CN113506858A - Cadmium-doped perovskite light emitting diode and preparation method thereof - Google Patents
Cadmium-doped perovskite light emitting diode and preparation method thereof Download PDFInfo
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Abstract
The application discloses a cadmium-doped perovskite light emitting diode and a preparation method thereof, relating to the technical field of photoelectric device preparation and comprising the following steps: spin-coating an electron injection layer precursor solution on the cleaned conductive substrate to form an electron injection layer; dissolving lead halide, halide salt, an organic passivator and cadmium salt in an organic solvent to obtain a cadmium-doped perovskite precursor solution; spin-coating the perovskite precursor solution on the electron injection layer, dripping chlorobenzene antisolvent in the spin-coating process, and annealing to form a perovskite light emitting layer; and (3) spin-coating the hole injection layer precursor solution on the perovskite light emitting layer to form a hole injection layer, and then sequentially carrying out vacuum thermal evaporation on the hole injection layer to form a metal electrode modification layer and a metal electrode to obtain the cadmium-doped perovskite light emitting diode. According to the method, the crystal grain size is effectively reduced by doping cadmium, the phenomenon of phase separation of mixed halogen is inhibited, and the fluorescence quenching on the surface of the perovskite light emitting layer is inhibited, so that the cadmium-doped perovskite light emitting diode has better spectral stability.
Description
Technical Field
The application relates to the technical field of photoelectric device preparation, in particular to a cadmium-doped perovskite light-emitting diode and a preparation method thereof.
Background
Currently, perovskite materials, one of the most competitive materials in the photovoltaic field in recent years, mainly benefit from their excellent photophysical properties, such as direct band gap, long carrier lifetime, long diffusion length, high absorption coefficient, and the like. In addition, the perovskite material can be prepared by a solution method, the preparation process is simple, and the perovskite material can be used as a light absorption material to be applied to a solar cell and can also show great application potential in the fields of laser, photoelectric detection and luminescence due to the excellent characteristics. The perovskite may be applied to a light emitting device in the form of quantum dots. However, the synthesis process of the quantum dot is too complicated, ligand assistance is required for the self stability of the quantum dot, and the ligand insulation causes that the quantum dot is not suitable for an electroluminescent device.
In the related art, the perovskite material is mostly applied to a polycrystalline thin film prepared by a solution method. Based on the characteristic that the band gap of the perovskite material is adjustable, the light-emitting wavelength can cover the near ultraviolet-visible light-infrared band, so that the perovskite material has important research significance and application potential in light-emitting display.
The perovskite material with variable halogen is used for preparing electroluminescent devices with different luminous peaks, the luminous peak can be adjusted from 470nm to 800nm, but the stability of the obtained light-emitting diode needs to be improved. In addition, if electroluminescence covering the entire visible spectrum is to be realized, continuous spectral adjustment must be realized, and the emission peak of perovskite can be continuously adjusted only by mixing halogen. However, red-light mixed-halogen perovskites can suffer from problems with mixed-halogen phase separation under bias, such as the creation of bromine-rich and iodine-rich domains, which can cause macroscopic spectral changes, resulting in spectral instability.
Disclosure of Invention
In view of one of the defects in the prior art, the present application aims to provide a cadmium-doped perovskite light emitting diode and a manufacturing method thereof, so as to solve the problems of insufficient stability and unstable spectrum of the light emitting diode in the related art.
In a first aspect, the present application provides a method for preparing a cadmium-doped perovskite light emitting diode, comprising the steps of:
spin-coating an electron injection layer precursor solution on the cleaned conductive substrate to form an electron injection layer;
dissolving lead halide, halide salt, an organic passivator and cadmium salt in an organic solvent to obtain a cadmium-doped perovskite precursor solution;
spin-coating the perovskite precursor solution on the electron injection layer, dripping a chlorobenzene antisolvent in the spin-coating process, and annealing to form a perovskite light emitting layer;
and (3) spin-coating a hole injection layer precursor solution on the perovskite light emitting layer to form a hole injection layer, and then sequentially carrying out vacuum thermal evaporation on the hole injection layer to form a metal electrode modification layer and a metal electrode, thereby obtaining the cadmium-doped perovskite light emitting diode.
In some embodiments, spin-coating an electron injection layer precursor solution on a cleaned conductive substrate to form an electron injection layer includes:
when the electron injection layer precursor solution is a zinc oxide quantum dot solution, spin-coating the zinc oxide quantum dot solution on the conductive substrate to form an electron injection layer;
when the electron injection layer precursor solution is a tin oxide quantum dot solution, the tin oxide quantum dot solution is spin-coated on the conductive substrate, and then the electron injection layer is formed by annealing at 180 ℃ for 30 min.
In some embodiments, after forming the electron injection layer, the method further includes:
and (3) spinning and coating a PEIE solution on the electron injection layer, and annealing at 90 ℃ for 10min to form a PEIE modification layer.
In some embodiments, the molar ratio of the lead halide, the halogen salt and the organic passivating agent is 1: 1.2-2.4: 0.5-0.7.
In some embodiments, the lead halide comprises PbBr2Or PbI2At least one of;
the halide salt comprises at least one of CsBr, FAI and MAI;
the organic passivator is penta-aminovaleric acid 5-AVA or iodized penta-aminovaleric acid 5-AVAI.
In some embodiments, the cadmium salt is any one of cadmium iodide, cadmium bromide, cadmium chloride, and cadmium acetate dihydrate.
In some embodiments, the hole injection layer precursor solution is a TFB solution of 13mg/ml, and the solvent is chlorobenzene.
In some embodiments, the cleaning of the conductive substrate specifically includes:
sequentially adopting deionized water, acetone, isopropanol and absolute ethyl alcohol to carry out ultrasonic cleaning on the conductive substrate;
drying the cleaned conductive substrate by using nitrogen, and performing UV-zone treatment to obtain a cleaned conductive substrate;
the conductive substrate is an Indium Tin Oxide (ITO) substrate with an etching shape.
In some embodiments, when annealing to form the perovskite light emitting layer, the perovskite precursor solution is spin coated and then annealed at 100 ℃ for 10min to form the perovskite light emitting layer with a stable perovskite phase.
A second aspect of the present application provides a cadmium-doped perovskite light emitting diode: the cadmium-doped perovskite light-emitting diode is prepared by the preparation method.
The beneficial effect that technical scheme that this application provided brought includes:
the cadmium-doped perovskite light-emitting diode and the preparation method thereof comprise the steps of spin-coating an electron injection layer precursor solution on a cleaned conductive substrate to form an electron injection layer, dissolving lead halide, halogen salt, an organic passivator and cadmium salt in an organic solvent to obtain the cadmium-doped perovskite precursor solution, spin-coating the perovskite precursor solution on the surface of the electron injection layer, dropwise adding a chlorobenzene antisolvent in the spin-coating process, annealing to form a perovskite light-emitting layer, spin-coating a hole injection layer precursor solution on the perovskite light-emitting layer, forming the hole injection layer, and then sequentially carrying out vacuum thermal evaporation on the hole injection layer to form a metal electrode modification layer and a metal electrode to obtain the cadmium-doped perovskite light-emitting diode. Cadmium does not enter the interior of the perovskite crystal, and is only passivated at the interface of the perovskite polycrystal, and the cadmium can influence the perovskite crystallization rate, reduce the grain size, inhibit the growth of grains and simultaneously distribute in the grain gaps to inhibit the migration of halogen ions, thereby inhibiting phase separation; in addition, cadmium in the perovskite precursor liquid fills up metal vacancy defects on the electron injection layer through annealing, and surface defects of the cadmium are passivated to effectively inhibit the reaction of the electron injection layer and the perovskite interface under the long-term working condition, so that the stability of the device is improved. Therefore, the doping of cadmium is utilized to effectively reduce the grain size and simultaneously inhibit the phase separation phenomenon of the mixed halogen, and the fluorescence quenching effect on the surface of the perovskite light emitting layer is also effectively inhibited; the obtained cadmium-doped perovskite light-emitting diode has better spectral stability and good device stability.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method of making a cadmium-doped perovskite light emitting diode according to an embodiment of the present disclosure;
FIG. 2 is a schematic structural diagram of a cadmium-doped perovskite light emitting diode according to an embodiment of the present disclosure;
FIG. 3 is a morphology chart of perovskite thin films prepared in example 1 and comparative example 1 of the present application;
FIG. 4 is a graph of the photoelectric properties of a cadmium-doped perovskite light emitting diode prepared in example 1 of the present application;
FIG. 5 is a spectrum of a cadmium-doped LED prepared in example 1 of the present application at different voltages;
FIG. 6 is a graph showing the photoelectric characteristics of a perovskite light emitting diode without cadmium doping prepared in comparative example 1 of the present application;
FIG. 7 is a graph of normalized spectra at different voltages for cadmium-free perovskite light emitting diodes prepared in comparative example 1 of the present application;
FIG. 8 is a time-resolved transient fluorescence spectrum of perovskite light emitting layers prepared in example 1 of the present application and comparative example 1;
fig. 9 is a graph showing the photoelectric characteristics of a cadmium bromide-doped near-infrared light-emitting device prepared in example 2 of the present application;
fig. 10 is a life test chart of the cadmium chloride-doped perovskite near-infrared light-emitting device prepared in example 3 of the present application;
fig. 11 is a graph showing the photoelectric characteristics of the cadmium acetate dihydrate doped perovskite near-infrared light-emitting device prepared in example 4 of the present application;
FIG. 12 is a MAPbI doped cadmium acetate dihydrate prepared in example 5 of the present application3Perovskite fluorescence quantum efficiency (PLQY) test plots.
Reference numerals:
1. a conductive substrate; 2. an electron injection layer; 3. a perovskite light emitting layer; 4. a hole injection layer; 5. metal electrode modification layer and metal electrode.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
As shown in fig. 1, an embodiment of the present application provides a method for manufacturing a cadmium-doped perovskite light emitting diode, which includes the steps of:
s1, spin-coating an electron injection layer precursor solution on the cleaned conductive substrate to form an electron injection layer.
S2, dissolving lead halide, halide salt, an organic passivator and cadmium salt in an organic solvent until the lead halide, the halide salt, the organic passivator and the cadmium salt are completely dissolved to obtain the cadmium-doped perovskite precursor liquid.
In this embodiment, the organic solvent may be at least one of dimethylformamide DMF and dimethylsulfoxide DMSO. Preferably, the solution after complete dissolution can be filtered by a 0.22 micron filter head to obtain the perovskite precursor solution, and then the filtered perovskite precursor solution can be spin-coated on the prepared electron injection layer by using a spin coater.
S3, spin-coating the perovskite precursor solution on the electron injection layer, dropwise adding a chlorobenzene antisolvent in the spin-coating process, and annealing to form a perovskite light emitting layer, namely the perovskite thin film. The perovskite light emitting layer is composed of a plurality of nano particles, a large number of pores exist, and the structure can improve the light coupling-out rate.
And S4, spin-coating a hole injection layer precursor solution on the perovskite light emitting layer to form a hole injection layer, and then sequentially carrying out vacuum thermal evaporation on the hole injection layer to form a metal electrode modification layer and a metal electrode to obtain the cadmium-doped perovskite light emitting diode.
Optionally, the metal electrode modification layer is MoOxThe metal electrode is Au.
In this embodiment, the conductive substrate may be a glass conductive substrate or an indium tin oxide substrate.
Preferably, the cleaning of the conductive substrate specifically includes the following steps:
firstly, deionized water, acetone, isopropanol and absolute ethyl alcohol are sequentially adopted to carry out ultrasonic cleaning on the conductive substrate. Optionally, the time duration of each ultrasonic cleaning is 15 min.
And then, drying the cleaned conductive substrate by using nitrogen, and carrying out ultraviolet ozone UV-zone treatment to obtain the cleaned conductive substrate. Wherein, an ultraviolet ozone cleaning machine with power of 40W is selected for carrying out UV-zone treatment for 15 min.
Preferably, the conductive substrate is an Indium Tin Oxide (ITO) substrate with an etching shape.
In addition to the above embodiments, in the present example, the electron injection layer precursor solution is a zinc oxide quantum dot solution or a tin oxide quantum dot solution.
When the electron injection layer precursor solution is a zinc oxide quantum dot solution, the zinc oxide quantum dot solution is spin-coated on the conductive substrate to form an underlying electron injection layer.
When the electron injection layer precursor solution is a tin oxide quantum dot solution, the tin oxide quantum dot solution is spin-coated on the conductive substrate, and then the substrate is annealed at 180 ℃ for 30min to form the bottom electron injection layer.
Preferably, the thickness of the resulting electron injection layer is 30 nm.
Further, after the electron injection layer is formed, the method further comprises the following steps:
and (3) spinning and coating a PEIE solution on the electron injection layer, and annealing for 10min at 90 ℃ to form a PEIE modification layer. Optionally, the thickness of the PEIE modification layer is 0.1-0.3nm, and in this embodiment, the thickness of the PEIE modification layer is 0.2 nm.
In this embodiment, the molar ratio of the lead halide, the halide salt and the organic passivation agent is 1: 1.2-2.4: 0.5-0.7.
Alternatively, the lead halide comprises PbBr2Or PbI2At least one of (1).
The halide salt comprises at least one of cesium bromide CsBr, iodoformamidine FAI and iodomethylamine MAI.
The organic passivator is penta-aminovaleric acid 5-AVA or iodized penta-aminovaleric acid 5-AVAI.
Further, the cadmium salt is any one of cadmium iodide, cadmium bromide, cadmium chloride and cadmium acetate dihydrate. In the embodiment, the obtained perovskite light emitting layer is preferably a cadmium-doped bromine-iodine blended perovskite with fine and uniform crystal grains.
Further, when the perovskite light emitting layer is formed by spin coating and annealing the precursor solution, annealing at 100 ℃ for 10min is preferable to form the perovskite light emitting layer of the stable perovskite phase.
Alternatively, the hole injection layer precursor solution may be a TFB (1,2,4, 5-tetrakis (trifluoromethyl) benzene) solution.
In this example, TFB solid was dissolved in chlorobenzene at a concentration of 13mg/ml, and stirred at room temperature to obtain a hole injection layer precursor solution. The thickness of the prepared hole injection layer is 30-40 nm.
The embodiment of the application also provides a cadmium-doped perovskite light-emitting diode which is prepared by the preparation method.
In order that the present application may be more readily understood, specific embodiments thereof will be described further below.
Example 1
first, take 1.5X 1.5cm2The glass conductive substrate is subjected to ultrasonic cleaning in an ultrasonic cleaning instrument by sequentially adopting deionized water, acetone, isopropanol and absolute ethyl alcohol, and the ultrasonic cleaning time is 15min each time.
Then, the glass substrate was dried with nitrogen gas and subjected to UV-zone treatment in an ultraviolet cleaning ozone machine with a power of 40W for 15min to obtain a clean glass conductive substrate.
mixing FAI, CsBr and PbI according to the mol ratio of 1.9:0.5:0.8:0.2:0.52、PbBr25-AVAI was dissolved in 1ml of DMF solvent, while adding 2.7mg by mass of CdI2The above weighing error is controlled within 0.1 mg. And after complete dissolution, filtering by using a 0.22 micron filter head to obtain the perovskite precursor liquid.
Step 3, device preparation:
firstly, a zinc oxide quantum dot solution is spin-coated on a cleaned clean glass conductive substrate to form an electron injection layer with a thickness of 30nm without annealing, secondly, a PEIE solution is spin-coated on the electron injection layer with a thickness of 2nm, and a PEIE modification layer is formed by annealing at 100 ℃ for 10 min.
And then, transferring the glass conductive substrate with the electron injection layer and the PEIE modification layer to a glove box to spin-coat the perovskite precursor liquid, dripping chlorobenzene antisolvent in the spin-coating process, and annealing at 100 ℃ for 10min to form the perovskite light emitting layer.
Finally, a TFB solution is spin-coated on the perovskite light emitting layer to be 40nm thick, a hole injection layer can be formed without annealing, and then the hole injection layer is transferred into a vacuum cavity, and the vacuum degree is kept to be 4 multiplied by 10-4Pa, carrying out vacuum thermal evaporation to form a metal electrode modification layer and a metal electrode to obtain the cadmium-doped iodine-bromine blending system perovskite hairA photodiode.
As comparative example 1, a cadmium-free doped perovskite light emitting diode was prepared, i.e. comparative example 1 differs from the above-described example 1 in that: when the perovskite precursor solution is prepared in the step 2, 2.7mg of CdI is not added2。
As can be seen from FIG. 3, the doping or non-doping of cadmium directly affects the morphology of perovskite, and essentially affects the crystallization rate of perovskite. Cadmium doping causes a large amount of nucleation and regrowth within a short time, resulting in a reduction in the grain size.
Fig. 4 and 5 show the photoelectric characteristics of the cadmium-doped perovskite light emitting diode of example 1, which has an external quantum efficiency of 15.01% and a very stable spectrum without any shift at different biases.
Fig. 6 and 7 are photoelectric characteristics of the cadmium-free doped perovskite mixed halogen light emitting diode prepared in comparative example 1, which has an external quantum efficiency of only 11.5%, and fig. 6 shows that the normalized spectrum of the device is shifted by about 10nm at different biases, and the spectrum shows unstable characteristics at different biases.
Fig. 8 shows the carrier lifetime of the cadmium doped perovskite light emissive layer with or without cadmium, and it can be seen from the figure that the cadmium doped perovskite prepared in example 1 has a higher lifetime. Fitting finds that the carrier lifetime is improved from 151ns to 362ns after cadmium doping, which indicates that the crystal quality is higher after cadmium doping.
In contrast, cadmium-doped perovskite affects the crystallization rate, so that the grain size is reduced, the perovskite crystal defects are passivated, the device efficiency is improved, the EQE (external quantum efficiency) reaches 15.01%, the average external quantum efficiency is improved by one third compared with that of an undoped cadmium light-emitting diode (external quantum efficiency is 11.5%), and most importantly, the spectrum of the mixed halogen perovskite electroluminescent device is more stable under different bias voltages.
Example 2
This example 2 differs from the above example 1 in that: when the perovskite precursor liquid is prepared in the step 2, FAI and Pb are mixed according to the molar ratio of 2:1:0.7I25-AVA was dissolved in 1ml of DMF solvent, and CdBr was added thereto in an amount of 1.36mg2The above weighing error is controlled within 0.1 mg. I.e. CdBr2And adding a pure iodine system to finally obtain the cadmium-doped near-infrared perovskite light-emitting diode.
As comparative example 2, a cadmium-free doped pure iodine system perovskite light emitting diode was prepared, i.e., comparative example 2 differs from example 2 above in that: when the perovskite precursor solution is prepared in the step 2, 1.36mg of CdBr is not added2。
As can be seen from fig. 9, when cadmium bromide is added to the pure iodine perovskite, compared with a pure iodine perovskite light emitting diode (efficiency is 14.4%) without cadmium bromide, the efficiency is improved by 15.14%, the average external quantum efficiency is improved by 5%, which indicates that cadmium is doped in the pure iodine perovskite, and the improvement effect is also achieved.
Example 3
This example 3 differs from the above example 2 in that: when preparing the perovskite precursor liquid in the step 2: the cadmium salt is cadmium chloride, and the added mass is 0.98 mg. Namely CdCl2And adding a pure iodine system to finally obtain the cadmium-doped pure iodine system perovskite light-emitting diode.
By adding cadmium chloride into the pure iodine system perovskite light-emitting diode, the luminous external quantum efficiency of the prepared device is not obviously improved, but the doped device shows good device stability. For the device at 10mA/cm2The attenuation test is carried out under the constant current density, and the result is shown in fig. 10, and it can be seen that the external quantum efficiency of the device is rapidly improved from 1.8 to about 13 within the initial 20s time, and then is maintained at about 13% all the time within the 1000s time range, thus showing good device stability.
Example 4
This example 4 differs from the above example 2 in that: when preparing the perovskite precursor liquid in the step 2: the added cadmium salt is cadmium acetate dihydrate, and the added mass is 0.6 mg. Namely, cadmium acetate dihydrate is added into a pure iodine system, and finally the cadmium-doped pure iodine system perovskite light-emitting diode is obtained.
As shown in fig. 11, the device prepared by adding cadmium acetate dihydrate to the pure iodine perovskite light-emitting device has an external light-emitting quantum efficiency of 14.8%. The external quantum efficiency of the device was also somewhat improved compared to comparative example 2.
It can be seen that different cadmium salts can adapt to iodine-containing perovskites and achieve external quantum efficiencies of over 14%, indicating that coupling effects exist between cadmium and iodine to promote device efficiency.
Example 5
This example provides a cadmium doped MAPbI3Perovskite light emitting diode and preparation method thereof.
first, take 1.5X 1.5cm2The glass conductive substrate is subjected to ultrasonic cleaning in an ultrasonic cleaning instrument by sequentially adopting deionized water, acetone, isopropanol and absolute ethyl alcohol, and the ultrasonic cleaning time is 15min each time.
Then, the glass substrate was dried with nitrogen gas and subjected to UV-zone treatment in an ultraviolet cleaning ozone machine with a power of 40W for 15min to obtain a clean glass conductive substrate.
adding MAI and PbI according to the mol ratio of 1.2:1:0.725-AVA was dissolved in a mixed solvent of 1ml of DMF and 10. mu.l of DMSO, and 0.8mg by mass of cadmium acetate dihydrate was added thereto, with the above weighing error being controlled to be within 0.1 mg. And after complete dissolution, filtering by using a 0.22 micron filter head to obtain the perovskite precursor liquid.
Step 3, device preparation:
firstly, a tin dioxide quantum dot solution is coated on a cleaned clean glass conductive substrate in a spin coating mode with the thickness of 30nm, an electron injection layer is formed by annealing at 180 ℃ for 30min, secondly, a PEIE solution is coated on the electron injection layer in a spin coating mode with the thickness of 2nm, and a PEIE modification layer is formed by annealing at 100 ℃ for 10 min.
And then, transferring the glass conductive substrate with the electron injection layer and the PEIE modification layer to a glove box to spin-coat the perovskite precursor liquid, dripping chlorobenzene antisolvent in the spin-coating process, and annealing at 100 ℃ for 10min to form a perovskite light emitting layer, namely the perovskite thin film.
Finally, a TFB solution is spin-coated on the perovskite light emitting layer to be 40nm thick, a hole injection layer can be formed without annealing, and then the hole injection layer is transferred into a vacuum cavity, and the vacuum degree is kept to be 4 multiplied by 10-4And Pa, performing vacuum thermal evaporation to form a metal electrode modification layer and a metal electrode to obtain the cadmium-doped perovskite light-emitting diode.
To prepare cadmium-free doped MAPbI3A perovskite light emitting diode was used as comparative example 3, i.e. comparative example 3 differs from example 5 described above in that: and (3) when the perovskite precursor solution is prepared in the step 2, 0.8mg of cadmium acetate dihydrate is not added.
The perovskite thin films obtained by spin coating in the example 5 and the comparative example 3 are subjected to a fluorescence quantum efficiency PLQY test, and the test result is shown in fig. 11, compared with the perovskite thin film which is not doped with cadmium acetate dihydrate, the perovskite luminescence peak of the perovskite thin film after cadmium doping is obviously enhanced, and the PLQY is improved from 0.37% to 3.2% and is improved by 8.6 times. In addition, external quantum efficiency tests are carried out on the perovskite light emitting diode which is not doped with cadmium acetate dihydrate and the perovskite light emitting diode which is doped with the cadmium acetate dihydrate, and the results show that after the cadmium is doped, the EQE is improved to 0.88 percent from 0.05 percent and is improved by 17 times.
According to the embodiment of the application, cadmium doping is utilized to effectively increase the nucleation rate of the crystal, reduce the grain size of the perovskite, passivate the crystal defects on the surface of the perovskite, improve the radiative recombination of the perovskite crystal, and doping causes the change of the morphology structure of the perovskite light emitting layer, the smaller grain size and the cadmium outside the crystal can effectively fix perovskite halogen in the crystal, and limit excitons formed under the action of an electric field in the crystal, and the exciton recombination is promoted in a space limiting manner, so that the exciton recombination rate is improved; in addition, for the mixed halogen, the excessive cadmium is distributed in the grain gaps, the separation of the mixed halogen can be inhibited, the perovskite phase is stabilized, the dissociated halogen fills the halogen vacancy defects of the perovskite, and the stability of the perovskite is further improved.
According to the preparation method of the cadmium-doped perovskite light-emitting diode, low-temperature preparation is adopted in the whole process, no additional organic passivator is added, the process is simple, the requirement on the equipment threshold is low, the production cost is greatly reduced, and the preparation method is suitable for industrial production; the cadmium-doped perovskite light-emitting diode prepared by the method has high external quantum efficiency, and the prepared cadmium-doped iodine-bromine blended perovskite light-emitting device has strong spectral stability under different current densities. The spectrum does not move in the working voltage range, the phenomenon of phase separation does not occur, and the method has important reference significance for display application and research of later-stage perovskite fluorescence, white light emission and the like.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.
Claims (10)
1. A preparation method of a cadmium-doped perovskite light emitting diode is characterized by comprising the following steps:
spin-coating an electron injection layer precursor solution on the cleaned conductive substrate to form an electron injection layer;
dissolving lead halide, halide salt, an organic passivator and cadmium salt in an organic solvent to obtain a cadmium-doped perovskite precursor solution;
spin-coating the perovskite precursor solution on the electron injection layer, dripping a chlorobenzene antisolvent in the spin-coating process, and annealing to form a perovskite light emitting layer;
and (3) spin-coating a hole injection layer precursor solution on the perovskite light emitting layer to form a hole injection layer, and then sequentially carrying out vacuum thermal evaporation on the hole injection layer to form a metal electrode modification layer and a metal electrode to obtain the cadmium-doped perovskite light emitting diode.
2. The method of manufacturing a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein an electron injection layer precursor solution is spin-coated on the cleaned conductive substrate to form an electron injection layer, specifically comprising:
when the electron injection layer precursor solution is a zinc oxide quantum dot solution, spin-coating the zinc oxide quantum dot solution on the conductive substrate to form an electron injection layer;
and when the precursor solution of the electron injection layer is a tin oxide quantum dot solution, spin-coating the tin oxide quantum dot solution on the conductive substrate, and annealing at 180 ℃ for 30min to form the electron injection layer.
3. The method of making a cadmium-doped perovskite light emitting diode as claimed in claim 1, further comprising, after forming the electron injection layer:
and (3) spinning and coating a PEIE solution of polyethenoxy ethylene imine on the electron injection layer, and annealing at 90 ℃ for 10min to form a PEIE modification layer.
4. The method of making a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein:
the molar ratio of the lead halide to the halide salt to the organic passivator is 1: 1.2-2.4: 0.5-0.7.
5. The method of making a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein:
the lead halide comprises PbBr2Or PbI2At least one of;
the halide salt comprises at least one of CsBr, FAI and MAI;
the organic passivator is penta-aminovaleric acid 5-AVA or iodized penta-aminovaleric acid 5-AVAI.
6. The method of making a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein:
the cadmium salt is any one of cadmium iodide, cadmium bromide, cadmium chloride and cadmium acetate dihydrate.
7. The method of making a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein: the hole injection layer precursor solution is a TFB solution with the concentration of 13mg/ml, and the solvent is chlorobenzene.
8. The method of manufacturing a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein cleaning the conductive substrate specifically comprises:
sequentially adopting deionized water, acetone, isopropanol and absolute ethyl alcohol to carry out ultrasonic cleaning on the conductive substrate;
drying the cleaned conductive substrate by using nitrogen, and performing UV-zone treatment to obtain a cleaned conductive substrate;
the conductive substrate is an Indium Tin Oxide (ITO) substrate with an etching shape.
9. The method of making a cadmium-doped perovskite light emitting diode as claimed in claim 1, wherein: when the perovskite light emitting layer is formed by annealing, the perovskite precursor solution is annealed for 10min at 100 ℃ after being spin-coated, and the perovskite light emitting layer with stable perovskite phase is formed.
10. A cadmium-doped perovskite light emitting diode, characterized in that: the cadmium-doped perovskite light-emitting diode is prepared by the preparation method of any one of claims 1 to 9.
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