Perovskite light-emitting diode based on ferrocene carboxylic acid modification and preparation method thereof

Abstract

The application relates to the technical field of perovskite materials, and discloses a perovskite light-emitting diode based on ferrocene formic acid modification and a preparation method thereof, the preparation method comprises the following steps: repeatedly cleaning an ITO substrate with deionized water, ethanol and dichloro, and then cleaning the substrate by using an ultraviolet ozone machine; depositing a PEDOT:PSS solution on the surface of the substrate obtained in step 1 in a rotary coating mode, and then performing annealing treatment; dissolving ferrocene formic acid into chlorobenzene, stirring the solution until the solution is dissolved to obtain a mixed solution, depositing the mixed solution on the surface of the substrate obtained in step 2 in a rotary coating mode, and then performing annealing treatment; and dissolving lead bromide, cesium bromide, phenethylammonium bromide and crown ether into a mixed solution of DMSO and PVP. The quasi-two-dimensional perovskite thin film prepared by the application has high light-emitting color purity and high quantum efficiency, and the prepared perovskite light-emitting device has high light-emitting performance and high stability.

Description

Technical Field

[0001] This invention relates to the field of perovskite materials technology, and in particular to perovskite light-emitting diodes based on ferrocene-modified acid and their preparation methods. Background Technology

[0002] Quasi-two-dimensional perovskite is considered a promising luminescent material for display applications due to its high color purity, wide color gamut, and spectral tunability. However, the photoelectric properties of current light-emitting diodes (LEDs) using perovskite materials as the emitting layer are still far inferior to those of state-of-the-art organic light-emitting diodes (OLEDs). This is due to two main factors: firstly, the uneven phase distribution within the formed film results in excessively low energy transfer efficiency; secondly, energy level mismatch and high defect density at the interface between the perovskite emitting layer and the hole transport layer not only reduce hole mobility but also lead to severe non-radiative recombination losses. These factors hinder further improvements in the overall performance of perovskite LEDs, thus severely restricting the industrial application of perovskite films and related devices.

[0003] Currently, the preparation process of perovskite thin films involves first dissolving long-chain organic groups, inorganic metal salts, and lead halide powder in a specific ratio into a highly polar solvent (typically DMSO or DMF) to form a perovskite precursor solution. Then, an appropriate amount of the precursor solution is dropped onto the substrate surface, followed by spin coating. During spin coating, a suitable amount of non-polar solvent is rapidly dropped onto the film surface at an appropriate time, facilitating rapid nucleation. The nucleation time in this process ranges from less than a second to several seconds. This rapid nucleation process leads to uneven nucleation on the film surface, making it more prone to uneven phase distribution within the quasi-two-dimensional film during subsequent heating growth. This results in low carrier energy transfer efficiency within the film, ultimately reducing the device's luminous efficiency. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a perovskite light-emitting diode based on ferrocene-modified perovskite and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The method for fabricating perovskite light-emitting diodes based on ferrocene-modified perovskite includes the following steps:

[0007] Step 1: Clean the ITO substrate repeatedly with deionized water, ethanol, and dichloroisocyanuric acid, and then clean it with a UV ozone generator.

[0008] Step 2: Deposit the PEDOT:PSS solution onto the substrate surface obtained in Step 1 by spin coating, and then perform annealing treatment;

[0009] Step 3: Dissolve ferrocene carboxylic acid into chlorobenzene and stir until the solution is dissolved to obtain a mixture, and deposit the mixture onto the surface of the substrate obtained in step 2 in a spin coating manner, and then perform annealing treatment;

[0010] Step 4: Dissolve lead bromide, cesium bromide, phenethylammonium bromide and crown ether into a mixed solution of DMSO and PVP, and stir until the solution is dissolved to obtain a perovskite precursor solution;

[0011] Step 5: The perovskite precursor solution obtained in step 4 is added dropwise to the surface of the substrate obtained in step 3, and then a perovskite thin film is prepared in a spin coating manner, and then drop ethyl acetate as an anti-solvent onto the surface of the perovskite thin film to rapidly crystallize the perovskite thin film, and then place the perovskite thin film on a heating table to perform annealing crystallization, and thus a quasi-two-dimensional perovskite thin film is obtained;

[0012] Step 6: Place the quasi-two-dimensional perovskite thin film obtained in step 5 into an evaporation instrument to evaporate an electron transport layer and a metal aluminum electrode, and thus a ferrocene carboxylic acid modified perovskite light-emitting diode is prepared.

[0013] Preferably, in step 1, the ultraviolet ozone machine is cleaned for 20 minutes.

[0014] Preferably, in step 2, the temperature of the annealing treatment is 150℃.

[0015] Preferably, in step 3, the weight ratio of ferrocene carboxylic acid to chlorobenzene is (0.001-0.005):1; and the temperature of the annealing treatment is 85℃.

[0016] Preferably, in step 4, the molar ratio of lead bromide, cesium bromide and phenethylammonium bromide is 1:(0.8-1.2):(0.35-0.45); the mass concentration of the crown ether is 4mg / mL; and the volume ratio of DMSO to PVP is 1:(0.08-0.15).

[0017] The preparation method of the ferrocene carboxylic acid modified perovskite light-emitting diode is used to prepare the ferrocene carboxylic acid modified perovskite light-emitting diode.

[0018] The present application has the following advantages:

[0019] The application spins the organic additive ferrocene carboxylic acid as a crosslinking agent on the hole transport layer before spinning the perovskite layer, which improves the phase distribution and tunes the perovskite energy level; first, the Lewis combination between the carboxyl group and lead bromide effectively delays its crystallization to adjust the phase distribution, and passivates the defects in the quasi-two-dimensional perovskite film, resulting in an increase in the large n-phase proportion with a narrow band gap; second, the interface dipole produced by the interaction between the functionalized ferrocene carboxylic acid and the perovskite surface leads to the transformation of perovskite energetics, thereby changing the energy level structure of the perovskite and affecting the carrier transport balance. This method not only has a simple preparation process, but also forms an efficient energy funnel structure, promotes the radiative recombination of photo-generated carriers, while reducing the potential barrier at the hole transport layer and perovskite interface, suppressing non-radiative recombination loss, thereby effectively improving the light-emitting efficiency of the quasi-two-dimensional perovskite film and the light-emitting performance of the prepared perovskite light-emitting device. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Current density-voltage characteristics of ITO / SnO2 / quasi-2D perovskite thin film / TPBi / LiF / Al and ITO / SnO2 / FcAd-modified quasi-2D perovskite thin film / TPBi / LiF / Al devices;

[0021] Figure 2 Absorption spectra and PL spectra on a logarithmic scale of quasi-2D perovskite (a) and FcAd-modified (b);

[0022] Figure 3 UPS spectra of quasi-2D perovskite and FcAd-modified perovskite thin films;

[0023] Figure 4 Bandgaps of quasi-2D perovskite and FcAd-modified perovskite obtained from absorption spectra;

[0024] Figure 5 Bandgap map of each functional layer in PeLEDs;

[0025] Figure 6 Current density-voltage-luminance curves of quasi-2D perovskite thin film PeLEDs based on no addition and addition of FcAd;

[0026] Figure 7 EQE current density curves of quasi-2D PeLEDs based on no addition and addition of FcAd. DETAILED DESCRIPTION

[0027] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application.

[0028] In one embodiment, the preparation method of the ferrocene carboxylic acid modified perovskite light emitting diode comprises the following steps:

[0029] Step 1: repeatedly clean the ITO substrate with deionized water, ethanol and dichloromethane, and then clean the ITO substrate with a UV ozone machine for 20 minutes;

[0030] Step 2: deposit the PEDOT:PSS solution on the surface of the substrate obtained in step 1 by spin coating, and then perform annealing treatment at a temperature of 150 DEG C;

[0031] Step 3: dissolve the ferrocene carboxylic acid in chlorobenzene and stir until the solution is dissolved to obtain a mixed solution, and then deposit the mixed solution on the surface of the substrate obtained in step 2 by spin coating, and then perform annealing treatment at a temperature of 85 DEG C;

[0032] Step 4: dissolve lead bromide, cesium bromide, phenethylammonium bromide and crown ether in a mixed solution of DMSO and PVP, and stir until the solution is dissolved to obtain a perovskite precursor solution;

[0033] Step 5: drop the perovskite precursor solution obtained in step 4 on the surface of the substrate obtained in step 3, and then prepare a perovskite thin film by spin coating, and then drop an anti-solvent ethyl acetate on the surface of the perovskite thin film to make the perovskite thin film crystallize rapidly, and then place the perovskite thin film on a heating table to perform annealing crystallization, thereby obtaining a quasi-two-dimensional perovskite thin film;

[0034] Step 6: place the quasi-two-dimensional perovskite thin film obtained in step 5 into an evaporation instrument to evaporate an electron transport layer and a metal aluminum electrode, thereby obtaining a ferrocene carboxylic acid modified perovskite light emitting diode.

[0035] As a preferred embodiment of the present application, in step 3, the weight ratio of ferrocene carboxylic acid to chlorobenzene is (0.001-0.005):1.

[0036] As a preferred embodiment of the present application, in step 4, the molar ratio of lead bromide, cesium bromide and phenethylammonium bromide is 1:(0.8-1.2):(0.35-0.45); the mass concentration of crown ether is 4 mg / mL; and the volume ratio of DMSO to PVP is 1:(0.08-0.15).

[0037] As a preferred embodiment of the present application, place the quasi-two-dimensional perovskite thin film obtained in step 5 into an evaporation instrument to evaporate an electron transport layer and a metal aluminum electrode.

[0038] The preparation method of the ferrocene carboxylic acid modified perovskite light-emitting diode is used to prepare the obtained ferrocene carboxylic acid modified perovskite light-emitting diode.

[0039] Example 1

[0040] An appropriate amount of dissolved perovskite precursor solution is added dropwise to the surface of the prepared PEDOT:PSS substrate, and then a thin film is prepared by using a spin coating method, then 150 microliters of ethyl acetate antisolvent is added dropwise to the surface of the perovskite thin film, and then the above perovskite thin film is placed on a heating table for later annealing crystallization to obtain a quasi-two-dimensional perovskite thin film.

[0041] Example 2

[0042] The same process as in Example 1 is used, except that a chlorobenzene solution of ferrocene carboxylic acid is spin-coated on the surface of the PEDOT:PSS substrate before spin-coating the perovskite precursor solution, and other conditions remain unchanged.

[0043] It can be seen that by adjusting the content of ferrocene carboxylic acid, an appropriate amount of ferrocene carboxylic acid can improve the electrical and optical properties of the quasi-two-dimensional perovskite thin film, which is beneficial to obtain a high-efficiency light-emitting device. Figures 1-7 It can be seen that the addition of ferrocene carboxylic acid can more effectively passivate the defect state density in the thin film, can obtain more effective energy transfer efficiency, and can have better energy level matching, thereby obtaining a high photoelectric conversion efficiency of more than 23%.

[0044] In the present application, before spin-coating the perovskite layer, the organic additive ferrocene carboxylic acid is spin-coated on the hole transport layer as a crosslinking agent, which improves the phase distribution and tunes the perovskite energy level; first, the Lewis combination between the carboxyl group and lead bromide effectively delays its crystallization to adjust the phase distribution, and passivates the defects in the quasi-two-dimensional perovskite film, resulting in an increase in the proportion of large n phase with a narrow band gap; second, the interface dipole produced by the interaction between the functionalized ferrocene carboxylic acid and the perovskite surface leads to a change in perovskite energetics, thereby changing the energy level structure of the perovskite and affecting the carrier transport balance. This method not only has a simple preparation process, but also forms a high-efficiency energy funnel structure, promotes the radiative recombination of photo-generated carriers, reduces the potential barrier at the interface between the hole transport layer and the perovskite, suppresses non-radiative recombination loss, and thus effectively improves the light-emitting efficiency of the quasi-two-dimensional perovskite thin film and the light-emitting performance of the prepared perovskite light-emitting device.

[0045] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for fabricating perovskite light-emitting diodes based on ferrocene-modified perovskite, characterized in that, Includes the following steps: Step 1: Clean the ITO substrate repeatedly with deionized water, ethanol, and dichloroisocyanuric acid, and then clean it with a UV ozone generator. Step 2: Deposit the PEDOT:PSS solution onto the substrate surface obtained in Step 1 by spin coating, and then perform annealing treatment; Step 3: Dissolve ferrocene in chlorobenzene and stir until the solution is dissolved to obtain a mixture. Deposit the mixture onto the substrate surface obtained in Step 2 by spin coating and then perform annealing treatment. Step 4: Dissolve lead bromide, cesium bromide, phenylethyl ammonium bromide and crown ether in a mixed solution of DMSO and PVP, and stir until the solution is dissolved to obtain a perovskite precursor solution; Step 5: The perovskite precursor solution obtained in Step 4 is dropped onto the substrate surface obtained in Step 3, and then a perovskite film is prepared by spin coating. Then, the antisolvent ethyl acetate is dropped onto the surface of the perovskite film to rapidly crystallize the perovskite film. Subsequently, the perovskite film is placed on a heating stage for annealing and crystallization to obtain a quasi-two-dimensional perovskite film. Step 6: Place the quasi-two-dimensional perovskite thin film obtained in Step 5 into a vapor deposition apparatus to vapor deposit an electron transport layer and a metallic aluminum electrode, thereby obtaining a perovskite light-emitting diode based on ferrocene-modified perovskite.

2. The method for preparing a perovskite light-emitting diode based on ferrocene-modified perovskite according to claim 1, characterized in that, In step 1, the UV ozone generator cleaning time is 20 minutes.

3. The method for preparing a perovskite light-emitting diode based on ferrocene-modified perovskite according to claim 1, characterized in that, In step 2, the annealing temperature is 150℃.

4. The method for preparing a perovskite light-emitting diode based on ferrocene-modified perovskite according to claim 1, characterized in that, In step 3, the weight ratio of ferroceneic acid to chlorobenzene is (0.001-0.005):1; The annealing temperature is 85℃.

5. The method for preparing a perovskite light-emitting diode based on ferrocene-modified perovskite according to claim 1, characterized in that, In step 4, the molar ratio of lead bromide, cesium bromide, and phenylethyl ammonium bromide is 1:(0.8-1.2):(0.35-0.45); The concentration of crown ether is 4 mg / mL; The volume ratio of DMSO to PVP is 1:(0.08-0.15).

6. The perovskite light-emitting diode based on ferrocene-modified perovskite obtained by the method for preparing perovskite light-emitting diode based on ferrocene-modified perovskite as described in any one of claims 1-5.

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