, and the test indexes and test methods are as follows:

[0129] (1) Hole mobility: test the current density (J)-voltage (V) of the hole transport thin film, draw the curve relationship graph, fit the space charge limited current (SCLC) region in the relationship graph, and then calculate the hole mobility according to the famous Child’s law formula:

[0130] J=(9 / 8)ε rε0μ e V 2 / d 3

[0131] wherein J represents current density, unit: mAcm -2 ; ε r represents relative dielectric constant, ε0 represents vacuum dielectric constant; μ e represents hole mobility, unit: cm 2 V -1 s -1 ; V represents driving voltage, unit: V; d represents film thickness, unit: m.

[0132] (2) Resistivity: the resistivity of the electron transport thin film was determined by using the same resistivity testing instrument.

[0133] (3) External quantum efficiency (EQE): the EQE optical testing instrument was used for determination.

[0134] Note: The hole mobility and resistivity testing were single-layer thin film structure devices, i.e. cathode / hole transport thin film / anode. The external quantum efficiency testing was the QLED device, i.e. anode / hole transport thin film / quantum dot / electron transport thin film / cathode, or cathode / electron transport thin film / quantum dot / hole transport thin film / anode.

[0135] The test results are shown in Table 1 below:

[0136] Table 1

[0137]

[0138] From Table 1 above, it can be seen that the hole transport thin film made of the pentacene and MoO3 combined composite provided by Examples 1-3 has a significantly lower resistivity than the hole transport thin films made of MoO3 material, pentacene material and pentacene and nickel oxide combined composite in Comparative Examples 1-3, and a significantly higher hole mobility than the hole transport thin films made of MoO3 material, pentacene material and pentacene and nickel oxide combined composite in Comparative Examples 1-3.

[0139] The external quantum efficiency of the quantum dot light emitting diode (the hole transport layer material is the pentacene and MoO3 combined composite) provided by Examples 4-9 is significantly higher than the external quantum efficiency of the quantum dot light emitting diode of MoO3 material, pentacene material and pentacene and nickel oxide combined composite in Comparative Examples 1-3, indicating that the quantum dot light emitting diode obtained by Examples 4-9 has better light emitting efficiency.

[0140] It is worth noting that the specific embodiments provided by the present application are all based on blue quantum dots Cd X Zn 1-XS / ZnS as the light emitting layer material is based on the blue light emitting system which is used more (since it is more difficult to achieve high efficiency for the blue quantum dot light emitting diode, therefore it is more valuable for reference), and does not represent that the application is only used for the blue light emitting system.

[0141] In summary, the application provides a kind of composite material, quantum dot light emitting diode and its preparation method.In the application, when pentacene and MoO3 are combined, metal atom Mo will be combined with C atom on pentacene, and O atom will be combined with H atom on pentacene to form a bond.For pentacene, HOMO energy level is-4.9eV; and LUMO energy level of MoO3 is-6.5eV. Since LUMO energy level of MoO3 is significantly lower than HOMO orbital energy level of pentacene, about-1.6eV, electron on HOMO energy level of pentacene is easy to transfer to LUMO energy level of MoO3, which is equivalent to forming an impurity energy level close to HOMO energy level in the band gap of pentacene, and electron on HOMO energy level of pentacene is easy to transfer to this acceptor energy level to form a free hole, thereby improving the hole transport performance, and further improving the light emitting efficiency of quantum dot light emitting diode.

[0142] It should be understood that the application of the application is not limited to the above examples, and those skilled in the art can improve or change according to the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the application.

Claims

1. A composite material, characterized by, The composite material comprises MoO3 nanomaterial and organic compound, The organic compound is substituted with one or more of -F, -Br, -Cl, -CN and -NO3. The molybdenum atoms in the MoO3 nanomaterial are combined with the carbon atoms in the organic compound, and the oxygen atoms in the MoO3 nanomaterial are combined with the hydrogen atoms in the organic compound. The LUMO energy level of the MoO3 nanomaterial is lower than that of the organic compound.

2. The composite material of claim 1, wherein, The molar ratio of the organic compound to the MoO3 nanomaterial is 1:(0.1-0.3).

3. A method for the production of a composite material according to any one of claims 1 to 2, characterized in that The method comprises the steps of: dissolving a molybdenum source in water, adding an acid, and performing a second hydrothermal reaction to obtain MoO3 nanomaterial; dissolving the organic compound and the MoO3 nanomaterial in an alcohol solvent, performing a first hydrothermal reaction to obtain the composite material of the organic compound combined with the MoO3 nanomaterial.

4. The method of claim 3, wherein the step of applying the coating is performed after the step of applying the first layer of the composite material. The temperature of the first hydrothermal reaction is 150-180℃, and the time of the first hydrothermal reaction is 18-30h.

5. The method of claim 3, wherein the step of applying the coating is performed by a method selected from the group consisting of: spray coating, dip coating, and spin coating. The molybdenum source is one or more of sodium molybdate, amine molybdate, potassium molybdate and magnesium molybdate; The acid is one or more of sulfuric acid, nitric acid and hydrochloric acid; The acid is added to pH<1; The temperature of the second hydrothermal reaction is 150-220℃; The time of the second hydrothermal reaction is 18-30h.

6. A quantum dot light emitting diode comprising a hole transport layer, characterized in that, The hole transport layer comprises the composite material of any one of claims 1-2.

7. The quantum dot light emitting diode of claim 6, wherein the quantum dot light emitting diode is a quantum dot light emitting diode on silicon. The hole transport layer is composed of MoO3 nanomaterial and organic compound.

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