An alkali ion passivated lead-free perovskite light emitting diode and a preparation method thereof

Abstract

The application discloses an alkali ion passivated non-lead perovskite light-emitting diode and a preparation method thereof, and belongs to the technical field of light-emitting diodes.The light-emitting diode comprises, from bottom to top, ITO conductive glass, a hole injection layer, a hole transport layer, a non-lead perovskite light-emitting layer, an electron transport layer, an electrode modification layer and a metal electrode.The application further provides a preparation method of the non-lead perovskite light-emitting diode.The non-lead perovskite light-emitting layer is prepared by an anti-solvent crystallization method from an alkali ion passivated non-lead perovskite precursor solution and an anti-solvent, and the alkali ion is introduced to inhibit non-radiative recombination loss in a surface and a grain boundary of the non-lead perovskite thin film, so that the light-emitting efficiency is enhanced, and the photoelectric performance of the non-lead perovskite light-emitting diode device is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of light-emitting diodes, and particularly relates to an alkali ion passivated non-lead perovskite light-emitting diode and a preparation method thereof. BACKGROUND

[0002] Perovskite materials have become star materials in the field of light emission due to their advantages of continuous tunable emission wavelength, narrow half-peak width, high color purity, high quantum yield, low cost and easy solution processing.

[0003] Since the first perovskite light-emitting diode was proposed in 2014, researchers have improved the performance of perovskite light-emitting diodes through material component modulation, defect passivation engineering and device structure optimization. However, the traditional perovskite material contains heavy metal lead, which will have adverse effects on the environment. Considering the sustainability of environmental development, it is necessary to further explore non-lead and stable perovskite light-emitting diodes. The main obstacle in the development of non-lead perovskite light-emitting diodes is that solution processing leads to a large number of defects in the perovskite film, and the non-radiative recombination of carriers caused thereby is the main way of charge and energy loss, which limits the performance of perovskite light-emitting diodes.

[0004] Therefore, how to reduce the defects of the perovskite film through certain defect passivation strategies, and inhibit non-radiative recombination to improve the luminous efficiency and stability of non-lead perovskite light-emitting diodes, is a technical problem to be solved in the technical field. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide an alkali ion passivated non-lead perovskite light-emitting diode and a preparation method thereof.

[0006] The present application provides a non-lead perovskite light-emitting diode based on alkali ion passivation strategy, which comprises, from bottom to top, ITO conductive glass, hole injection layer, hole transport layer, non-lead perovskite light-emitting layer, electron transport layer, electrode modification layer and metal electrode.

[0007] The non-lead perovskite light-emitting layer is a non-lead perovskite film prepared from alkali ion passivated non-lead perovskite precursor solution and antisolvent.

[0008] Further, the thickness of the ITO conductive glass is 80-200 nm, the thickness of the hole injection layer is 1-100 nm, the thickness of the hole transport layer is 1-100 nm, the thickness of the non-lead perovskite light-emitting layer is 1-150 nm, the thickness of the electron transport layer is 1-100 nm, the thickness of the electrode modification layer is 1-10 nm, and the thickness of the metal electrode is 50-200 nm.

[0009] A preparation method of an alkali ion passivated non-lead perovskite light emitting diode, comprising the following steps:

[0010] After the ITO conductive glass is cleaned, the hole injection layer solution is filtered, and is spin-coated on the surface of the clean ITO conductive glass, and is cooled to room temperature after annealing;

[0011] Then, the hole transport layer solution is configured, the hole transport layer solution is spin-coated on the surface of the hole injection layer obtained above, and is cooled to room temperature after annealing;

[0012] Subsequently, the alkali ion passivated non-lead perovskite precursor solution is configured, the alkali ion passivated non-lead perovskite precursor solution is filtered through a polytetrafluoroethylene filter head, and is spin-coated on the surface of the hole transport layer, wherein a rapid drop of an anti-solvent is added to the spin-coated surface at 30-60 seconds of spin-coating, and then is cooled to room temperature after annealing;

[0013] Next, the electron transport layer is evaporated on the surface of the non-lead perovskite light emitting layer obtained above, and the electrode modification layer is evaporated on the surface of the non-lead perovskite light emitting layer.

[0014] Finally, the metal electrode is evaporated on the surface of the electrode modification layer, and the non-lead perovskite light emitting diode based on the alkali ion passivation strategy is obtained.

[0015] Further, the hole injection layer solution is any one of (3,4-ethylenedioxythiophene): poly(styrenesulfonate), cuprous thiocyanate and nickel oxide.

[0016] Further, the hole transport layer solution is any one of poly[N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine], poly(9-vinylcarbazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4'-(N-(4-n-butyl)phenyl)-diphenylamine)], poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazole-4,8-diyl)], poly(9,9-dioctylfluorene-2,7-diyl)-alt-(N,N'-diphenylphenylamine-N,N'-diyl), 4,4'-bis(9-carbazolyl)biphenyl and 4,4',4''-tris(carbazol-9-yl)triphenylamine, which is solid, is dissolved in any one of chlorobenzene, chloroform and toluene to prepare the hole transport layer solution at a concentration of 1-50 mg / mL.

[0017] Further, the alkali ion passivated non-lead perovskite precursor solution is a solution of alkali ions Li + , Na + , K +Any one of the following: cesium iodide, cuprous iodide, cesium chloride, cuprous chloride, cesium bromide, cuprous bromide, bismuth bromide, bismuth chloride, antimony bromide, antimony chloride, tin tetrabromide and tin tetrachloride, is dissolved in one or both of N,N-dimethylformamide and dimethyl sulfoxide to configure.

[0018] Further, the alkali ion Li + , Na + , K + Any one of the following accounts for 0% to 20% of the total solution solid mass percentage.

[0019] Further, the anti-solvent is any one of toluene, chlorobenzene, methyl acetate and ethyl acetate.

[0020] Further, the electron transport layer material is any one of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 4,6-bis(3,5-di(2-pyridyl)phenyl)-2-methylpyrimidine, 4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine, 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene and 2,4,6-tris[3-(diphenylphosphoryl)phenyl]-1,3,5-triazole.

[0021] Further, the electrode modification layer material is any one of lithium fluoride and 8-hydroxyquinoline-lithium, and the metal electrode material is any one of aluminum and silver.

[0022] Advantages of the present application:

[0023] 1. The light-emitting layer of the non-lead perovskite light-emitting diode is a non-lead perovskite thin film prepared by an anti-solvent crystallization method from an alkali ion passivated non-lead perovskite precursor solution and an anti-solvent, which enhances ion migration by introducing alkali ions to suppress non-radiative recombination loss in the surface and grain boundary of the non-lead perovskite thin film, thereby improving not only the light-emitting efficiency of the non-lead perovskite material but also the photoelectric performance of the light-emitting diode device.

[0024] 2. The non-lead perovskite light-emitting diode is different from the traditional perovskite light-emitting diode in that it does not contain the harmful lead element to the environment, thus being more environmentally friendly and conducive to the sustainable development of the environment.

[0025] 3. The non-lead perovskite light-emitting diode is prepared by a solution method, which is simple, low in cost, easy to operate and good in repeatability, and is conducive to subsequent industrialized production. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, for those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0027] Figure 1 is a device structure schematic diagram of the non-lead perovskite light-emitting diode described in the present application;

[0028] Figure 2 is an electroluminescence curve (EL) diagram of the non-lead perovskite light-emitting diode device of the embodiment 1 and the comparative example 1 of the present application;

[0029] Figure 3 is a luminance-voltage (Luminance-V) diagram of the non-lead perovskite light-emitting diode device of the embodiment 1 and the comparative example 1 of the present application;

[0030] Figure 4 is a current density-voltage (J-V) diagram of the non-lead perovskite light-emitting diode device of the embodiment 2 and the comparative example 2 of the present application;

[0031] Figure 5 is an external quantum efficiency-voltage (EQE-V) diagram of the non-lead perovskite light-emitting diode device of the embodiment 2 and the comparative example 2 of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the scope of protection of the present application.

[0033] The non-lead perovskite light-emitting diode based on alkali ion passivation strategy described in the present application comprises, from bottom to top, ITO conductive glass, hole injection layer, hole transport layer, non-lead perovskite light-emitting layer, electron transport layer, electrode modification layer, and metal electrode, wherein the thickness of the ITO conductive glass is 80-200 nm, the thickness of the hole injection layer is 1-100 nm, the thickness of the hole transport layer is 1-100 nm, the thickness of the non-lead perovskite light-emitting layer is 1-150 nm, the thickness of the electron transport layer is 1-100 nm, the thickness of the electrode modification layer is 1-10 nm, and the thickness of the metal electrode is 50-200 nm, as shown in Figure 1The main working principle is that under the applied bias, on the one hand, electrons are injected from the cathode of the device, flow through the electron transport layer to the perovskite light-emitting layer; on the other hand, holes are injected from the anode of the device, flow through the hole injection layer and the hole transport layer to the perovskite light-emitting layer, and the above-mentioned electrons and holes meet in the perovskite light-emitting layer and recombine to emit light. However, due to the inherent defects of the non-lead perovskite thin film, the non-radiative recombination centers introduced by the non-lead perovskite thin film have a bad influence on the carrier transport, which limits the performance of the non-lead perovskite light-emitting diode. Previously, the defect passivation strategy has been proved to effectively improve the radiative recombination of carriers in the perovskite. The alkali ion is introduced to suppress the non-radiative energy loss of the non-lead perovskite, and the alkali doping eliminates the trap states in the non-lead perovskite, prolongs the lifetime of the carriers, reduces the leakage current, and finally greatly improves the luminous efficiency of the non-lead perovskite light-emitting diode.

[0034] Example 1

[0035] (1) The ITO conductive glass with a thickness of 150 nm was ultrasonically cleaned with detergent, deionized water, acetone and isopropyl alcohol respectively, and the ultrasonic time was 15 minutes;

[0036] (2) The cleaned ITO conductive glass was blown dry and placed in a ultraviolet ozone machine for 30 minutes;

[0037] (3) 100 uL of PEDOT:PSS solution was filtered through a water phase filter head with a pore size of 0.22 pm, and then spin-coated on the surface of the ITO conductive glass obtained in step (2) at a rotation speed of 4000 revolutions / minute for 40 seconds, and then annealed at 140 DEG C for 20 minutes, and then cooled to room temperature;

[0038] (4) 6 mg of Poly-TPD solid was weighed using a balance and dissolved in 1 mL of chlorobenzene, and stirred at 70 DEG C for 10 h until completely dissolved, to obtain a hole transport layer solution with a concentration of 6 mg / mL; 100 uL of the hole transport layer solution was spin-coated on the surface of the hole injection layer obtained in step (3) at a rotation speed of 3000 revolutions / minute for 45 seconds, and then annealed at 130 DEG C for 15 minutes, and then cooled to room temperature;

[0039] (5) Weigh 10.68 mg of KI solid, 43.3 mg of CsI solid and 63.5 mg of CuI solid using a balance and dissolve them in 1 mL of DMSO. Stir the solution at 60 °C for 12 h until completely dissolved to obtain an alkali-passivated lead-free perovskite precursor solution. Place the hole transport layer surface obtained in step (4) in an ultraviolet ozone generator for 10 minutes. Filter 150 μL of the alkali-passivated lead-free perovskite precursor solution through a 0.45 μm polytetrafluoroethylene filter and spin-coat it onto the surface of the hole transport layer after ultraviolet ozone treatment at a first rotation speed of 100 rpm for 10 seconds and a second rotation speed of 3000 rpm for 60 seconds. Add 100 L of toluene as an anti-solvent to the spin-coated surface at the 45th second of spin coating. Then anneal at 90 °C for 60 minutes and cool to room temperature.

[0040] (6) When the pressure is <6×10 -4 Under the condition of Pa, the surface of the lead-free perovskite luminescent layer obtained in step (5) is... The growth rate of TPBi with a thickness of 35 nm was achieved by vapor deposition.

[0041] (7) When the pressure is <6×10 -4 Under the condition of Pa, the surface of the electron transport layer obtained in step (6) is... The growth rate is 1 nm of LiF vapor deposition;

[0042] (8) When the pressure is <6×10 -4 Under the condition of Pa, the surface of the electrode modification layer obtained in step (7) is By evaporating Ag at a growth rate of 120 nm, a lead-free perovskite light-emitting diode based on an alkali ion passivation strategy is obtained.

[0043] Comparative Example 1

[0044] (1) Same as step (1) in Example 1;

[0045] (2) Dry the cleaned ITO conductive glass and place it in an ultraviolet ozone generator for 45 minutes;

[0046] (3) After filtering 80 μL of PEDOT:PSS solution through a 0.22 μm aqueous filter, spin-coat it onto the surface of the ITO conductive glass obtained in step (2) at a speed of 3000 rpm for 40 seconds, and then anneal it at 120 °C for 15 minutes, and then cool it to room temperature.

[0047] (4) using a balance to weigh 8 mg of PVK solid to be dissolved in 1 mL of chloroform, which is stirred at 80°C for 10 h until completely dissolved, i.e. to obtain a hole transport layer solution with a concentration of 8 mg / mL; 90 uL of the hole transport layer solution is spin-coated on the surface of the hole injection layer obtained in step (3) at a rotation speed of 2500 revolutions / minute for 45 seconds, and then annealed at 110°C for 10 minutes, and then cooled to room temperature;

[0048] (5) using a balance to weigh 43.3 mg of CsI solid and 63.5 mg of CuI solid respectively to be dissolved in 1 mL of DMSO, which is stirred at 60°C for 10 h until completely dissolved, i.e. to obtain a non-lead perovskite precursor solution; the surface of the hole transport layer obtained in step (4) is placed in an ultraviolet ozone machine for a treatment time of 10 minutes; 120 uL of the non-lead perovskite precursor solution is filtered through a polytetrafluoroethylene filter head with a pore size of 0.45 pm, and then spin-coated on the surface of the ultraviolet ozone-treated hole transport layer at a first rotation speed of 300 revolutions / minute for 5 seconds, and a second rotation speed of 4000 revolutions / minute for 60 seconds, wherein 100 uL of ethyl acetate is quickly added to the surface being spin-coated at the 40th second as an anti-solvent; then annealed at 100°C for 40 minutes, and then cooled to room temperature;

[0049] (6) the same as step (6) of Example 1;

[0050] (7) the same as step (7) of Example 1;

[0051] (8) 100 nm of Al is evaporated on the surface of the electrode modification layer obtained in step (7) at a growth rate of 0.1 A / s under the condition of a pressure < 6 x 10 -4 Pa, i.e. to obtain a non-lead perovskite light-emitting diode.

[0052] Example 2

[0053] (1) a detergent, deionized water, acetone and isopropyl alcohol are respectively used to ultrasonically clean ITO conductive glass with a thickness of 120 nm, and the ultrasonic cleaning time is 10 minutes;

[0054] (2) the cleaned ITO conductive glass is blown dry and placed in an ultraviolet ozone machine for a treatment time of 20 minutes;

[0055] (3) 100 uL of the PEDOT:PSS solution is filtered through a water phase filter head with a pore size of 0.22 pm, and then spin-coated on the surface of the ITO conductive glass obtained in step (2) at a rotation speed of 4000 revolutions / minute for 60 seconds, and then annealed at 120°C for 20 minutes, and then cooled to room temperature;

[0056] ​(4) using a balance to weigh 10 mg of TFB solid to be dissolved in 1 mL of n-octane, which is stirred at 75 °C for 10 h until completely dissolved, i.e. to obtain a hole transport layer solution with a concentration of 10 mg / mL; 100 uL of the hole transport layer solution is spin-coated on the surface of the hole injection layer obtained in step (3) at a rotation speed of 3500 revolutions / minute for 45 seconds, and then annealed at 130 °C for 15 minutes, followed by cooling to room temperature;

[0057] (5) using a balance to weigh 15.4 mg of LiBr solid, 63.8 mg of CsBr solid and 89.7 mg of BiBr3 solid respectively to be dissolved in 1 mL of DMF, which is stirred at 70 °C for 12 h until completely dissolved, i.e. to obtain an alkali ion passivated non-lead perovskite precursor solution; the surface of the hole transport layer obtained in step (4) is placed in an ultraviolet ozone machine for a treatment time of 10 minutes; 150 uL of the alkali ion passivated non-lead perovskite precursor solution is filtered through a polytetrafluoroethylene filter head with a pore size of 0.45 pm, and then spin-coated on the surface of the ultraviolet ozone treated hole transport layer at a first rotation speed of 100 revolutions / minute for 5 seconds, and a second rotation speed of 4000 revolutions / minute for 45 seconds, wherein 80 L of toluene is quickly added to the surface being spin-coated as an anti-solvent at the 35th second of the spin-coating; then annealed at 80 °C for 60 minutes, followed by cooling to room temperature;

[0058] (6) under the condition of a pressure < 6 x 10-4Pa, 40 nm thick TmPyPB is evaporated on the surface of the non-lead perovskite light-emitting layer obtained in step (5) at a growth rate of ;

[0059] (7) under the condition of a pressure < 6 x 10-4Pa, 1.2 nm thick Liq is evaporated on the surface of the electron transport layer obtained in step (6) at a growth rate of ;

[0060] (8) under the condition of a pressure < 6 x 10-4Pa, 100 nm thick Ag is evaporated on the surface of the electrode modification layer obtained in step (7) at a growth rate of , i.e. to obtain a non-lead perovskite light-emitting diode based on an alkali ion passivation strategy.

[0061] Comparative Example 2

[0062] (1) the same as step (1) of Example 2;

[0063] (2) the cleaned ITO conductive glass is blown dry and placed in an ultraviolet ozone machine for a treatment time of 25 minutes;

[0064] (3) 80 uL of PEDOT:PSS solution was filtered through a water phase filter head with a pore size of 0.22 pm, and then spin-coated on the surface of ITO conductive glass obtained in step (2) at a rotation speed of 3000 rpm for 60 s, followed by annealing at 100 °C for 15 min, and then cooling to room temperature;

[0065] (4) 12 mg of TCTA solid was weighed using a balance and dissolved in 1 mL of n-octane, which was stirred at 80 °C for 10 h until completely dissolved, thereby obtaining a hole transport layer solution with a concentration of 12 mg / mL; 90 uL of the hole transport layer solution was spin-coated on the surface of the hole injection layer obtained in step (3) at a rotation speed of 3000 rpm for 45 s, followed by annealing at 110 °C for 10 min, and then cooling to room temperature;

[0066] (5) 63.8 mg of CsBr solid and 89.7 mg of BiBr3 solid were weighed using a balance respectively and dissolved in 1 mL of DMF, which was stirred at 70 °C for 10 h until completely dissolved, thereby obtaining a non-lead perovskite precursor solution; the surface of the hole transport layer obtained in step (4) was placed in an ultraviolet ozone machine for 10 min; 120 uL of the non-lead perovskite precursor solution was filtered through a polytetrafluoroethylene filter head with a pore size of 0.45 pm, and then spin-coated on the surface of the hole transport layer treated by ultraviolet ozone at a first rotation speed of 500 rpm for 5 s and a second rotation speed of 5000 rpm for 45 s, wherein 80 uL of toluene was quickly added to the surface being spin-coated at the 30th second; followed by annealing at 90 °C for 40 min, and then cooling to room temperature;

[0067] (6) The same as step (6) of Example 2;

[0068] (7) The same as step (7) of Example 2;

[0069] (8) 80 nm of Al was evaporated on the surface of the electrode modification layer obtained in step (7) at a growth rate of 0.1 A / s under the condition of a pressure < 6 x 10 -4 Pa, thereby obtaining a non-lead perovskite light-emitting diode.

[0070] Device performance test:

[0071] The photoelectric performance of the non-lead perovskite light-emitting diodes of Example 1 and Comparative Example 1 was tested by using a Keithley 2600 series source meter, a complex optical PG2000-Pro spectrometer, and a KONICA MINOLTA LS-110 type luminance meter, and the test results are shown in Figure 2 and Figure 3 .

[0072] ​Reference is made to Figure 2 , Figure 2 is the electroluminescence curve (EL) of the non-lead perovskite light-emitting diode device of Example 1 and Comparative Example 1. At the same driving voltage (5V), the electroluminescence intensity of the device after alkali ion passivation (Example 1) is higher than that of the device without alkali ion passivation (Comparative Example 1), indicating that the alkali ion passivation strategy can effectively improve the electro-optical conversion efficiency of the device. In addition, the peak of the electroluminescence curve of both is near 575 nm, which is within the standard yellow emission wavelength (570-585 nm) range, indicating that the alkali ion passivation strategy does not affect the color purity of the electroluminescence of the device.

[0073] Reference is made to Figure 3 , Figure 3 is the luminance-voltage (Luminance-V) curve of the non-lead perovskite light-emitting diode device of Example 1 and Comparative Example 1. When the device reaches the turn-on voltage (luminance of 1 cd / m 2 After that, the luminance of the device after alkali ion passivation (Example 1) is higher than that of the device without alkali ion passivation (Comparative Example), because the added alkali ions in the perovskite light-emitting diode of Example 1 improve the coincidence efficiency of the carriers, reduce the current leakage, and more holes from the hole transport layer and electrons from the electron transport layer recombine in the perovskite light-emitting layer to emit photons under a certain voltage, thereby improving the luminance.

[0074] The non-lead perovskite light-emitting diode of Example 2 and Comparative Example 2 was tested for photoelectric performance using a Keithley 2400 series source meter and a KONICA MINOLTA CS-2000A spectroradiometric luminance meter, and the test results are shown in Figure 4 and Figure 5 .

[0075] Reference is made to Figure 4 , Figure 4 is the current density-voltage (J-V) curve of the non-lead perovskite light-emitting diode device of Example 2 and Comparative Example 2. At the same driving voltage, the current density of the device after alkali ion passivation (Example 2) is much smaller than that of the device without alkali ion passivation (Comparative Example 2), which means a higher surface coverage, indicating that the alkali ion passivation strategy effectively suppresses the non-radiative recombination of the perovskite thin film, reduces the leakage current of the device at the working voltage, and thus significantly improves the luminous efficiency of the device.

[0076] Reference is made to Figure 5 , Figure 5The external quantum efficiency-voltage (EQE-V) plot of the non-lead perovskite light-emitting diode device of Example 2 and Comparative Example 2 of the present application. For a light-emitting diode, its external quantum efficiency is equal to the ratio of the number of photons emitted in the plane per unit time to the number of electron-hole pairs injected in the plane per unit time. Higher external quantum efficiency proves that the number of electron-hole pair recombination per unit time is more, which is due to the better quality of the thin film formed. The EQE of the device passivated by alkali ions (Example 2) is higher than that of the device not passivated by alkali ions (Comparative Example 2), indicating that the alkali ion passivation strategy can enhance the recombination efficiency of carriers, thereby improving the optoelectronic performance of the non-lead perovskite light-emitting diode.

[0077] In the description of the present specification, the description referring to the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Also, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0078] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. An alkali-ion passivated lead-free perovskite light-emitting diode, characterized in that, The diode, from bottom to top, comprises ITO conductive glass, a hole injection layer, a hole transport layer, a lead-free perovskite light-emitting layer, an electron transport layer, an electrode modification layer, and a metal electrode. The lead-free perovskite light-emitting layer is a lead-free perovskite film, which is prepared by an alkali-ion passivated lead-free perovskite precursor solution and an anti-solvent. Specifically, the alkali-ion passivated lead-free perovskite precursor solution is filtered through a polytetrafluoroethylene filter and then spin-coated onto the surface of the hole transport layer. During the 30th to 60th second of spin-coating, the anti-solvent is rapidly added to the spin-coated surface, and then annealed and cooled to room temperature. The alkali-passivated lead-free perovskite precursor solution is composed of alkali ions. , , Any one of the following can be prepared by dissolving any two solids selected from cesium iodide, cuprous iodide, cesium chloride, cuprous chloride, cesium bromide, cuprous bromide, bismuth bromide, bismuth chloride, antimony bromide, antimony chloride, tin tetrabromide, and tin tetrachloride in one or two of N,N-dimethylformamide and dimethyl sulfoxide. The hole injection layer solution used is (3,4-ethylenedioxythiophene):poly(styrene sulfonate).

2. The alkali-ion passivated lead-free perovskite light-emitting diode according to claim 1, characterized in that, The thickness of the ITO conductive glass is 80–200 nm, the thickness of the hole injection layer is 1–100 nm, the thickness of the hole transport layer is 1–100 nm, the thickness of the lead-free perovskite light-emitting layer is 1–150 nm, the thickness of the electron transport layer is 1–100 nm, the thickness of the electrode modification layer is 1–10 nm, and the thickness of the metal electrode is 50–200 nm.

3. The method for preparing an alkali-ion passivated lead-free perovskite light-emitting diode according to claim 1, characterized in that, Includes the following steps: After cleaning the ITO conductive glass, filter the hole injection layer solution, spin-coat it onto the clean ITO conductive glass surface, anneal it, and then cool it to room temperature. Then, prepare the hole transport layer solution, spin-coat the hole transport layer solution onto the surface of the hole injection layer obtained above, anneal and cool to room temperature; Subsequently, an alkali-passivated lead-free perovskite precursor solution was prepared. After filtering the alkali-passivated lead-free perovskite precursor solution through a polytetrafluoroethylene filter, it was spin-coated onto the surface of the hole transport layer. During the 30 to 60 seconds of spin-coating, an anti-solvent was rapidly added to the spin-coated surface. After annealing, the solution was cooled to room temperature. Next, an electron transport layer is deposited on the surface of the lead-free perovskite light-emitting layer obtained above, and an electrode modification layer is deposited on the surface of the electron transport layer. Finally, a metal electrode is deposited on the surface of the electrode modification layer to obtain a lead-free perovskite light-emitting diode based on an alkali ion passivation strategy.

4. The method for preparing an alkali-ion passivated lead-free perovskite light-emitting diode according to claim 3, characterized in that, The hole transport layer solution is composed of poly[N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine], poly(9-vinylcarbazole), poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-n-butyl)phenyl)-diphenylamine)], poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[ The mixture is prepared by dissolving any one of the following solids, namely [2,1,3]thiadiazole-4,8-diyl), poly(9,9-dioctylfluorene-2,7-diyl)-alt-(N,N'-diphenylbenzidine-N,N'-diyl), 4,4'-bis(9-carbazole)biphenyl, and 4,4',4”-tris(carbazole-9-yl)triphenylamine, in any one solvent, namely chlorobenzene, chloroform, and toluene, at a concentration of 1 to 50 mg / mL.

5. The method for preparing an alkali-ion passivated lead-free perovskite light-emitting diode according to claim 3, characterized in that, In the lead-free perovskite precursor solution, alkali ions , , The percentage of any one of the components in the total solid mass of the solution is 0% to 20%.

6. The method for fabricating an alkali-ion passivated lead-free perovskite light-emitting diode according to claim 3, characterized in that, The antisolvent is any one of toluene, chlorobenzene, methyl acetate, and ethyl acetate.

7. The method for preparing an alkali-ion passivated lead-free perovskite light-emitting diode according to claim 3, characterized in that, The electron transport layer material is any one of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, 4,6-bis(3,5-di(2-pyridinylphenyl)-2-methylpyrimidine, 4,6-bis(3,5-di(3-pyridinylphenyl)-2-methylpyrimidine, 1,3,5-tris[(3-pyridinyl)-3-phenyl]benzene, and 2,4,6-tris[3-(diphenylphosphoxy)phenyl]-1,3,5-triazole.

8. The method for preparing an alkali-ion passivated lead-free perovskite light-emitting diode according to claim 3, characterized in that, The electrode modification layer material is either lithium fluoride or 8-hydroxyquinoline-lithium, and the metal electrode material is either aluminum or silver.

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