QLED device based on cubic core-shell multi-well quantum well light-emitting layer and preparation method thereof

Abstract

The application discloses a kind of QLED devices based on cubic core-shell multi-well quantum well light-emitting layer and preparation method thereof, by with P-type material tin selenide as core, with N-type material zinc selenide as shell, with P-type material tin selenide as second well layer, again with N-type material zinc selenide as shell cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well as light-emitting layer, preparation includes organic hole transport layer, inorganic electron transport layer, light-emitting layer LED device.The application uses hot injection method to prepare cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well material, its structure is novel, light-emitting layer morphology is excellent regular, device structure is stable and efficient, the quantum well material prepared has continuous PN heterostructure, cubic morphology, good structural stability, the quantum well LED device prepared has excellent electroluminescent efficiency and external quantum efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of material science, and particularly relates to a QLED device based on a cubic core-shell multi-well quantum well light-emitting layer and a preparation method thereof. BACKGROUND

[0002] With the rapid development of display technology, the performance requirements of display products are increasing. Compared with traditional organic light-emitting diodes, quantum dot light-emitting diodes have attracted widespread attention from researchers due to their high color purity, adjustable color, long service life of inorganic materials and other advantages. Tin selenide quantum dots are considered to be a very promising light-emitting material due to their narrow band gap and excellent morphology adjustment capability. However, there are few studies on tin selenide quantum dot LEDs at present, mainly because the excitation wavelength is concentrated in near-infrared light emission and the PLQY is low, making it difficult to prepare stable and efficient quantum dot LED devices.

[0003] Studies have shown that strictly controlling the temperature and precursor ratio during the synthesis of tin selenide nanocrystals can easily control the morphology of the quantum dots. Some studies have also coated other band-matched material shells on tin selenide quantum dots to form a single-well core-shell structure, which can significantly excite the wavelength and passivate surface defects, thereby improving the optical performance. (CN107697892A) provides a preparation method of urchin-like tin selenide: adding oleic acid and oleylamine as surfactants in an alcohol solution of selenium dioxide and tin source to improve the surface structure of tin selenide. Literature J. Phys. Chem. Lett. 2021, 12, 10958−10968 proposes a preparation method of SnSe / CdSe core-shell structure quantum dots, and the presence of the cadmium selenide shell significantly improves the luminescent performance of SnSe material. Literature CrystEngComm, 2011, 13, 4161–4166 proposes that the morphology of SnSe material can be effectively adjusted according to the ratio of precursors, effectively expanding the application field of SnSe material. Although their methods improve the performance of tin selenide nanocrystals to some extent, they have little improvement in the morphology and core-shell structure of quantum dots. Therefore, it is necessary to further study the application of tin selenide quantum well in LED devices by artificially designing the morphology of the material and the energy level matching of the material to effectively promote the coordination of the luminescence of tin selenide quantum well material.

[0004] In summary, the morphology quality and emission performance of the tin selenide material mentioned in most of the literature or patents cannot be well controlled in theory, thereby affecting the application of tin selenide material in LED light-emitting devices. At the same time, the application of tin selenide material in the current patents is limited to the formation of PN structure photodetectors by magnetron sputtering thin film or nanosheet-shaped electrode materials, and the optimization effect in the electroluminescence field is limited. SUMMARY

[0005] The application aims to provide a QLED device based on a cubic core-shell multi-well quantum well light-emitting layer and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the application adopts the following technical scheme:

[0007] A QLED device based on a cubic core-shell multi-well quantum well light-emitting layer, which comprises a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well with a P-type material tin selenide as a core, an N-type material zinc selenide as a shell, a P-type material tin selenide as a second well layer, and an N-type material zinc selenide as a shell.

[0008] The preparation method of the QLED device based on the cubic core-shell multi-well quantum well light-emitting layer comprises the following steps:

[0009] (1) The ITO conductive glass is cleaned with deionized water, acetone and isopropanol for 15-25 min, and dried with nitrogen at a certain temperature;

[0010] (2) The PEDOT:PSS solution is spin-coated on the ITO conductive glass of step (4) in the glove box, and then the conductive glass sheet is placed on the heating table for annealing;

[0011] (3) The TFB is dissolved in toluene solution, and then the solution is spin-coated on the conductive glass sheet of step (5) in the glove box, and then the conductive glass sheet is placed on the heating table for annealing;

[0012] (4) The cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well solution is spin-coated on the conductive glass sheet of step (6) in the glove box, and then the conductive glass sheet is placed on the heating table for annealing;

[0013] (5) The Zn0.85Mg0.15O solution is spin-coated on the conductive glass sheet of step (7) in the glove box, and then the conductive glass sheet is placed on the heating table for annealing;

[0014] (6) the conductive glass sheet obtained in step (8) is evaporated with an electrode using a thermal evaporation machine, thereby obtaining the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well material LED preparation method.

[0015] Further, the PEDOT:PSS solution in step (2) is filtered through a 0.45 μm filter head, the annealing temperature is 100-120 °C, the environmental condition is in a glove box with less than 1 ppm of oxygen and water in a nitrogen atmosphere, and the annealing time is 20-30 min.

[0016] Further, the TFB solution in step (3) has a concentration of 8-10 mg / ml, the annealing temperature is 160-200 °C, the environmental condition is in a glove box with less than 1 ppm of oxygen and water in a nitrogen atmosphere, and the annealing time is 15-30 min.

[0017] Further, the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well solution in step (4) has a concentration of 20-40 mg / ml, the annealing temperature is 60-80 °C, the environmental condition is in a glove box with less than 1 ppm of oxygen and water in a nitrogen atmosphere, and the annealing time is 10-20 min.

[0018] Further, the Zn0.85Mg0.15O solution in step (5) has a concentration of 15-25 mg / ml, the annealing temperature is 100-120 °C, the environmental condition is in a glove box with less than 1 ppm of oxygen and water in a nitrogen atmosphere, and the annealing time is 10-20 min.

[0019] Further, the electrode in step (6) is a silver electrode with a thickness of 100 nm.

[0020] The beneficial effects of the present application are that: the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well is used as the light-emitting layer, the LED device comprising an organic hole transport layer, an inorganic electron transport layer and the light-emitting layer is prepared, compared with the prior art, the present application can facilitate the control of the core-shell structure, has the characteristics of stable device structure and rapid process, and can effectively reduce the performance loss of the quantum well caused by the device preparation process. At the same time, the zinc selenide and tin selenide are alternately coated, the multi-layer PN heterostructure is effectively formed, the interface contact of the heterojunction causes the bending of the energy band, the existence of the depletion region promotes the recombination of the electrons and holes, and the material properties bring higher electron and hole wave function overlap. By controlling the ratio of tin source and selenium source to be 2:1 or 1:2, the increase of the total chemical potential of the reaction solution will produce nanocrystals with higher chemical potential, improve the structural stability, quantum efficiency and photoluminescence intensity of the quantum well material. In addition, the device process of the present application is coherent and simple, the thickness of each layer component is easy to adjust, and the light-emitting layer is the recombination center of the electron and hole current, which is an effective method for preparing high-performance light-emitting quantum well materials and devices.

[0021] The present application can fully utilize the excellent energy band regulation capability of the PN heterojunction material in the quantum well light-emitting aspect, prepare a PN junction type quantum well material with tin selenide as the well region, and further design the device structure to optimize the electroluminescent performance of the device; obtain a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well material LED with high external quantum efficiency and high light-emitting intensity. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well structure diagram;

[0023] Figure 2 is an LED structure diagram prepared by using the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well as the light-emitting layer;

[0024] Note: 1 is a P-type material SnSe core, 2 is an N-type material ZnSe, 3 is a P-type material SnSe, 4 is an N-type material ZnSe, 5 is a silver electrode, 6 is Zn 0.85 Mg 0.15 O electron transport layer, 7 is a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well material light-emitting layer, 8 is a TFB hole transport layer, 9 is a PEDOT:PSS hole transport layer, and 10 is an ITO glass substrate. DETAILED DESCRIPTION

[0025] The application aims to provide a preparation method of an LED device with a cubic multi-well core-shell quantum well as a light-emitting layer

[0026] Example 1

[0027] 1) Put the ITO glass into a beaker, and sequentially pour acetone solution, isopropyl alcohol solution and deionized water solution into the beaker, and ultrasonically clean each for 25 min. Take out, dry under nitrogen at 60°C, and place in a clean and dry culture dish.

[0028] 2) After filtering the PEDOT:PSS solution with a 0.45 μm filter head, spin-coat the solution on the ITO glass by using a spin coater at a low speed of 500 rpm / s for 5 s and a high speed of 3000 rpm / s for 40 s, and then place the glass sheet on a heating table to anneal at 120°C for 30 min.

[0029] 3) Take 8 mg of TFB and 1 ml of toluene, dissolve the TFB in toluene to prepare a solution with a concentration of 8 mg / mL, and then spin-coat the solution on the glass sheet by using a spin coater at a low speed of 500 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s, and then place the glass sheet on a heating table to anneal at 200°C for 20 min.

[0030] 4) Preparation of the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well: mix 0.25 mmol of tin acetate, 4 ml of oleylamine, 1 ml of oleic acid and 10 ml of octadecene in a three-necked flask, first vacuumize at room temperature for 2 min, maintain under nitrogen atmosphere for 10 min, and then repeat the vacuumizing and charging for 2 times, then increase the temperature to 160°C, inject 0.5 mmol of selenium powder dissolved in 5 ml of oleic acid, react for 5 min, then increase the temperature to 240°C, inject 0.2 mmol of zinc acetate dissolved in 1 ml of a mixed solution of oleic acid and 2 ml of octadecene, react for 8 min, then clean with ethanol and n-hexane, and then redissolve with octadecene, and repeat the above steps to obtain the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well. Dilute the quantum well solution to a concentration of 25 mg / ml, spin-coat the solution on the glass sheet by using a spin coater at a low speed of 500 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s, and then place the glass sheet on a heating table to anneal at 80°C for 10 min. Figure 1 is a structure diagram of the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well, wherein 1 is a P-type material SnSe core, 2 is an N-type material ZnSe, 3 is a P-type material SnSe, and 4 is an N-type material ZnSe.

[0031] 5) Zn0.85Mg0.15O solution with a concentration of 20 mg / ml was spin-coated at a low speed of 500 rpm / s for 5 s and a high speed of 1000 rpm / s for 40 s, and then the glass sheet was placed on a heating stage to be annealed at 80°C for 10 min.

[0032] 6) 100 nm silver electrode was thermally evaporated to obtain an LED prepared with cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well as the light-emitting layer. Figure 2 is a structure diagram of an LED prepared with cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well as the light-emitting layer, wherein 5 is a silver electrode, 6 is Zn 0.85 Mg 0.15 O electron transport layer, 7 is a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well material light-emitting layer, 8 is a TFB hole transport layer, 9 is a PEDOT:PSS hole transport layer, and 10 is an ITO glass substrate.

[0033] Example 2

[0034] 1) The ITO glass was placed in a beaker and then acetone solution, isopropanol solution and deionized water solution were poured in turn and each was ultrasonically cleaned for 25 min. After being taken out, it was dried by blowing nitrogen at 60°C and then placed in a clean and dry culture dish.

[0035] 2) After the PEDOT:PSS solution was filtered with a 0.45 μm filter head, it was spin-coated on the ITO glass using a spin coater at a low speed of 500 rpm / s for 5 s and a high speed of 3500 rpm / s for 40 s, and then the glass sheet was placed on a heating stage to be annealed at 150°C for 25 min.

[0036] 3) After TFB 8 mg and toluene solution 1 ml were dissolved in toluene to prepare a solution with a concentration of 8 mg / mL, the solution was spin-coated using a spin coater at a low speed of 500 rpm / s for 5 s and a high speed of 3000 rpm / s for 40 s, and then the glass sheet was placed on a heating stage to be annealed at 150°C for 15 min.

[0037] 4) Preparation of cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well: 0.2 mmol tin acetate, 4 ml oleylamine, 1 ml oleic acid, 10 ml octadecene were mixed in a three-necked flask, vacuumed at room temperature for 2 min, maintained for 10 min under nitrogen atmosphere, and then vacuumed and filled for 2 times repeatedly, then the temperature was increased to 180°C, 0.5 mmol selenium powder was dissolved in 4 ml oleic acid and injected, the temperature was increased to 220°C after 5 min, 0.2 mmol zinc acetate was dissolved in 1 ml oleic acid and 2 ml octadecene mixed solution and then injected, the reaction was carried out for 10 min, then the quantum well solution was washed with ethanol and n-hexane, and then redissolved with octadecene, and the above steps were repeated to obtain cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well. The quantum well solution was diluted to 25 mg / ml, and then spin-coated at a low speed of 500 rpm / s for 5 s and a high speed of 2000 rpm / s for 40 s, and then the glass sheet was placed on a heating stage and annealed at 60°C for 10 min. Figure 1 is a structure diagram of cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well, wherein 1 is a P-type SnSe core, 2 is an N-type ZnSe, 3 is a P-type SnSe, and 4 is an N-type ZnSe.

[0038] 5) 20 mg / ml concentration of Zn0.85Mg0.15O solution was prepared, and then spin-coated at a low speed of 500 rpm / s for 5 s and a high speed of 1000 rpm / s for 40 s, and then the glass sheet was placed on a heating stage and annealed at 60°C for 20 min.

[0039] 6) 100 nm silver electrode was prepared by thermal evaporation, and then the LED prepared by using cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well as a light-emitting layer was obtained. Figure 2 is a structure diagram of LED prepared by using cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well as a light-emitting layer, wherein 5 is a silver electrode, 6 is a Zn 0.85 Mg 0.15 O electron transport layer, 7 is a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well material light-emitting layer, 8 is a TFB hole transport layer, 9 is a PEDOT:PSS hole transport layer, and 10 is an ITO glass substrate.

[0040] The above only describes the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.

Claims

1. A QLED device based on cubic core-shell multi-well quantum well light emitting layer, characterized by: The QLED device based on the cubic core-shell multi-well quantum well light-emitting layer comprises, from bottom to top, an electrode, an inorganic electron transport layer, a light-emitting layer, an organic hole transport layer and an ITO glass substrate, wherein the light-emitting layer is a cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well with a P-type material tin selenide as a core, an N-type material zinc selenide as a shell, a P-type material tin selenide as a second well layer, and an N-type material zinc selenide as a shell again. The preparation method of the QLED device based on the cubic core-shell multi-well quantum well light-emitting layer comprises the following steps: (1) The ITO conductive glass is cleaned with deionized water, acetone and isopropanol for 15-25 minutes respectively, and dried with nitrogen at a certain temperature; (2) In the glove box, the PEDOT:PSS solution is spin-coated on the ITO conductive glass of step (1) using a spin coater, and then the conductive glass sheet is placed on a heating table for annealing; (3) TFB is dissolved in toluene solution, and then the solution is spin-coated on the conductive glass sheet of step (2) using a spin coater in the glove box, and then the conductive glass sheet is placed on a heating table for annealing; (4) In the glove box, the cubic SnSe / ZnSe / SnSe / ZnSe multi-well core-shell quantum well solution is spin-coated on the conductive glass sheet of step (3) using a spin coater, and then the conductive glass sheet is placed on a heating table for annealing; (5) In a glove box, Zn 0.85 Mg 0.15 The solution of O was spin-coated on the conductive glass sheet of step (4) using a spin coater, and then the conductive glass sheet was placed on a heating stage for annealing; (6) The conductive glass sheet obtained in step (5) is evaporated with an electrode using a thermal evaporation machine, thereby obtaining a QLED device based on a cubic core-shell multi-well quantum well light-emitting layer; In step (2), the PEDOT:PSS solution is first filtered through a 0.45 μm filter head, the annealing temperature is 100-120°C, the environmental condition is in a glove box with nitrogen atmosphere with oxygen and water less than 1 ppm, and the annealing time is 20-30 minutes; In step (3), the TFB solution has a concentration of 8-10 mg / ml, the annealing temperature is 160-200°C, the environmental condition is in a glove box with nitrogen atmosphere with oxygen and water less than 1 ppm, and the annealing time is 15-30 minutes.

2. The QLED device based on cubic core-shell multi-well quantum well light- emitting layer according to claim 1, characterized in that: The inorganic electron transport layer is a Zn0.85Mg0.15O electron transport layer.

3. The QLED device based on cubic core-shell multi-well quantum well light- emitting layer according to claim 1, characterized in that: The organic hole transport layer comprises a TFB hole transport layer and a PEDOT:PSS hole transport layer.

4. The QLED device based on cubic core-shell multi-well quantum well light- emitting layer according to claim 1, characterized in that: In step (4), the ZnSe / Cu2Se / ZnSe quantum well solution has a concentration of 20-40 mg / ml, the annealing temperature is 60-80°C, the environmental condition is in a glove box with nitrogen atmosphere with oxygen and water less than 1 ppm, and the annealing time is 10-20 minutes.

5. The QLED device based on cubic core-shell multi-well quantum well light- emitting layer according to claim 1, characterized in that: Zn 0.85 Mg 0.15 O solution concentration is 15-25 mg / ml, annealing temperature is 100-120 °C, environmental conditions are in a nitrogen glove box with less than 1 ppm of both oxygen and water, and annealing time is 10-20 min.

6. The QLED device based on cubic core-shell multi-well quantum well light- emitting layer according to claim 1, characterized in that: In step (6), the electrode is a silver electrode with a thickness of 100 nm.

Images