Quantum Dot Light-Emitting Device and Method for Preparing the Same

Abstract

The present invention relates to the technical field of quantum dot light-emitting devices. Specifically, it relates to a quantum dot light-emitting device and a preparation method thereof. The quantum dot light-emitting device includes an ITO substrate, a hole injection layer, a fluoropolymer layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer that are sequentially stacked. In the present invention, a fluoropolymer layer is provided between the hole injection layer and the hole transport layer, and the obtained quantum dot light-emitting device can promote the injection of holes, improve the recombination rate of electron-hole pairs, and enhance the device performance.

Description

Technical Field

[0001] The present invention relates to the technical field of quantum dot light-emitting devices, and more particularly, to a quantum dot light-emitting device and a method for preparing the same. Background Art

[0002] Quantum dots have been widely used in many aspects such as light-emitting diodes, solar cells, bioimaging, detectors, etc. Among them, quantum dot light-emitting diodes (QLEDs) have become a favorable competitor for the next-generation display technology due to their advantages such as high color purity, tunable emission color, and good stability. Currently, the carrier injection imbalance in quantum dot light-emitting diodes limits their luminous efficiency and lifespan. The common structure of a quantum dot light-emitting diode is an electron transport layer, a hole transport layer, and a quantum dot light-emitting layer. These hole transport layers and electron transport layers can be organic small molecules, organic polymers, or inorganic metal oxides. The setting of the above electron transport layer and hole transport layer has increased the luminous efficiency of the light-emitting diode device from less than 0.01% at the beginning to 10%. However, due to the problem of mismatched energy level structures, the hole injection efficiency is generally lower than the electron injection efficiency, resulting in an imbalance in the injected charges in the quantum dots and the quantum dots being non-electrically neutral. Coupled with the influence of the applied electric field, the intrinsic luminous efficiency of the quantum dots is greatly reduced. Another problem is that due to the work function difference between the quantum dots and the electron transport layer, there is a spontaneous charge transfer phenomenon, which destroys the electrical neutrality of the quantum dot layer and leads to a reduction in the luminous efficiency.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] An object of the present invention is to provide a quantum dot light-emitting device to solve the technical problem of low luminous efficiency of quantum dot light-emitting devices in the prior art.

[0005] Another object of the present invention is to provide a method for preparing the quantum dot light-emitting device, which can promote hole injection, improve the recombination rate of electron-hole pairs, and enhance device performance.

[0006] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0007] A quantum dot light-emitting device includes an ITO substrate, a hole injection layer, a fluoropolymer layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer, which are sequentially stacked.

[0008] In one embodiment, the fluoropolymer layer includes at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, and polyperfluoroethylpropylene.

[0009] In one embodiment, the thickness of the fluoropolymer layer is 70-100 nm.

[0010] In one embodiment, the hole transport layer includes at least one of TFB, PVK, TCTA, TPD, Poly:TPD, and CBP.

[0011] In one embodiment, the electron transport layer includes at least one of ZnO, TiO2, SnO2, and Alq3.

[0012] In one embodiment, the hole injection layer includes at least one of PEDOT:PSS, PTPDES, PTPDES:TPBAH, PFO-co-NEPBN, PFO-co-NEPBN:F4-TCNQ, MoO2, MoO3, WO2, WO3, NiO, and CuO.

[0013] In one embodiment, in the quantum dot light-emitting layer, the quantum dots include at least one of II-VI group compounds, III-V group compounds, II-V group compounds, III-VI compounds, IV-VI group compounds, I-III-VI group compounds, II-IV-VI group compounds, and group IV elemental substances. <The

[0014] In one embodiment, in the quantum dot light-emitting layer, the quantum dots include at least one of doped inorganic perovskite semiconductors, undoped inorganic perovskite semiconductors, and organic-inorganic hybrid perovskite semiconductors.

[0015] In one embodiment, the thickness of the hole injection layer is 80 to 100 nm.

[0016] In one embodiment, the thickness of the hole transport layer is 80 to 100 nm.

[0017] In one embodiment, the thickness of the quantum dot light-emitting layer is 30 to 50 nm.

[0018] In one embodiment, the thickness of the electron transport layer is 50 to 70 nm.

[0019] In one embodiment, the thickness of the electrode layer is 80 to 100 nm.

[0020] The method for preparing the quantum dot light-emitting device includes the following steps:

[0021] Growing a hole injection layer on the ITO substrate, spin-coating a fluorine-containing polymer solution on the surface of the hole injection layer to form a fluorine-containing polymer layer, and then sequentially growing a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer on the surface of the fluorine-containing polymer layer.

[0022] In one embodiment, before growing the hole injection layer, the ITO substrate further includes: ultraviolet ozone treatment;

[0023] In one embodiment, the growth conditions of the hole injection layer specifically include: spin-coating a hole injection layer solution on one side surface of the ITO substrate, and then performing a first annealing;

[0024] In one embodiment, the spin-coating rate of the hole injection layer solution is 2900 - 3100 rpm, and the spin-coating time is 25 - 35 s.

[0025] In one embodiment, the temperature of the first annealing is 130 - 150 °C, and the time of the first annealing is 25 - 35 min.

[0026] In one embodiment, the spin-coating rate of the fluoropolymer solution is 4900 - 5100 rpm, and the spin-coating time is 25 - 35 s.

[0027] In one embodiment, the growth conditions of the hole transport layer specifically include: spin-coating a hole transport layer solution on the surface of the fluoropolymer layer, and then performing a second annealing.

[0028] In one embodiment, the spin-coating rate of the hole transport layer solution is 1900 - 2100 rpm, and the spin-coating time is 40 - 50 s.

[0029] In one embodiment, the temperature of the second annealing is 100 - 120 °C, and the time of the second annealing is 25 - 35 min.

[0030] In one embodiment, the growth conditions of the quantum dot light-emitting layer specifically include: spin-coating a quantum dot solution on the surface of the hole transport layer, and then performing a third annealing.

[0031] In one embodiment, the spin-coating rate of the quantum dot solution is 3900 - 4100 rpm, and the spin-coating time is 25 - 35 s.

[0032] In one embodiment, the temperature of the third annealing is 75 - 85 °C, and the time of the third annealing is 10 - 20 min.

[0033] In one embodiment, the growth conditions of the electron transport layer specifically include: spin-coating an electron transport layer raw material solution on the surface of the quantum dot light-emitting layer, and then performing a fourth annealing.

[0034] In one embodiment, the spin-coating rate of the electron transport layer raw material solution is 2900 - 3100 rpm, and the spin-coating time is 25 - 35 s.

[0035] In one embodiment, the temperature of the fourth annealing is 75 - 85 °C, and the time of the fourth annealing is 25 - 35 min.

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] (1) In the quantum dot light-emitting device of the present invention, a fluorine-containing polymer layer is provided between the hole injection layer and the hole transport layer; the fluorine-containing polymer is a ferroelectric polymer with a high dielectric constant. Under the action of an electric field, the fluorine-containing groups in the main chain are easily polarized, and the polarized fluorine-containing groups can attract the interfacial dipoles at the interface, increase the HOME energy level of the hole injection layer, reduce the interfacial barrier between the hole injection layer and the hole transport layer, and promote the injection of holes; increase the recombination rate of electron-hole pairs and enhance the device performance.

[0038] (2) The preparation method of the quantum dot light-emitting device of the present invention can promote the injection of holes, increase the recombination rate of electron-hole pairs, and enhance the device performance. Description of the Drawings

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0040] Figure 1 It is the film-forming diagram of the quantum dot light-emitting device in Example 1;

[0041] Figure 2 It is the film-forming diagram of the quantum dot light-emitting device in Example 2;

[0042] Figure 3 It is the film-forming diagram of the quantum dot light-emitting device in Comparative Example 1;

[0043] Figure 4 It is the film-forming diagram of the quantum dot light-emitting device in Comparative Example 2. Specific Embodiments

[0044] The following will describe the implementation schemes of the present invention in detail in combination with the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. For the reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0045] According to one aspect of the present invention, the present invention relates to a quantum dot light-emitting device, which includes an ITO substrate, a hole injection layer, a fluoropolymer layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer that are sequentially stacked.

[0046] The fluoropolymer of the present invention is a ferroelectric polymer with a high dielectric constant. The fluorine-containing groups in the main chain are easily polarized under the action of an electric field. The polarized fluorine-containing groups can induce interfacial dipoles at the interface, increase the HOME energy level of the hole injection layer, reduce the interfacial barrier between the hole injection layer (HIL) and the hole transport layer (HTL), and promote the injection of holes; increase the recombination rate of electron-hole pairs and enhance the device performance.

[0047] In one embodiment, the fluoropolymer layer includes at least one of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and perfluoroethyl propylene (FEP).

[0048] In one embodiment, the thickness of the fluoropolymer layer is 70-100 nm, such as 75 nm, 80 nm, 90 nm, 95 nm, etc.

[0049] In one embodiment, the thickness of the hole injection layer is 80-100 nm, such as 85 nm, 90 nm, 95 nm, etc. In one embodiment, the thickness of the hole transport layer is 80-100 nm, such as 85 nm, 90 nm, 95 nm, etc. In one embodiment, the thickness of the quantum dot light-emitting layer is 30-50 nm, such as 35 nm, 40 nm, 45 nm, etc. In one embodiment, the thickness of the electron transport layer is 50-70 nm, such as 55 nm, 60 nm, 65 nm, etc. In one embodiment, the thickness of the electrode layer is 80-100 nm, such as 85 nm, 90 nm, 95 nm, etc.

[0050] In one embodiment, the hole transport layer includes at least one of TFB, PVK, TCTA, TPD, Poly-TPD (polytriphenylamine), and CBP.

[0051] In one embodiment, the electron transport layer includes at least one of ZnO, TiO2, SnO2, and Alq3.

[0052] In one embodiment, the hole injection layer includes at least one of PEDOT:PSS, PTPDES, PTPDES:TPBAH, PFO-co-NEPBN, PFO-co-NEPBN:F4-TCNQ, MoO2, MoO3, WO2, WO3, NiO, and CuO.

[0053] In one embodiment, in the quantum dot light-emitting layer, the quantum dots include at least one of II-VI group compounds, III-V group compounds, II-V group compounds, III-VI compounds, IV-VI group compounds, I-III-VI group compounds, II-IV-VI group compounds, and group IV elemental substances. In one embodiment, the materials of the quantum dot light-emitting layer include, but are not limited to, one or more of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, and other binary, ternary, and quaternary II-VI compounds. In one embodiment, the materials of the quantum dot light-emitting layer may include, but are not limited to, one or more of GaP, GaAs, InP, InAs, and other binary, ternary, and quaternary III-V compounds.

[0054] In one embodiment, in the quantum dot light-emitting layer, the quantum dots include at least one of doped inorganic perovskite semiconductors, undoped inorganic perovskite semiconductors, and organic-inorganic hybrid perovskite semiconductors.

[0055] In one embodiment, the general structural formula of the inorganic perovskite semiconductor is AMX3, where A is a Cs+ ion; M is a divalent metal cation, including but not limited to Pb 2+ , Sn 2+ , Cu 2+ , Ni 2+ , Cd 2+ , Cr 2+ , Mn 2+ , Co 2+ , Fe 2+ , Ge 2 + , Yb 2+ or Eu 2+ ; X is a halogen anion, including but not limited to Cl - , Br - or I - . In one embodiment, the general structural formula of the organic-inorganic hybrid perovskite semiconductor is BMX3, where B is an organic amine cation, which can be selected from, but not limited to, CH3(CH2)n-2NH3 + (n≥2) or NH3(CH2)nNH3 2+(n ≥ 2); when n = 2, the inorganic metal halide octahedra MX64- are connected by sharing vertices, with the metal cation M located at the center of the halogen octahedron, and the organic amine cation B filling the voids between the octahedra to form an infinitely extended three-dimensional structure; when n > 2, the inorganic metal halide octahedra MX64- connected by sharing vertices extend in two-dimensional directions to form a layered structure, and a bilayer of organic amine cations (protonated monoamine) or a monolayer of organic amine cations (protonated diamine) are inserted between the layers, and the organic layer and the inorganic layer overlap with each other to form a stable two-dimensional layered structure; M is a divalent metal cation and can be selected from but not limited to Pb 2+ 、Sn 2+ 、Cu 2+ 、Ni 2+ 、Cd 2+ 、Cr 2+ 、Mn 2+ 、Co 2+ 、Fe 2 + 、Ge 2+ 、Yb 2+ 、Eu 2+ ; X is a halogen anion and can be selected from but not limited to Cl - 、Br - or I - 。

[0056] According to another aspect of the present invention, the present invention also relates to a method for preparing the quantum dot light-emitting device, comprising the following steps:

[0057] A hole injection layer is grown on the ITO substrate, a fluorine-containing polymer solution is spin-coated on the surface of the hole injection layer to form a fluorine-containing polymer layer, and then a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer are sequentially grown on the surface of the fluorine-containing polymer layer.

[0058] The method of the present invention is simple and easy to implement; this method can promote the injection of holes, improve the recombination rate of electron-hole pairs, and enhance the device performance.

[0059] In one embodiment, before growing the hole injection layer, the ITO substrate is cleaned and treated with ultraviolet ozone. In one embodiment, the ITO substrate is ultrasonically cleaned in a cleaning agent, deionized water, acetone, and isopropyl alcohol in sequence for 12 - 16 min; then the surface is dried with a nitrogen gun, and then treated with ultraviolet ozone for 4 - 6 min.

[0060] In one embodiment, the growth conditions of the hole injection layer specifically include: spin-coating the hole injection layer solution on one surface of the ITO substrate and then performing a first annealing. In one embodiment, the spin-coating rate of the hole injection layer solution is 2900 - 3100 rpm, such as 2920 rpm, 2950 rpm, 2970 rpm, 3000 rpm, 3020 rpm, 3050 rpm, 3070 rpm or 3090 rpm. In one embodiment, the spin-coating time of the hole injection layer solution is 25 - 35 s, such as 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 33 s, etc. In one embodiment, the temperature of the first annealing is 130 - 150 °C, such as 135 °C, 137 °C, 140 °C, 142 °C, 145 °C, 147 °C, etc.; the time of the first annealing is 25 - 35 min, such as 26 min, 27 min, 28 min, 30 min, 32 min, 33 min, etc.

[0061] In one embodiment, the spin-coating rate of the fluoropolymer solution is 4900 - 5100 rpm, such as 4900 rpm, 4950 rpm, 5000 rpm, 5050 rpm or 5010 rpm, etc. In one embodiment, the spin-coating time of the fluoropolymer solution is 25 - 35 s, such as 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 33 s, etc.

[0062] In one embodiment, the growth conditions of the hole transport layer specifically include: spin-coating the hole transport layer solution on the surface of the fluoropolymer layer and then performing a second annealing. In one embodiment, the spin-coating rate of the hole transport layer solution is 1900 - 2100 rpm, such as 1900 rpm, 1950 rpm, 2000 rpm, 2050 rpm, 2100 rpm, etc. In one embodiment, the spin-coating time of the hole transport layer solution is 40 - 50 s, such as 41 s, 42 s, 45 s, 46 s or 47 s, etc. In one embodiment, the temperature of the second annealing is 100 - 120 °C, such as 102 °C, 105 °C, 107 °C, 108 °C, 110 °C, 112 °C, 115 °C, 117 °C, etc.; the time of the second annealing is 25 - 35 min, such as 26 min, 28 min, 30 min, 32 min, 34 min, etc.

[0063] In one embodiment, the growth conditions of the quantum dot light-emitting layer specifically include: spin-coating a quantum dot solution on the surface of the hole transport layer, and then performing a third annealing. In one embodiment, the spin-coating rate of the quantum dot solution is 3900-4100 rpm, such as 3920 rpm, 3950 rpm, 3990 rpm, 4000 rpm, 4050 rpm, 4100 rpm, etc.; the spin-coating time of the quantum dot solution is 25-35 s. In one embodiment, the temperature of the third annealing is 75-85 °C, such as 76 °C, 78 °C, 80 °C, 82 °C, 84 °C, etc.; the time of the third annealing is 10-20 min, such as 12 min, 15 min, 16 min, 18 min, etc. In one embodiment, the concentration of the quantum dot solution is 18-22 mg / mL.

[0064] In one embodiment, the growth conditions of the electron transport layer specifically include: spin-coating a raw material solution of the electron transport layer, such as ZnO solution, TiO2 solution, SnO2 solution or Alq3 solution, on the surface of the quantum dot light-emitting layer, and then performing a fourth annealing. In one embodiment, the spin-coating rate of the raw material solution of the electron transport layer is 2900-3100 rpm, such as 2920 rpm, 2950 rpm, 2970 rpm, 2990 rpm, 3000 rpm, 3050 rpm, 3100 rpm, etc.; the spin-coating time of the quantum dot solution is 25-35 s, such as 26 s, 27 s, 28 s, 29 s, 30 s, 31 s, 33 s, etc.; in one embodiment, the temperature of the fourth annealing is 75-85 °C, such as 76 °C, 78 °C, 80 °C, 82 °C, 85 °C, etc.; the time of the fourth annealing is 25-35 min, such as 26 min, 28 min, 30 min, 32 min, 34 min, etc.

[0065] The following is further explained with specific examples and comparative examples.

[0066] Example 1

[0067] A method for preparing a quantum dot light-emitting device includes the following steps:

[0068] The ITO-coated glass substrate was successively cleaned with glass cleaner, deionized water, ethanol, acetone, and isopropyl alcohol; then, it was subjected to ultraviolet ozone treatment for 5 min in an atmospheric environment; a PEDOT:PSS(4083) aqueous solution was spin-coated with a spin-coated thickness of 90 nm, and then annealed at 140 °C for 30 min. After that, a layer of polymer PVDF was dropped, with a spin-coating rate of 5000 rpm and a time of 30 s, and the spin-coated thickness was 70 nm; the hole transport layer TFB was spin-coated on the PEDOT:PSS film at a rotational speed of 2000 r / min with a spin-coated thickness of 90 nm and annealed at 120 °C for 20 min; then, the light-emitting layer InP / ZnSe / ZnSeS quantum dots were spin-coated at a speed of 4000 r / min with the spin-coated thickness controlled at 40 nm and annealed at 80 °C for 15 min; the electron transport layer ZnO was spin-coated at a speed of 4000 r / min with the spin-coated thickness controlled at 60 nm and annealed; finally, the Ag electrode was vacuum deposited under a high vacuum condition with a pressure lower than 5×10 -5 Pa to form the cathode electrode, thereby preparing the target device with the structure of ITO / PEDOT:PSS / PVDF / TFB / InP / ZnSe / ZnSeS QDs / ZnO / Ag;

[0069] Among them, the preparation method of the light-emitting layer InP / ZnSe / ZnSeS quantum dots includes: adding 1.2 mmol of indium acetate (In(Ac)3), 0.6 mmol of zinc acetate (Zn(Ac)2), and 3.6 mmol of palmitic acid (PA) into a three-necked flask, heating to 150 °C, dissolving 0.8 mmol of tris(trimethylsilyl)phosphine ((TMS)3P) in 1 mL of trioctylphosphine (TOP) and injecting it into the above solution, and quickly heating to 290 °C to react for 5 min to obtain the InP core; injecting the cleaned InP into a 10M Zn(OA)2 solution, adding a 0.2M Se-TOP solution at 170 °C, quickly heating to 320 °C, dropping in 1M S-TOP and 4M Se+TOP, reacting for 30 min, cleaning and drying, and preparing a solution with OCT.

[0070] Example 2

[0071] The preparation method of the quantum dot light-emitting device includes the following steps:

[0072] The ITO-coated glass substrate was successively cleaned with glass cleaner, deionized water, ethanol, acetone, and isopropyl alcohol; then, it was subjected to ultraviolet ozone treatment for 5 min in an atmospheric environment; a PEDOT:PSS(4083) aqueous solution was spin-coated with a spin-coated thickness of 90 nm, and then annealed at 140 °C for 30 min. After that, a layer of polymer PVDF (polyvinylidene fluoride) was dropped, with a spin-coating rate of 5000 rpm for 30 s and a spin-coated thickness of 70 nm; the hole transport layer TFB was spin-coated on the PEDOT:PSS film at a rotation speed of 2000 r / min with a spin-coated thickness of 90 nm and annealed at 120 °C for 20 min; then, the light-emitting layer CdSe / CdZnSe quantum dots were spin-coated at a speed of 4000 r / min with a spin-coated thickness controlled at 40 nm and annealed at 80 °C for 15 min; the electron transport layer ZnO was spin-coated at a speed of 4000 r / min with a spin-coated thickness controlled at 60 nm and annealed; finally, the Ag electrode was vacuum deposited under a high vacuum condition with a pressure lower than 5×10 -5 Pa to form a cathode electrode, thereby fabricating a target device with the structure of ITO / PEDOT:PSS / PVDF / TFB / CdSe / CdZnSe QDs / ZnO / Ag;

[0073] Among them, the preparation method of CdSe / CdZnSe quantum dots includes: weighing 8 mmol of cadmium oxide, 8 mL of OA, and 72 mL of ODE in a three-necked flask, evacuating it with a vacuum pump and then filling it with argon, repeating this process several times to fill the three-necked flask with argon, and slowly heating it to 240 °C to completely convert it into cadmium oleate; continuing to heat the cadmium oleate solution to 320 °C, and then quickly injecting the TOP-Se precursor into the reaction kettle at 280 °C, reacting for about 5 min to prepare the CdSe core; injecting the cleaned CdSe core into a 5M Zn(OA)2 solution, heating it to 315 °C, and simultaneously dropping 0.5M Se-TOP and 0.02M Cd-TOP solutions, reacting for 30 min, cleaning and drying it, and preparing a solution with OCT.

[0074] Example 3

[0075] The preparation method of a quantum dot light-emitting device includes the following steps:

[0076] The ITO-coated glass substrate was successively cleaned with glass cleaner, deionized water, ethanol, acetone, and isopropyl alcohol; then, it was subjected to ultraviolet ozone treatment for 5 min in an atmospheric environment; an aqueous solution of PTPDES was spin-coated, and after annealing at 145 °C for 25 min, a layer of the polymer polyvinylidene fluoride-hexafluoropropylene was dropped, with a spin-coating rate of 4900 rpm and a time of 35 s; then, the hole transport layer TPD was spin-coated on the above polymer film at a rotation speed of 1900 r / min and annealed at 110 °C for 25 min; then, the light-emitting layer InP / ZnSe / ZnSeS quantum dots were spin-coated at a speed of 4100 r / min and annealed at 75 °C for 20 min; the electron transport layer SnO2 was spin-coated at a speed of 4100 r / min and annealed; finally, the Ag electrode was vacuum-deposited under a high vacuum condition with a pressure lower than 5×10 -5 Pa to form a cathode electrode, thereby fabricating a target device with the structure of ITO / PTPDES / PVDF-HFP / TPD / InP / ZnSe / ZnSeS QDs / SnO2 / Ag;

[0077] The preparation method of CdSe / CdZnSe quantum dots was the same as that in Example 1.

[0078] Example 4

[0079] A preparation method of a quantum dot light-emitting device, comprising the following steps:

[0080] The ITO-coated glass substrate was successively cleaned with glass cleaner, deionized water, ethanol, acetone, and isopropyl alcohol; then, it was subjected to ultraviolet ozone treatment for 5 min in an atmospheric environment; an aqueous solution of PFO-co-NEPBN was spin-coated, and after annealing at 135 °C for 35 min, a layer of the polymer perfluoroethylenepropylene was dropped, with a spin-coating rate of 5100 rpm and a time of 25 s; the hole transport layer TCTA was spin-coated on the PEDOT:PSS film at a rotation speed of 2100 r / min and annealed at 125 °C for 15 min; then, the light-emitting layer CdSe / CdZnSe quantum dots were spin-coated at a speed of 3900 r / min and annealed at 85 °C for 10 min; the electron transport layer TiO2 was spin-coated at a speed of 3900 r / min and annealed; finally, the Ag electrode was vacuum-deposited under a high vacuum condition with a pressure lower than 5×10 -5 Pa to form a cathode electrode, thereby fabricating a target device with the structure of ITO / PFO-co-NEPBN / FEP / TCTA / CdSe / CdZnSe QDs / TiO2 / Ag; The preparation method of CdSe / CdZnSe quantum dots was the same as that in Example 2.

[0081] Comparative Example 1

[0082] The structure of the quantum dot light-emitting device is ITO / PEDOT:PSS / TFB / InP / ZnSe / ZnSe SQDs / ZnO / Ag; the difference from Example 1 is that it does not contain PVDF.

[0083] Comparative Example 2

[0084] The structure of the quantum dot light-emitting device is ITO / PEDOT:PSS / TFB / CdSe / CdZnSe QDs / ZnO / Ag; the difference from Example 2 is that it does not contain PVDF.

[0085] Experimental Example

[0086] Under the same conditions, the quantum dot light-emitting devices of Examples 1-2 and Comparative Examples 1-2 were heat-treated in an oven at 100 °C for 10 h, and then the film-forming quality, lifespan, and efficiency of the devices were tested using the same testing method. The lifespan and efficiency of the devices were tested using an Ocean Optics EQE testing system. EQE represents the ratio of photons obtained through internal electron-hole recombination to all incident photons, and T95 represents the time required for the device brightness to decay from the highest point to 95% of it. Among them, for the film-forming quality of Example 1, see Figure 1 ; for the film-forming quality of Example 2, see Figure 2 ; for the film-forming quality of Comparative Example 1, see Figure 3 ; for the film-forming quality of Comparative Example 2, see Figure 4 ; it can be seen that the film-forming quality of the quantum dot light-emitting devices in the examples of the present invention is better than that of the comparative examples. The lifespan and efficiency of the devices are shown in Table 1.

[0087] Table 1 Test results of the efficiency and lifespan of the devices

[0088]

[0089]

[0090] As can be seen from Table 1, by inserting a fluoropolymer layer between the hole injection layer and the hole transport layer in the present invention, the injection of holes can be promoted, the recombination rate of electron-hole pairs can be increased, and the device performance can be enhanced; the efficiency and lifespan of the devices in the examples of the present invention are much higher than those of the corresponding devices in the comparative examples.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A quantum dot light-emitting device, characterized in that, It includes an ITO substrate, a hole injection layer, a fluoropolymer layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer that are sequentially stacked; The fluoropolymer layer is selected from at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, and perfluoroethylenepropylene; The thickness of the fluoropolymer layer is 70-100 nm; The preparation method of the quantum dot light-emitting device includes the following steps: Growing a hole injection layer on the ITO substrate, spin-coating a fluoropolymer solution on the surface of the hole injection layer to form a fluoropolymer layer, and then sequentially growing a hole transport layer, a quantum dot light-emitting layer, an electron transport layer, and an electrode layer on the surface of the fluoropolymer layer; The spin-coating rate of the fluoropolymer solution is 4900-5100 rpm, and the spin-coating time is 25-35 s.

2. The quantum dot light-emitting device according to claim 1, wherein, It includes at least one of the following features (1) to (3): (1) The hole transport layer includes at least one of TFB, PVK, TCTA, TPD, Poly:TPD, and CBP; (2) The electron transport layer includes at least one of ZnO, TiO2, SnO2, and Alq3; (3) The hole injection layer includes at least one of PEDOT:PSS, PTPDES, PTPDES:TPBAH, PFO-co-NEPBN, PFO-co-NEPBN:F4-TCNQ, MoO2, MoO3, WO2, WO3, NiO, and CuO.

3. The quantum dot light-emitting device according to claim 1, wherein It includes one of the following features (1) or (2): (1) In the quantum dot light-emitting layer, the quantum dots include at least one of II-VI group compounds, III-V group compounds, II-V group compounds, III-VI compounds, IV-VI group compounds, I-III-VI group compounds, II-IV-VI group compounds, and group IV elemental substances; (2) In the quantum dot light-emitting layer, the quantum dots include at least one of doped inorganic perovskite semiconductors, undoped inorganic perovskite semiconductors, and organic-inorganic hybrid perovskite semiconductors.

4. The quantum dot light-emitting device according to claim 1, wherein, It includes one of the following features (1) or (5): (1) The thickness of the hole injection layer is 80-100 nm; (2) The thickness of the hole transport layer is 80-100 nm; (3) The thickness of the quantum dot light-emitting layer is 30-50 nm; (4) The thickness of the electron transport layer is 50-70 nm; (5) The thickness of the electrode layer is 80-100 nm.

5. The quantum dot light-emitting device according to claim 1, wherein It includes at least one of the following features (1) to (4): (1) Before growing the hole injection layer on the ITO substrate, it further includes: ultraviolet ozone treatment; (2) The growth conditions of the hole injection layer specifically include: spin-coating the hole injection layer solution on one side surface of the ITO substrate, and then performing the first annealing; (3) The spin-coating rate of the hole injection layer solution is 2900-3100 rpm, and the spin-coating time is 25-35 s; (4) The temperature of the first annealing is 130-150 °C, and the time of the first annealing is 25-35 min.

6. The quantum dot light-emitting device according to claim 1, characterized in that, Comprising at least one of the following features (1) to (3): (1) The growth conditions of the hole transport layer, specifically including: spin-coating a hole transport layer solution on the surface of the fluoropolymer layer, and then performing a second annealing; (2) The spin-coating rate of the hole transport layer solution is 1900 - 2100 rpm, and the spin-coating time is 40 - 50 s; (3) The temperature of the second annealing is 100 - 120 °C, and the time of the second annealing is 25 - 35 min.

7. The quantum dot light emitting device according to claim 1, wherein, Comprising at least one of the following features (1) to (6): (1) The growth conditions of the quantum dot light-emitting layer, specifically including: spin-coating a quantum dot solution on the surface of the hole transport layer, and then performing a third annealing; (2) The spin-coating rate of the quantum dot solution is 3900 - 4100 rpm, and the spin-coating time is 25 - 35 s; (3) The temperature of the third annealing is 75 - 85 °C, and the time of the third annealing is 10 - 20 min; (4) The growth conditions of the electron transport layer, specifically including: spin-coating an electron transport layer raw material solution on the surface of the quantum dot light-emitting layer, and then performing a fourth annealing; (5) The spin-coating rate of the electron transport layer raw material solution is 2900 - 3100 rpm, and the spin-coating time is 25 - 35 s; (6) The temperature of the fourth annealing is 75 - 85 °C, and the time of the fourth annealing is 25 - 35 min.

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