CN111341942A - Electrical injection yellow light LED based on lead-free copper-based iodide and preparation method thereof - Google Patents
Electrical injection yellow light LED based on lead-free copper-based iodide and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of semiconductor light-emitting devices, and particularly relates to an electro-injection yellow light-emitting diode (LED) based on lead-free copper-based iodide and a preparation method thereof. The yellow LED comprises a transparent conductive layer, a hole injection layer, a hole transport layer, and CsCu2I3A thin film light emitting layer, an electron transport layer and a contact electrode. In one aspect of the invention, lead-free CsCu is used2I3The film is used as a luminescent layer to prepare an electrically-driven LED, so that the defect of lead toxicity of the traditional perovskite device is overcome, and the harm to human bodies and the environment is reduced; on the other hand, the spectrum of the prepared device is not changed under the condition of continuously increasing voltage (6.0-9.0 volts), and the prepared device is continuously operated for 310 minutes under the condition of 7 voltsAnd the luminous intensity is only attenuated by 50%, thus proving that the device has excellent working stability.
Description
Technical Field
The invention belongs to the technical field of semiconductor light-emitting devices, and particularly relates to an electroluminescent LED based on a lead-free copper-based halide film and a preparation method thereof.
Background
The metal halide perovskite material has excellent optical properties such as high fluorescence quantum yield, high luminescent color purity, full visible light spectral emission and the like, and shows wide application prospects in the fields of illumination, high-performance display and the like. In recent years, through diligent efforts of researchers, perovskite material-based LEDs have greatly improved luminous efficiency, and in particular, green, red and near-infrared perovskite LEDs have external quantum efficiencies of over 20%, showing great application prospects (Lu, m.; Zhang, y.; Wang, s.; Guo, j.; Yu, w.w.and Rogach, a.l, adv.funct.mater.29,1902008 (2019)). However, the light emitting layers of these perovskite devices all contain heavy metal lead, which inevitably brings about great harm to human body and environment due to the toxicity of lead ions, limiting future large-scale industrialization applications (Sun, j.; Yang, j.; Lee, j.i.; Cho, j.h. and kang.m.s.j.phys.chem.lett.9,1573-1583 (2018)). Therefore, the adoption of environmentally friendly materials is an urgent need for the development of perovskite LEDs.
Another problem to be solved in perovskite LEDs is the poor stability of device operation, especially the long-term operation of perovskite LEDs in the yellow band is challenging. In the past perovskite yellow LED reports, one generally reported that halogen perovskite CsPbBr was mixed1.88I1.22The nanocrystals are used as a light emitting layer to prepare a yellow LED (Vashishtha, P.andHalpert, J.E.chem.Mater.29,5965-5973 (2017)). However, due to the inherent halogen phase separation, the resulting device undergoes a significant change in color upon continued energization. For example, the device exhibited 558 nm yellow light at 4 volts, the red shift of the spectrum to 650 nm when the voltage was increased to 5 volts, and the spectrum split into two separate emission peaks at 665 nm and 518 nm when the voltage continued to increase to 7 volts. This is achieved byIn addition, the yellow spectrum had completely disappeared by only continuing the operation at 7 volts for 6 minutes. Therefore, the improvement of the spectral stability and the long-term working stability of the perovskite LED under different voltages has very important scientific value.
Considering the copper-based halide CsCu2I3Has the advantages of environmental protection, no toxicity and stable environment, and if CsCu can be adopted2I3The film is used as a luminescent layer, so that the preparation of the luminescent device which is environment-friendly, green and stable in work is realized, and the preparation method undoubtedly has very important scientific significance and application prospect.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an electroinjection yellow LED based on lead-free copper-based iodide and a preparation method thereof, wherein the LED adopts nontoxic and stable CsCu2I3The film is used as a luminescent layer to prepare an electrically-driven LED, and the defects of unstable operation and lead toxicity of the traditional lead-based perovskite device are overcome, so that the perovskite luminescent device which is environment-friendly and stable in work is prepared.
In order to achieve the purpose, the invention provides the following technical scheme: an electric injection yellow LED based on lead-free copper-based iodide comprises a transparent conductive substrate, wherein a hole injection layer, a hole transport layer and CsCu are sequentially arranged on the substrate2I3A thin film light emitting layer, an electron transport layer, and a contact electrode.
Preferably, the hole injection layer is polyethylene dioxythiophene-sodium polystyrene sulfonate, and the thickness of the hole injection layer is 20-30 nanometers.
Preferably, the hole transport layer is poly (4-butyl phenyl diphenylamine) or poly (9-vinyl carbazole) and has a thickness of 20-50 nm.
Preferably, the thickness of the luminescent layer is 100-150 nm; the electrode is made of a composite material of lithium fluoride and metal aluminum, and the thickness of the electrode is 100-150 nanometers.
Preferably, the electron transport layer is 1, 3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene, and the thickness of the electron transport layer is 30-50 nanometers.
The preparation method of the electrical injection yellow LED based on the lead-free copper-based iodide comprises the following steps:
(1) cleaning the transparent conductive substrate;
(2) preparing a hole injection layer on the substrate by adopting a low-temperature solution method;
(3) preparing a hole transport layer on the hole injection layer by adopting a low-temperature solution method;
(4) preparing CsCu on hole transport layer by low-temperature solution method or thermal vacuum evaporation method2I3A light emitting layer;
(5) thermal vacuum evaporation method is adopted for CsCu2I3Preparing an electron transport layer on the luminescent layer;
(6) and preparing an electrode on the electron transport layer by adopting a thermal vacuum evaporation method.
Preferably, the hole injection layer (2) in step (2) is prepared by a one-step solution method, the hole transport layer (3) in step (3) is prepared by a one-step solution method, and the CsCu in step (4)2I3The light-emitting layer (4) is prepared by a one-step solution method.
Preferably, CsCu in step (4)2I3The luminescent layer (4) is prepared by thermal vacuum evaporation method, which comprises mixing CsI and CuI powder at a molar ratio of 1: 2, uniformly grinding under the protection of inert gas, placing the ground mixture in a molybdenum boat, transferring to a thermal vacuum evaporation chamber, and placing a sample with a hole transport layer (3) at a position 30 cm above the molybdenum boat under the conditions of evaporation power of 40W and evaporation pressure of 1 × 10-4Pascal, the evaporation rate is 10-20 angstroms per second, the evaporation thickness is 110 nanometers, the substrate temperature is 100 ℃, and the evaporation time is 100 minutes; and annealing the sample after the evaporation is finished.
Preferably, the electron transport layer (5) in the step (5) is prepared by a thermal vacuum evaporation method, and the specific steps are as follows: placing 1, 3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene powder in a crucible and transferring to a thermal vacuum evaporation chamber, charging CsCu2I3The sample of the thin film luminescent layer (4) was placed upside down at a distance of 30 cm from the crucible under the conditions of an evaporation power of 30W and an evaporation pressure of 1 × 10-4Pascal, evaporation rate of 3-10 angstroms per second,the evaporation thickness was 40 nm and the evaporation time was 100 minutes.
The invention adopts nontoxic and stable CsCu2I3The film is used as a luminous layer, so that the preparation of the lead-free electroluminescent LED which is environment-friendly and stable in work is realized. On one hand, the device does not contain heavy metal lead, so that the harm to human bodies and the environment is avoided; on the other hand, the spectrum of the device is not changed under the condition of continuously increasing voltage (6.0-9.0 volts), and the luminous intensity is only attenuated by 50 percent under the condition of continuously operating for 310 minutes under the voltage of 7 volts, thereby proving that the device has excellent operation stability. Therefore, the device can simultaneously overcome the problems of unstable operation and lead toxicity of the traditional yellow perovskite LED. The invention provides a new idea for promoting the development of the perovskite LED to the direction of environmental friendliness, stable work and practicability, and has very important scientific significance.
Drawings
Fig. 1 is a schematic structural diagram of a lead-free electroluminescent LED according to the present invention.
FIG. 2 shows CsCu in example 12I3Scanning electron micrographs of the luminescent layer.
FIG. 3 shows CsCu in example 22I3Scanning electron micrographs of the luminescent layer.
Fig. 4 is a plot of current density versus voltage characteristics for the electroluminescent LEDs prepared in examples 1, 2 and 3.
Fig. 5 is a graph of the external quantum efficiency of the electroluminescent LEDs prepared in examples 1, 2 and 3.
Fig. 6 shows the electroluminescence spectra of the electroluminescent LEDs prepared in example 3 at different voltages.
Fig. 7 is a graph showing the variation of the luminous intensity of the electroluminescent LED prepared in example 3 operated continuously at 7 v.
Wherein: 1. substrate, 2. hole injection layer, 3. hole transport layer, 4.CsCu2I3Thin film luminescent layer, 5 electron transport layer, 6 contact electrode.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in figure 1, the invention provides an electric injection yellow LED based on lead-free copper-based iodide, which comprises an insulated transparent conductive substrate 1, wherein a hole injection layer 2, a hole transport layer 3 and CsCu are sequentially arranged on the substrate 12I3A thin film light-emitting layer 4, an electron transport layer 5, and a contact electrode 6.
Preferably, the transparent conductive substrate 1 is ITO conductive glass, the thickness of an ITO thin layer is 120-150 nanometers, and the resistivity is 10-3～10-4Ohm cm.
The hole injection layer 2 is polyethylene dioxythiophene-sodium polystyrene sulfonate, and the thickness of the hole injection layer is 20-30 nanometers. Among them, polyethylenedioxythiophene is also called PEDOT, and sodium polystyrene sulfonate is also called PSS.
The hole transport layer 3 is one of Poly (4-butyl phenyl diphenylamine) (namely Poly-TPD) and Poly (9-vinyl carbazole) (namely PVK), and the thickness is 20-50 nanometers.
The CsCu2I3The thickness of the thin film light-emitting layer 4 is 100-150 nm.
The electron transport layer 5 is 1, 3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene (namely TPBi), and the thickness of the electron transport layer is 30-50 nanometers.
The contact electrode 6 is made of a composite material of lithium fluoride and metal aluminum, and the thickness of the contact electrode is 100-150 nanometers.
The preparation method of the electric injection yellow LED based on the lead-free copper-based iodide comprises the following steps:
(1) cleaning the transparent conductive substrate 1;
(2) preparing a hole injection layer 2 on a substrate 1 by adopting a low-temperature solution method;
(3) preparing a hole transport layer 3 on the hole injection layer 2 by adopting a low-temperature solution method;
(4) by using a low-temperature solution method or a thermal vacuum evaporation methodPreparation of CsCu on hole transport layer 32I3A thin film light-emitting layer 4;
(5) thermal vacuum evaporation method is adopted for CsCu2I3An electron transport layer 5 is deposited on the thin film luminescent layer 4;
(6) the electrode 6 is deposited on the electron transport layer 5 using thermal vacuum evaporation.
Preferably, the hole injection layer 2 in the step (2) is prepared by a one-step solution method: filtering a PEDOT (Polytetrafluoroethylene)/PSS solution by using a water-based 0.45-micrometer nylon filter head, uniformly spin-coating the filtered solution on a transparent conductive substrate in an air environment, wherein the spin-coating conditions are as follows: and (3) carrying out high speed 3000 r/min/60 s, and finally carrying out annealing treatment on the spin-coated sample, wherein the annealing temperature is 130 ℃ and the annealing time is 20 minutes.
Preferably, the hole transport layer 3 in the step (3) is prepared according to a one-step solution method: dissolving PVK or Poly-TPD in chlorobenzene solution with the concentration of 6 milligrams per milliliter, stirring for 2 hours at the temperature of 25 ℃ by using a constant-temperature magnetic stirrer to obtain precursor solution, and uniformly spin-coating the precursor solution on a hole injection layer in a spin-coating mode under the protection of inert gas, wherein the spin-coating conditions are as follows: and (3) carrying out high speed 4000 rpm/60 seconds, and finally carrying out annealing treatment on the sample subjected to spin coating, wherein the annealing temperature is 130 ℃ and the annealing time is 20 minutes.
Preferably, CsCu in step (4)2I3The thin film light-emitting layer 4 is prepared by a low-temperature solution method or a thermal vacuum evaporation method. CscCu2I3The thin film luminescent layer 4 is prepared by a one-step solution method according to the following steps:
mixing and dissolving CsI and CuI powder into a mixed solution of dimethyl formamide and dimethyl sulfoxide (the volume ratio is 1: 1), wherein the concentration is 0.5 mol per liter, and stirring for 12 hours at 70 ℃ by using a constant-temperature magnetic stirrer to obtain a mixed solution;
under the protection of inert gas, uniformly spin-coating the mixed solution on the hole transport layer in a spin-coating mode, wherein the spin-coating conditions are as follows: 500 rpm/5 s at low speed and 3000 rpm/55 s at high speed; quickly dropping 100 microliter of toluene at 45 seconds of spin coating; and annealing the sample after the spin coating is finished, wherein the annealing temperature is 100 ℃, and the annealing time is 60 minutes.
Further, the CsCu2I3The thin film luminescent layer 4 can also be prepared by a thermal vacuum evaporation method:
CsI and CuI powders were mixed in a molar ratio of 1: 2. Under the protection of inert gas, uniformly grinding until no large particles appear;
placing the ground mixture in a molybdenum boat, transferring to a thermal vacuum evaporation chamber, and placing the sample with hole transport layer upside down at a distance of 30 cm above the molybdenum boat under the conditions of evaporation power of 40W and evaporation pressure of 1 × 10-4Pascal, the evaporation rate is 10-20 angstroms per second, the evaporation thickness is 110 nanometers, the substrate temperature is 100 ℃, and the evaporation time is 100 minutes; and (3) annealing the sample after the evaporation is finished, wherein the annealing conditions are as follows: the temperature was 100 ℃ and the environment was under vacuum for 60 minutes.
Preferably, the electron transport layer 5 in step (5) is prepared according to a thermal vacuum evaporation method:
TPBi powder is placed in a crucible and transferred to a thermal vacuum evaporation chamber, which will be charged with CsCu2I3The sample of the thin film luminescent layer was placed upside down at a distance of 30 cm from the crucible under conditions of an evaporation power of 30W and an evaporation pressure of 1 × 10-4Pascal, the evaporation rate is 3-10 angstroms per second, the evaporation thickness is 40 nanometers, and the evaporation time is 100 minutes.
The preparation method and properties of the present invention will be described below with reference to specific embodiments.
Example 1:
(1) and cleaning the transparent conductive substrate 1, wherein the adopted substrate 1 is ITO conductive glass.
ITO conductive glass is adopted as a substrate 1, and the substrate is chemically cleaned, wherein the cleaning steps are as follows: firstly, putting a substrate into a cleaning agent (Libai brand liquid detergent) to be soaked for 10 minutes, and then washing the substrate with tap water; then ultrasonic cleaning is sequentially carried out for 10 minutes by using acetone and ethanol solution respectively, and the operation is circulated once again; then washing the mixture by deionized water, and drying the mixture by high-purity nitrogen for later use.
(2) The hole injection layer 2 is prepared by a low-temperature solution method.
Placing the cleaned transparent conductive substrate 1 in an ultraviolet ozone cleaning machine for processing for 30 minutes, and spin-coating a hole injection layer on the processed transparent conductive substrate 1; PSS solution of PEDOT is filtered by a water system 0.45 micron nylon filter head, and the filtered solution is uniformly spin-coated on a transparent conductive substrate 1 in an air environment, wherein the spin-coating conditions are as follows: and (3) carrying out high speed 3000 r/min/60 s, and finally carrying out annealing treatment on the spin-coated sample, wherein the annealing temperature is 130 ℃ and the annealing time is 20 minutes. The thickness of the hole injection layer obtained was 30 nm.
(3) The hole transport layer 3 is prepared by a low-temperature solution method.
Dissolving 12 mg of PVK (Aladdin brand) powder in 2 ml of chlorobenzene solution, stirring for 2 hours at 25 ℃ by using a constant-temperature magnetic stirrer to obtain a precursor solution, transferring the prepared sample of the hole injection layer and the precursor solution into an inert gas-protected glove box, and uniformly spin-coating the precursor solution on the hole injection layer in a spin-coating manner, wherein the spin-coating conditions are as follows: the spin-coated samples were annealed at a high speed of 4000 rpm/60 seconds in a glove box at 130 ℃ for 20 minutes. The thickness of the obtained hole transport layer was 40 nm.
(4) CsCu prepared by one-step solution method2I3A thin film light-emitting layer 4.
Firstly, 0.26 g of CsI (Aladdin brand) and 0.38 g of CuI (Aladdin brand) powder are dissolved in a mixed solution of 1 ml of dimethylformamide and 1 ml of dimethyl sulfoxide; then stirring for 12 hours at 70 ℃ by using a constant-temperature magnetic stirrer; and then uniformly spin-coating the prepared mixed solution on the hole transport layer in a glove box protected by inert gas in a spin-coating mode, wherein the spin-coating conditions are as follows: 500 rpm/5 s at low speed and 3000 rpm/55 s at high speed; quickly dropping 100 microliter of toluene at 45 seconds of spin coating; and annealing the sample after the spin coating is finished, wherein the annealing temperature is 100 ℃, and the annealing time is 60 minutes. CsCu prepared2I3The thickness of the thin film light emitting layer is 110 nm.
FIG. 2 shows CsCu prepared by one-step solution method2I3Sweeping of the thin-film luminescent layer 4Scanning electron micrographs.
(5) Spin-coating CsCu2I3And a sample of the thin film luminescent layer 4 is placed in a vacuum evaporation chamber, and the preparation of the electron transport layer 5 is completed by adopting a thermal vacuum evaporation method.
The method comprises the following specific steps: 2 g of TPBi (Aladdin brand) powder are first placed in a crucible, then loaded with CsCu2I3The sample of the thin film luminescent layer is inversely placed at a position 30 cm above the crucible, the mechanical pump is started to vacuumize the evaporation chamber, when the vacuum degree of the chamber is lower than 5 pascals, the molecular pump is started to continue vacuuming until the vacuum degree of the chamber is lower than 1.0 × 10-4Starting evaporation at Pascal, setting the power to be 30 watts, the evaporation rate to be 3-10 angstroms per second, the evaporation thickness to be 40 nanometers, and the evaporation time to be 100 minutes. The thickness of the prepared electron transport layer was 40 nm.
(6) And depositing lithium fluoride (Aladdin) and an aluminum electrode on the surface of the electron transmission layer 5 by adopting a thermal vacuum evaporation method and combining a mask plate, wherein the thicknesses of the lithium fluoride and the aluminum electrode are respectively 1 nanometer and 100 nanometers.
Example 2:
(1) ITO conductive glass is used as the substrate 1. The method of cleaning the transparent conductive substrate 1 in this embodiment is the same as that in embodiment 1.
(2) The hole injection layer 2 is prepared by a low-temperature solution method. The process and preparation parameters in this section are the same as in example 1.
(3) The hole transport layer 3 is prepared by a low-temperature solution method. The process and preparation parameters in this section are the same as in example 1.
(4) CsCu prepared by thermal vacuum evaporation method2I3Thin film light-emitting layer 4: firstly, 1.95 g of CsI (Aladdin brand) and 2.85 g of CuI (Aladdin brand) powder are mixed, and then the mixture is uniformly ground in a glove box protected by inert gas until no large particles appear;
placing the grinded mixture of 4.8 g in a molybdenum boat and transferring to a thermal vacuum evaporation chamber, placing a sample with a hole transport layer at a position 30 cm above the molybdenum boat, starting a mechanical pump, vacuumizing the evaporation chamber, and when the vacuum degree of the chamber is highAfter the vacuum degree of the cavity is lower than 5 pascals, starting the molecular pump to continuously pump vacuum until the vacuum degree of the cavity is lower than 1.0 × 10-4Starting evaporation at Pascal, setting the power to 40 watts, the evaporation rate to 10-20 angstroms per second, the evaporation thickness to 110 nanometers, the substrate temperature to 100 ℃, and the evaporation time to 100 minutes. CsCu prepared2I3The thin film luminescent layer is 110 nanometers; and (3) annealing the sample after the evaporation is finished, wherein the annealing conditions are as follows: the temperature was 100 ℃ and the environment was under vacuum for 60 minutes.
FIG. 3 shows the preparation of CsCu by thermal vacuum deposition2I3Scanning electron micrographs of the thin-film luminescent layer 4.
(5) The electron transport layer 5 was prepared by thermal vacuum evaporation. The process and preparation parameters in this section are the same as in example 1.
(6) Finally, the contact electrode 6 is prepared by a thermal vacuum evaporation method. The process and preparation parameters in this section are the same as in example 1.
The difference between this example and example 1 is that CsCu2I3The thin-film luminescent layer 4 adopts a thermal vacuum evaporation method, so that the evaporation power and the evaporation rate of the mixture can be controlled for CsCu2I3The crystal quality of the thin film light emitting layer 4 is regulated. Further, CsCu prepared by using the method of the present example and the method of example 12I3Thin film light emitting layer, the performance of the device versus the example is shown in fig. 5.
Example 3:
(1) ITO conductive glass is used as the substrate 1. The method of cleaning the transparent conductive substrate 1 in this embodiment is the same as that in embodiment 1.
(2) The hole injection layer 2 is prepared by a low-temperature solution method. The process and preparation parameters in this section are the same as in example 1.
(3) Preparing the hole transport layer 3 by using a low-temperature solution method: dissolving 18 mg of Poly-TPD (Aladdin) powder in 3 ml of chlorobenzene solution, stirring for 2 hours at 25 ℃ by using a constant-temperature magnetic stirrer to obtain a precursor solution, transferring the prepared sample of the hole injection layer and the precursor solution into an inert gas-protected glove box, and uniformly spin-coating the precursor solution on the hole injection layer in a spin-coating manner, wherein the spin-coating conditions are as follows: the spin-coated samples were annealed at a high speed of 4000 rpm/60 seconds in a glove box at 130 ℃ for 20 minutes. The thickness of the obtained hole transport layer was 40 nm.
(4) CsCu prepared by one-step solution method2I3A thin film light-emitting layer 4. The process and preparation parameters in this section are the same as in example 1.
(5) The electron transport layer 5 was prepared by thermal vacuum evaporation. The process and preparation parameters in this section are the same as in example 1.
(6) Finally, the contact electrode 6 is prepared by a thermal vacuum evaporation method. The process and preparation parameters in this section are the same as in example 1.
This example is different from example 1 in that the hole transport layer is Poly-TPD, and that Poly-TPD and PVK have different conductivities and carrier mobilities, when they are respectively different from CsCu2I3When the thin film light-emitting layer 4 is contacted, CsCu can be realized2I3The thin film light-emitting layer 4 has different hole injection effects.
Fig. 4 is a graph of current density versus voltage characteristics of the devices prepared in examples 1, 2, and 3, all of which exhibit significant rectifying characteristics. Showing that all three embodiments can be realized with CsCu2I3An electroluminescent LED with a thin film light emitting layer.
Fig. 5 is a comparison of external quantum efficiency of the devices prepared in examples 1, 2, 3. As can be seen from the figure, the external quantum efficiency of the electroluminescent LED prepared in example 1 is 0.10%, the device in example 2 has the lowest external quantum efficiency of 0.07%, and the device in example 3 has the highest external quantum efficiency of 0.17%.
Fig. 6 shows the electroluminescence spectra of the electroluminescent LEDs prepared in example 3 at different voltages. It can be seen from the figure that under different voltages, the shape and position of the spectrum are not changed, the spectrum shows excellent spectral stability, and is obviously superior to the traditional CsPbBr1.88I1.22The result of the light emitting device.
Fig. 7 is a graph of the variation of the luminous intensity of the electroluminescent LED prepared in example 3 continuously operated at 7 v, and it can be seen from the graph that the luminous intensity is attenuated by only 50% for 310 min continuously operated at 7 v, and the excellent operation stability is exhibited.
In one aspect of the invention, lead-free CsCu is used2I3The film is used as a luminescent layer to prepare an electrically-driven LED, so that the defect of lead toxicity of the traditional perovskite device is overcome, and the harm to human bodies and the environment is reduced; on the other hand, the spectrum of the prepared device is not changed under the condition of continuously increasing voltage (6.0-9.0 volts), the device is continuously operated for 310 minutes under the condition of 7 volts, the luminous intensity is only attenuated by 50 percent, and the device is proved to have excellent operation stability.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. An electro-injection yellow LED based on lead-free copper-based iodide, comprising a transparent conductive substrate (1), characterized in that: a hole injection layer (2), a hole transport layer (3) and CsCu are arranged on the substrate (1) in sequence2I3A thin film light-emitting layer (4), an electron transport layer (5), and a contact electrode (6).
2. The lead-free copper-based iodide based electro-injection yellow LED of claim 1, wherein: the hole injection layer (2) is polyethylene dioxythiophene-sodium polystyrene sulfonate, and the thickness of the hole injection layer is 20-30 nanometers.
3. The lead-free copper-based iodide based electro-injection yellow LED of claim 1, wherein: the hole transport layer (3) is poly (4-butyl phenyl diphenylamine) or poly (9-vinyl carbazole) and has a thickness of 20-50 nanometers.
4. The lead-free copper-based iodide based electro-injection yellow LED of claim 1, wherein: the thickness of the luminous layer (4) is 100-150 nm; the electrode (6) is a composite material of lithium fluoride and metal aluminum, and the thickness of the electrode is 100-150 nanometers.
5. The lead-free copper-based iodide based electro-injection yellow LED of claim 1, wherein: the electron transport layer (5) is 1, 3, 5-tri (1-phenyl-1H-benzimidazole-2-yl) benzene, and the thickness of the electron transport layer is 30-50 nanometers.
6. The method for preparing the lead-free copper-based iodide based electro-injection yellow LED according to any one of claims 1 to 5, which is characterized by comprising the following steps:
(1) cleaning a transparent conductive substrate (1);
(2) preparing a hole injection layer (2) on a substrate (1) by adopting a low-temperature solution method;
(3) preparing a hole transport layer (3) on the hole injection layer (2) by adopting a low-temperature solution method;
(4) preparing CsCu on the hole transport layer (3) by adopting a low-temperature solution method or a thermal vacuum evaporation method2I3A light-emitting layer (4);
(5) thermal vacuum evaporation method is adopted for CsCu2I3Preparing an electron transport layer (5) on the luminescent layer (4);
(6) and preparing an electrode (6) on the electron transport layer (5) by adopting a thermal vacuum evaporation method.
7. The method for preparing the lead-free copper-based iodide based electro-injection yellow LED according to claim 6, wherein the method comprises the following steps: the cavity injection layer (2) in the step (2) is prepared by adopting a one-step solution method, the cavity transmission layer (3) in the step (3) is prepared by adopting a one-step solution method, and CsCu in the step (4)2I3The light-emitting layer (4) is prepared by a one-step solution method.
8. The method for preparing the leadless copper-based iodide based electro-injection yellow LED according to the claim 6, wherein the CsCu in the step (4)2I3The luminescent layer (4) is prepared by adopting a thermal vacuum evaporation method, and the method comprises the following specific steps:
mixing CsI powder and CuI powder at a molar ratio of 1: 2, uniformly grinding under the protection of inert gas, placing the ground mixture in a molybdenum boat, transferring the mixture to a thermal vacuum evaporation chamber, and placing a sample with a hole transport layer (3) at a position 30 cm above the molybdenum boat under the conditions of evaporation power of 40W and evaporation pressure of 1 × 10-4Pascal, the evaporation rate is 10-20 angstroms per second, the evaporation thickness is 110 nanometers, the substrate temperature is 100 ℃, and the evaporation time is 100 minutes; and annealing the sample after the evaporation is finished.
9. The method for preparing the electroluminescent LED based on the lead-free copper-based halide thin film according to claim 6, wherein the electron transport layer (5) in the step (5) is prepared by a thermal vacuum evaporation method, and the method comprises the following specific steps:
placing 1, 3, 5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene powder in a crucible and transferring to a thermal vacuum evaporation chamber, charging CsCu2I3The sample of the thin film luminescent layer (4) was placed upside down at a distance of 30 cm from the crucible under the conditions of an evaporation power of 30W and an evaporation pressure of 1 × 10-4Pascal, the evaporation rate is 3-10 angstroms per second, the evaporation thickness is 40 nanometers, and the evaporation time is 100 minutes.
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