Aqueous-phase cdse@zns quantum dot suitable for carrier-injection-free light-emitting diode and preparation method therefor, and carrier-injection-free light-emitting diode

Abstract

Disclosed in embodiments of the present description are an aqueous phase CdSe@ZnS quantum dot suitable for a carrier-injection-free light-emitting diode and a preparation method therefor, and a carrier-injection-free light-emitting diode. In the method, a water-soluble glutathione ligand is introduced as a surface modifier, and an aqueous phase-oil phase mixed binary system is constructed on the basis of an oil-soluble CdSe@ZnS quantum dot. Because the amino and mercapto groups of the glutathione ligand have a good coordination effect, the oil-soluble CdSe@ZnS quantum dot can be converted into an aqueous-soluble quantum dot, and due to the affinity between an aqueous-phase quantum dot light-emitting layer and an insulating layer, it is expected to further improve the performance of the carrier-injection-free light-emitting diode.

Description

Aqueous CdSe@ZnS quantum dots suitable for carrier-injection-free LEDs and their preparation method, carrier-injection-free LEDs

[0001] This application claims priority to Chinese Patent Application No. 202411577005.0, filed on November 6, 2024, entitled "Aqueous CdSe@ZnS Quantum Dots Suitable for Carrier-Free Injection Light Emitting Diodes and Their Preparation Methods, and Carrier-Free Injection Light Emitting Diodes", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of novel nano-optoelectronic material preparation technology, and in particular to an aqueous CdSe@ZnS quantum dot suitable for carrier-injection-free electroluminescent devices, its preparation method, and a method for preparing a carrier-injection-free light-emitting diode. Background Technology

[0003] Carrier-injection-free light-emitting diodes (LEDs) hold promise for applications in novel micro-display technologies such as Micro-LEDs and nano-pixel light-emitting displays due to their simple device structure, demonstrating broad application prospects in the field of optoelectronic devices. This device structure eliminates the need for external carrier injection, relying instead on the periodic recombination and separation of inherent carriers within the device to achieve light output. In the structure of carrier-injection-free LEDs, the light-emitting layer is typically in contact with a polar-phase-based insulating or functional layer. Since these thin films are usually hydrophilic, a suitable light-emitting layer needs to be introduced.

[0004] Quantum dots, as a very important class of nanomaterials, possess advantages such as narrow half-maximum width at half-maximum (HWHM), tunable emission wavelength, and high color purity, and have attracted widespread attention in the field of novel displays. Traditional quantum dot synthesis methods often face various challenges such as limited wavelength tuning range, low quantum yield, and poor water solubility. In order to improve the uniform spreading of the emitting layer on the insulating layer of the device, an efficient and flexible strategy for synthesizing polar phase quantum dots is needed.

[0005] Summary of the Invention

[0006] This invention provides an aqueous CdSe@ZnS quantum dot and its synthesis method suitable for carrier-injection-free devices, addressing the unique structure of carrier-injection-free light-emitting diodes. By utilizing water-soluble short-chain amino acid ligands to modify the surface of oil-phase CdSe@ZnS, its phase state can be transferred to the aqueous phase without significantly reducing its luminescence performance. This effectively improves the uniform spreading of the luminescent layer on the insulating or functional layers of the device, enhancing the carrier-injection-free electroluminescence performance of CdSe@ZnS quantum dots.

[0007] This invention provides an aqueous CdSe@ZnS quantum dot suitable for carrier-injection-free light-emitting diodes, comprising a light-emitting core and surface ligands located on the surface of the light-emitting core; the light-emitting core comprises oil-soluble CdSe@ZnS quantum dots, and the surface ligands comprise short-chain amino acid ligands, wherein the short-chain amino acid ligands comprise any one or more combinations of glutathione, histidine, and cysteine.

[0008] This invention provides a method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-injection-free light-emitting diodes, comprising the following steps:

[0009] Step 1: Add cadmium acetate and zinc oxide to oleic acid to react, heat the reaction system to a first temperature, degas the reaction at the first temperature, then add octadecene and heat to a second temperature to obtain cadmium-zinc precursor solution;

[0010] Step 2: Add sulfur powder and selenium powder to tri-n-octylphosphine for reaction, and heat the reaction system to the third temperature to obtain selenium-sulfur precursor solution;

[0011] Step 3: Inject the reaction product obtained in Step 2 into the reaction product in Step 1, and maintain the reaction system at the second temperature for a period of time before cooling it to room temperature;

[0012] Step 4: After washing the CdSe@ZnS quantum dots obtained in Step 3 with a mixed solution of n-hexane and acetone, disperse them in the nonpolar solvent chloroform.

[0013] Step 5: Dissolve the short-chain amino acid ligand in water, and add sodium hydroxide solution, zinc chloride solution, and thiourea solution in sequence;

[0014] Step 6: Add the aqueous solution obtained in Step 5 to the nonpolar CdSe@ZnS quantum dots obtained in Step 4 and stir to obtain the crude aqueous CdSe@ZnS quantum dot product.

[0015] Step 7: Wash the crude aqueous CdSe@ZnS quantum dot product obtained in Step 6 with ethanol and redisperse it in deionized water to obtain aqueous CdSe@ZnS quantum dots suitable for carrier-free injection into light-emitting diodes.

[0016] Step 8: The carrier-free light-emitting diode includes a glass substrate and on which, in sequence, are a cathode, an insulating layer, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer; a vacuum-deposited electron transport layer, an electron injection layer, and an anode.

[0017] Furthermore, the molar ratio of cadmium acetate to oleic acid in step 1 is 0.01-0.1.

[0018] Further, the molar ratio of zinc oxide to oleic acid in step 1 is 0.1-0.2, preferably 0.15.

[0019] Furthermore, the volume of the octadecene in step 1 is 2-3.5 times that of oleic acid, preferably 2 times.

[0020] Furthermore, in step 1, the first temperature is 140-160℃, and the second temperature is 280-320℃.

[0021] Furthermore, the molar ratio of sulfur powder to tri-n-octylphosphine in step 2 is 0.4-0.5, preferably 0.45.

[0022] Furthermore, the molar ratio of selenium powder to tri-n-octylphosphine in step 2 is 0.4-0.5, preferably 0.45.

[0023] Furthermore, the third temperature mentioned in step 2 is 50-70℃.

[0024] Furthermore, the volume ratio of the selenium-sulfur precursor solution to the cadmium-zinc precursor solution in step 3 is 0.08-0.12.

[0025] Furthermore, in step 3, the second temperature is maintained for 10-25 minutes.

[0026] Furthermore, the mixing volume ratio of the hexane and acetone mixture in step 4 is 0.15-0.25, and the volume ratio of the CdSe@ZnS quantum dots obtained in step 3 to the washing mixture is 0.12-0.2.

[0027] Furthermore, the concentration of the nonpolar CdSe@ZnS quantum dots in step 4 is 4-6 mg / mL.

[0028] Furthermore, the short-chain amino acid ligands mentioned in step 5 include any one or more combinations of glutathione, histidine, and cysteine.

[0029] Further, in step 5, the concentration of the amino acid ligand solution is 0.3-1.0 mol / L; the concentration of the added NaOH solution is 0.8-1.2 mol / L (preferably 1 mol / L), and the pH of the system after adding the NaOH solution is 12.0-13.5.

[0030] Furthermore, in step 5, the concentration of the added zinc chloride aqueous solution is 0.2-0.3 mol / L (preferably 0.2 mol / L), and the volume is 0.5-0.7 times that of the amino acid ligand aqueous solution.

[0031] Furthermore, in step 5, the concentration of the added thiourea aqueous solution is 0.2-0.3 mol / L (preferably 0.2 mol / L), and the volume is 0.5-0.7 times that of the amino acid ligand aqueous solution.

[0032] Furthermore, the volume of the nonpolar system in step 6 is 0.3-0.4 times that of the polar system; the two-phase stirring time is 4-6 hours.

[0033] Furthermore, the volume of washing ethanol in step 7 is 1-1.5 times that of the crude aqueous CdSe@ZnS quantum dot product obtained in step 6.

[0034] This invention provides a carrier-injection-free light-emitting diode, comprising: an anode, an insulating layer, a quantum dot light-emitting layer, and a cathode stacked sequentially; wherein the material of the quantum dot light-emitting layer includes aqueous CdSe@ZnS quantum dots suitable for carrier-injection-free light-emitting diodes provided in this specification.

[0035] Furthermore, the carrier-free light-emitting diode further includes: a first functional layer disposed between the insulating layer and the quantum dot light-emitting layer; the first functional layer includes at least one of a hole injection layer and a hole transport layer;

[0036] And / or,

[0037] A second functional layer is disposed between the quantum dot light-emitting layer and the cathode; the second functional layer includes at least one of an electron injection layer and an electron transport layer.

[0038] Furthermore, the electron injection layer is located between the cathode and the quantum dot light-emitting layer; the electron transport layer is located between the electron injection layer and the quantum dot light-emitting layer; the hole injection layer is located between the quantum dot light-emitting layer and the insulating layer; and the hole transport layer is located between the quantum dot light-emitting layer and the hole injection layer.

[0039] Furthermore, the anode material can be ITO (indium tin oxide).

[0040] Furthermore, the material of the insulating layer can be PMMA (poly(methyl methacrylate)), and the spin coating conditions of the insulating layer can be: concentration 40-60 mg / mL, rotation speed 2000-2500 rpm / min, duration 30-45 s, annealing at 100-120℃ for 5-10 min.

[0041] Furthermore, the material of the hole injection layer can be PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)), and the spin coating conditions of the hole injection layer can be: a rotation speed of 4000-4200 rpm / min for 40-60 s, followed by annealing at 140-150℃ for 20-30 min.

[0042] Furthermore, the material of the hole transport layer can be TFB (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(sec-butylphenyl))diphenylamine)]), and the spin-coating conditions of the hole transport layer can be: concentration 3-6 mg / mL, rotation speed 2000-2500 rpm / min, duration 45-60 s, annealing at 100-120℃ for 20-30 min.

[0043] Furthermore, the material of the quantum dot luminescent layer can be the quantum dots obtained in step 7, and the spin-coating conditions of the quantum dot luminescent layer can be: concentration 4-6 mg / mL, rotation speed 1000-1500 rpm / min, duration 45-60 s, annealing at 50-60℃ for 5-10 min.

[0044] Furthermore, the material of the electron transport layer can be TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), and the thickness of the electron transport layer can be 60-70 nm.

[0045] Furthermore, the electron injection layer can be made of LiF, and its thickness can be 2-3 nm.

[0046] Furthermore, the cathode material can be an Al thin film, and the anode thickness can be 100-120 nm.

[0047] The advantage of this invention lies in the surface modification of oil-phase CdSe@ZnS quantum dots using water-soluble short-chain amino acid ligands. This allows for the transfer of their phase to the aqueous phase without significantly reducing their luminescence performance. It can effectively improve the uniform spreading of the luminescent layer on the insulating or functional layer of the device. Furthermore, it provides an aqueous CdSe@ZnS quantum dot and its synthesis method suitable for the unique structure of carrier-injection-free light-emitting diodes, enhancing the carrier-injection-free electroluminescence performance of CdSe@ZnS quantum dots. The entire preparation process is simple, easy to operate, and suitable for large-scale applications. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 shows TEM (Transmission Electron Microscope) images of oil-phase CdSe@ZnS quantum dots (left) and aqueous-phase CdSe@ZnS quantum dots (right) prepared in Example 1 of this invention, demonstrating that the phase transfer process in the embodiments of this specification causes a change in the morphology of the quantum dots.

[0050] Figure 2 shows a physical image of the aqueous CdSe@ZnS quantum dots prepared by the phase transfer method in Example 1 of this invention. The left image in Figure 2 shows the oil phase CdSe@ZnS quantum dots before phase transfer, and the middle image shows the reaction system of the oil phase CdSe@ZnS quantum dots and the mixture of short-chain amino acid ligands. The upper layer is a polar phase solution (transparent and colorless) of short-chain amino acid ligands, sodium hydroxide, zinc chloride, and thiourea, and the lower layer is a non-polar oil phase solution (red) based on the oil phase CdSe@ZnS quantum dots. The right image in Figure 2 shows the product after phase transfer. The lower layer is the non-polar oil phase (colorless and transparent) obtained by ligand exchange through the phase transfer method, and the upper layer is the aqueous CdSe@ZnS quantum dots (red).

[0051] Figure 3 shows the UV-vis (Ultraviolet-visible absorbance) spectra of aqueous CdSe@ZnS quantum dots (dashed line) and oil-phase CdSe@ZnS quantum dots (solid line) prepared in Example 1 of this invention.

[0052] Figure 4 shows the PL (Photoluminescence) spectra of aqueous CdSe@ZnS quantum dots (dashed line) and oil-phase CdSe@ZnS quantum dots (solid line) prepared in Example 1 of this invention, demonstrating the luminescent properties of the materials obtained by this invention;

[0053] Figure 5 shows the structure of the injection-free light-emitting device (left) fabricated based on aqueous CdSe@ZnS quantum dots in an example of the present invention and its brightness under AC voltage (30V, different frequencies) (right). Detailed Implementation

[0054] Many specific details are set forth in the following description to provide a full understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this application; therefore, this application is not limited to the specific embodiments disclosed below.

[0055] The present invention will be further described below with reference to specific accompanying drawings and embodiments. However, the scope of protection of the present invention is not limited to the following embodiments.

[0056] Example 1:

[0057] Step 1: Add 0.2-2 mmol cadmium acetate and 3-5 mmol zinc oxide to 20-25 mmol oleic acid and react. Heat the reaction system to 140-160℃ and degas at the first temperature. Then add 16-18 mL octadecene and heat to 290-310℃ to obtain cadmium-zinc precursor solution.

[0058] Step 2: Add 1.6-2.5 mmol of sulfur powder and 1.6-2.5 mmol of selenium powder to 4-5 mmol of tri-n-octylphosphine and react. Heat the reaction system to 50-70℃ to obtain the selenium-sulfur precursor solution.

[0059] Step 3: Inject 2-2.2 mL of the reaction product obtained in Step 2 into the reaction product in Step 1, maintain the reaction system at 290-310℃ for 10-25 minutes, and then cool it to room temperature;

[0060] Step 4: Wash the CdSe@ZnS quantum dots obtained in Step 3 with a mixture of 0.9-1.2 volumes of n-hexane and 4-4.5 volumes of acetone, remove the supernatant, and disperse them in the nonpolar solvent chloroform at a concentration of 4-6 mg / mL.

[0061] Step 5: Dissolve glutathione in water to obtain a glutathione solution with a concentration of 0.3-1 mol / L. Then, add 0.9-1.2 mol / L sodium hydroxide solution sequentially until the pH of the system is 12.0-13.5. Then, add 0.5-0.7 times the volume of the glutathione solution of 0.2 mol / L zinc chloride solution and 0.5-0.7 times the volume of the glutathione solution of 0.2 mol / L thiourea aqueous solution sequentially.

[0062] Step 6: Add the aqueous solution obtained in Step 5 to the nonpolar CdSe@ZnS quantum dots obtained in Step 4 at a volume of 3-3.5 times and stir for 4-6 hours to obtain the crude aqueous CdSe@ZnS quantum dot product.

[0063] Step 7: Wash the crude aqueous CdSe@ZnS quantum dot product obtained in Step 6 with 1.2-1.5 times the volume of ethanol to remove the supernatant, and redisperse it in deionized water to obtain aqueous CdSe@ZnS quantum dots suitable for carrier-free injection into light-emitting diodes.

[0064] In the method of Example 1, a water-soluble glutathione ligand was introduced as a surface modifier. A water-oil two-phase mixed binary system was constructed based on oil-soluble CdSe@ZnS quantum dots. Since the amino and thiol groups of the glutathione ligand have good coordination effects, the oil-soluble CdSe@ZnS quantum dots can be converted into water-soluble ones. Thanks to the affinity between the aqueous quantum dot light-emitting layer and the insulating layer, it is expected to further improve the performance of carrier-free injection type light-emitting diode devices.

[0065] Example 2: Fabrication of a carrier-free injected light-emitting diode.

[0066] The indexing method for carrier-injection-free light-emitting diodes includes: sequentially spin-coating an anode, an insulating layer, a hole injection layer, a hole transport layer, and a quantum dot light-emitting layer on a glass substrate, and then sequentially vacuum-depositing an electron transport layer, an electron injection layer, and a cathode.

[0067] The functional layers, such as the hole injection layer, hole transport layer, electron transport layer, and electron injection layer, can be added or omitted according to actual needs. With the inclusion of functional layers such as the electron injection layer, the fabricated LED device can achieve superior luminous performance.

[0068] The anode material can be ITO;

[0069] The insulating layer can be made of PMMA, and the spin coating conditions for the insulating layer can be: concentration 40-60 mg / mL, rotation speed 2000-2500 rpm / min, duration 30-45 s, annealing at 100-120℃ for 5-10 min.

[0070] The material of the hole injection layer can be PEDOT:PSS, and the spin coating conditions of the hole injection layer can be: a rotation speed of 4000-4200 rpm / min, a duration of 40-60s, and annealing at 140-150℃ for 20-30min.

[0071] The hole transport layer can be made of TFB, and the spin coating conditions for the hole transport layer can be: concentration 3-6 mg / mL, rotation speed 2000-2500 rpm / min, duration 45-60s, annealing at 100-120℃ for 20-30min.

[0072] The material of the quantum dot luminescent layer can be the quantum dots obtained in step 6, and the spin coating conditions of the quantum dot luminescent layer can be: concentration 3-6 mg / mL, rotation speed 1000-1500 rpm / min, duration 45-60s, annealing at 60-80℃ for 5-10min.

[0073] The electron transport layer can be made of TPBi and the thickness of the electron transport layer can be 60-70 nm; the electron injection layer can be made of LiF and the thickness of the electron injection layer can be 2-3 nm.

[0074] The cathode can be made of Al thin film, and the thickness of the cathode can be 100-120 nm.

[0075] As shown in Figure 5, the carrier-free light-emitting diode prepared based on Example 2 can achieve good light-emitting performance without relying on external circuitry for carrier injection.

[0076] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than those shown in the embodiments and may still achieve the desired results.

[0077] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-free light-emitting diodes, characterized in that, Includes the following steps: Step 1: Add cadmium acetate and zinc oxide to oleic acid to react, heat the reaction system to a first temperature, degas the reaction at the first temperature, then add octadecene and heat to a second temperature to obtain cadmium-zinc precursor solution; Step 2: Add sulfur powder and selenium powder to tri-n-octylphosphine for reaction, and heat the reaction system to the third temperature to obtain selenium-sulfur precursor solution; Step 3: Inject the selenium-sulfur precursor solution obtained in Step 2 into the cadmium-zinc precursor solution obtained in Step 1, maintain the reaction system at the second temperature for a period of time, and then cool it to room temperature to obtain CdSe@ZnS quantum dots; Step 4: After washing the CdSe@ZnS quantum dots obtained in Step 3 with a mixed solution of n-hexane and acetone, disperse them in the nonpolar solvent chloroform to obtain a nonpolar CdSe@ZnS quantum dot solution. Step 5: Dissolve the short-chain amino acid ligand in water to obtain an amino acid ligand solution; and add sodium hydroxide solution, zinc chloride solution, and thiourea solution to the amino acid ligand solution in sequence to obtain an aqueous solution; Step 6: Add the aqueous solution obtained in Step 5 to the nonpolar CdSe@ZnS quantum dot solution obtained in Step 4, stir, and obtain the crude aqueous CdSe@ZnS quantum dot product; Step 7: After washing the crude aqueous CdSe@ZnS quantum dot product obtained in Step 6 with ethanol, it is redispersed in deionized water to obtain aqueous CdSe@ZnS quantum dots suitable for carrier-free injection light-emitting diodes.

2. The method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-free light-emitting diodes according to claim 1, characterized in that, In step 1, the amount of cadmium acetate is 0.01-0.1 times the amount of oleic acid, the amount of zinc oxide is 0.1-0.2 times the amount of oleic acid, and the volume of octadecene is 2-3.5 times the volume of oleic acid; the first temperature is 140-160℃, and the second temperature is 280-320℃.

3. The method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-free light-emitting diodes according to claim 1, characterized in that, In step 2, the amount of sulfur powder is 0.4-0.5 times the amount of tri-n-octylphosphine, the amount of selenium powder is 0.4-0.5 times the amount of tri-n-octylphosphine, and the third temperature is 50-70℃.

4. The method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-free light-emitting diodes according to claim 1, characterized in that, In step 3, the volume of the selenium-sulfur precursor solution used is 0.08-0.12 times the volume of the cadmium-zinc precursor solution; the second temperature maintenance time is 10-25 minutes.

5. The method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-injection-free light-emitting diodes according to claim 1, characterized in that, In step 4, the concentration of the nonpolar CdSe@ZnS quantum dots is 4-6 mg / mL.

6. The method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-free light-emitting diodes according to claim 1, characterized in that, In step 5, the short-chain amino acid ligand includes any one or more combinations of glutathione, histidine, and cysteine; the concentration of the amino acid ligand solution is 0.3-1.0 mol / L; the concentration of the added sodium hydroxide solution is 0.8-1.2 mol / L, and the pH of the system after adding the sodium hydroxide solution is 12.0-13.5; the concentration of the added zinc chloride solution is 0.2-0.3 mol / L, and the volume of the added zinc chloride solution is 0.5-0.7 times the volume of the amino acid ligand solution; the concentration of the added thiourea solution is 0.2-0.3 mol / L, and the volume of the added thiourea solution is 0.5-0.7 times the volume of the amino acid ligand solution.

7. The method for preparing aqueous CdSe@ZnS quantum dots suitable for carrier-injection-free light-emitting diodes according to claim 1, characterized in that, In step 6, the volume of the nonpolar CdSe@ZnS quantum dot solution used is 0.3-0.4 times the volume of the aqueous solution, and the two phases are stirred for 4-6 hours.

8. An aqueous CdSe@ZnS quantum dot suitable for carrier-injection-free light-emitting diodes, characterized in that, It includes a luminescent core and surface ligands located on the surface of the luminescent core; the luminescent core includes oil-soluble CdSe@ZnS quantum dots; the surface ligands include short-chain amino acid ligands, wherein the short-chain amino acid ligands include any one or more combinations of glutathione, histidine, and cysteine.

9. A carrier-injection-free light-emitting diode, characterized in that, include: An anode, an insulating layer, a quantum dot light-emitting layer, and a cathode are stacked sequentially; wherein the material of the quantum dot light-emitting layer includes aqueous CdSe@ZnS quantum dots suitable for carrier-free light-emitting diodes as described in claim 8.

10. The carrier-injection-free light-emitting diode according to claim 9, characterized in that, Also includes: A first functional layer is disposed between the insulating layer and the quantum dot light-emitting layer; the first functional layer includes at least one of a hole injection layer and a hole transport layer; And / or, A second functional layer is disposed between the quantum dot light-emitting layer and the cathode; the second functional layer includes at least one of an electron injection layer and an electron transport layer. Wherein, the anode material includes indium tin oxide; or, the insulating layer material includes PMMA; or, the hole injection layer material includes PEDOT:PSS; or, the hole transport layer material includes TFB; or, the electron transport layer material includes TPBI; or, the electron injection layer material includes LiF; or, the cathode material includes an Al film.

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