CN110854276A

CN110854276A - Preparation method and application of titanium tetrafluoride passivated perovskite battery interface

Info

Publication number: CN110854276A
Application number: CN201911226162.6A
Authority: CN
Inventors: 杨化桂; 何敬敬; 侯宇; 杨双
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2019-12-04
Filing date: 2019-12-04
Publication date: 2020-02-28
Anticipated expiration: 2039-12-04
Also published as: CN110854276B

Abstract

The invention relates to a preparation method and application of a titanium tetrafluoride passivated perovskite battery interface. Dissolving 2-8 mg of titanium tetrafluoride powder in 1mL of N, N-dimethylformamide solution, diluting 2-20 mu L of titanium tetrafluoride-N, N-dimethylformamide solution, adding less than 20 mu L of solution into 100 mu L of FACS-based perovskite precursor solution with the concentration of 0.8-1.2 mol/mL, shaking up, spin-coating on titanium dioxide-covered conductive glass FTO to form a film, spin-coating a cavity layer after annealing and cooling, and evaporating conductive electrode silver to assemble a complete perovskite solar cell. According to the invention, fluorine and titanium ions of titanium tetrafluoride in the perovskite solution are spontaneously dispersed on the upper and lower interfaces of the perovskite absorption layer film, so that the corresponding defects at the interface of the battery film can be effectively passivated, the performance of the original battery is improved by about 12.6%, and the stability is obviously improved.

Description

Preparation method and application of titanium tetrafluoride passivated perovskite battery interface

Technical Field

The invention relates to a preparation method of an organic-inorganic mixed perovskite thin film, which has the defects of a passivation thin film and can improve the photoelectric conversion efficiency and the moisture stability. The method has important application in the fields of preparation and application of novel solar cells.

Background

Energy is the most important supporting point for the development of human society, along with the rapid development of society, the increasing exhaustion of non-renewable resources (petroleum, minerals, natural gas and the like) and the accompanying environmental problems (climate warming, haze and the like) force the human to look for new clean energy, and the effective utilization of clean energy such as solar energy, nuclear energy, wind energy, water energy and the like is more and more concerned in various countries in the world. As the most easily available renewable energy, solar energy is inexhaustible, safe and environment-friendly compared with other energy sources, and is the most important part of new energy. The solar cell directly converts light energy into electric energy through photoelectric or photochemical effects, and plays an important role in improving energy crisis and resource shortage. With the continuous and deep research in recent years, the development of solar cells has been greatly developed, and the solar cells are gradually one of the most popular fields in the 21 st century and the future world. Perovskite solar cells are an emerging solar cell technology that has emerged in recent years, but significant advances have been made in this short few years and energy conversion efficiencies have exceeded many other types of solar cells that have been developed over the years.

The perovskite type solar cell is generally in a sandwich structure, and particularly is a conductive glass/titanium dioxide dense thin film/perovskite/hole transport layer/back electrode, wherein an organic-inorganic hybrid perovskite thin film is a key component of the perovskite type solar cell and plays an important role in generation, separation and transmission of current carriers. At present, the laboratory certification efficiency of perovskite solar cells has broken through 25.2% and has reached the commercialization threshold, but its hysteresis and stability (especially in humid environments) are key issues limiting its further development. In response to these problems, component engineering, interface engineering, and additive engineering have been studied. Wherein the additives are engineered by adding the corresponding metal compounds, e.g. Na, as a monovalent metal⁺、K⁺And Rb⁺Divalent metal Ca²⁺,Sr²⁺,Cd²⁺And trivalent metal In³⁺,Sb³⁺Etc. can directly influence the crystallization behavior of the filmThe growth direction of the film is controlled, and the absorption band gap of the perovskite is adjusted, so that the internal defect density of the film is reduced, the hysteresis effect of the battery is reduced, the efficiency of the battery is obviously improved, and the stability of the perovskite battery is improved. Recently, the monovalent metal fluorides NaF and KF are discovered to form stronger ionic bonds with metal lead and organic cation formamidine or methylamine through fluorine ions, so that the perovskite thin film battery with high efficiency and high stability has better engineering for passivating interface defects. But fluoride-based polyvalent metal ions are less studied.

According to the invention, a proper amount of titanium tetrafluoride polyvalent metal fluoride is doped in the organic-inorganic hybrid perovskite precursor by using a simple spin coating process, and corresponding fluorine and titanium ions can be spontaneously dispersed at two ends of a film interface in the film forming process to modify the defects of the interface of the perovskite film. Meanwhile, the prepared film keeps excellent photoelectric correspondence, the photoelectric conversion efficiency can exceed 20%, and meanwhile, the outdoor humidity stability of the perovskite structure is greatly improved.

Disclosure of Invention

The invention aims to provide a preparation method and application for improving the photoelectric property and stability of a perovskite battery by spontaneously dispersing fluorine and titanium ions on a thin film interface through titanium tetrafluoride doped perovskite precursor solution, wherein the preparation method is simple and has high repeatability.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of titanium tetrafluoride passivated perovskite thin film interface comprises the following steps:

dissolving 2-8 mg of titanium tetrafluoride powder in 1mL of N, N-dimethylformamide solution, diluting 2-20 mu L of titanium tetrafluoride-N, N-dimethylformamide solution, adding less than 20 mu L of solution into 100 mu L of FACS-based perovskite precursor solution with the concentration of 0.8-1.2 mol/mL, shaking up, spin-coating on titanium dioxide-covered conductive glass FTO to form a film, annealing and cooling, spin-coating a cavity layer, evaporating and coating conductive electrode silver, and assembling into a complete perovskite solar cell.

Further, the titanium tetrafluoride powder is weighed and dissolved in a glove box under the protection of nitrogen atmosphere.

Further, the concentration of the titanium tetrafluoride-N, N-dimethylformamide mixed solution with the concentration of 2-8 mg/mL after being diluted by N, N-dimethylformamide is 0-1.2 mg/mL, and the preferred concentration is 0.4 mg/mL.

Furthermore, the FACs-based perovskite solution is prepared by dissolving 368.8-553.2 mg of lead iodide, 117.4-176.2 mg of lead bromide, 161.72-242.6 mg of formamidine iodide and 47.8-71.7 mg of cesium iodide in 1mL of a mixed solution of N, N-dimethylformamide and dimethyl sulfoxide (volume ratio is 4: 1). Then the solution is heated to 70-120 ℃ and stirred for 30-60 minutes.

Further, the titanium dioxide-covered conductive glass FTO is formed by spin-coating a corresponding isopropyl titanate ethanol solution on the conductive glass FTO, and calcining the conductive glass FTO for 30 to 60 minutes after the temperature is raised to 400 to 550 ℃ by a muffle furnace. .

Further, the titanium tetrafluoride solution with the concentration of less than 1.2mg/mL is added into the precursor solution, the perovskite thin film formed after spin coating is formed by heating at 100-120 ℃ for 5-10 minutes and heating at 80-120 ℃ for 10-60 minutes, and the thickness of the thin film is about 400 nm.

Furthermore, the titanium tetrafluoride has the characteristics of passivating the defects of the battery film, and improving the efficiency and stability of the perovskite battery.

Further, the application method comprises the following steps: after the perovskite solar cell is assembled by adopting a standard process, the photoelectric conversion efficiency is tested under the irradiation of a solar simulator.

The invention has the beneficial effects that:

(1) the simple titanium tetrafluoride solution is added into the precursor solution, fluorine and titanium ions can spontaneously migrate and disperse at two ends of the interface of the perovskite film, and the synthesized film is simple and convenient to operate and good in repeatability;

(2) the efficiency and the stability of the perovskite thin film are greatly improved after the titanium tetrafluoride is doped.

Drawings

FIG. 1 is a scanning electron micrograph of a perovskite thin film prepared in example 1;

FIG. 2 is a graph showing a current-voltage characteristic of the battery prepared in example 1;

fig. 3 is a graph of the complex impedance of the battery prepared in example 1;

FIG. 4 is an element distribution diagram of the perovskite thin film prepared in example 1 obtained by the time-of-flight secondary ion mass spectrometry technique.

Detailed Description

Example 1

Step one, preparation of titanium tetrafluoride doped perovskite film

484.1mg of lead iodide, 146.8mg of lead bromide, 202.2mg of formamidine iodide and 62.7mg of the iodide powder were first weighed out and dissolved in 1mL of a solvent of N, N-dimethylformamide and dimethyl sulfoxide (volume ratio: 4:1) to give a concentration of 1 mol/mL. Followed by heating at 120 ℃ with stirring for 1 hour to form a perovskite precursor solution. Adding 0-20 mu L of titanium tetrafluoride N, N-dimethylformamide solution with the concentration of 0.4mg/mL into 100 mu L of perovskite precursor solution, uniformly mixing, spin-coating on FTO glass covered by titanium dioxide, and then heating at 120 ℃ for 10 minutes and at 100 ℃ for 40 minutes.

Fig. 1 is a scanning electron microscope of the prepared thin film, and it can be seen that titanium tetrafluoride is doped to form a dense thin film.

Step two, performance characterization test

And adding 10 mu L of titanium tetrafluoride N, N-dimethylformamide solution with the concentration of 0.4mg/mL into 100 mu L of perovskite precursor solution, uniformly mixing, spin-coating on FTO glass covered by titanium dioxide, and then heating at 120 ℃ for 10 minutes and at 100 ℃ for 40 minutes. Cooling, spin-coating hole layer, evaporating silver electrode, assembling into perovskite solar cell, passing through solar simulator at 100mW cm^-2And testing the photoelectric conversion efficiency under the irradiation of standard light.

FIG. 2 shows that after the perovskite solar cell is assembled by adopting the standard process, the photoelectric conversion efficiency reaches 20.19 percent (short-circuit current is 22.95 mA/cm)²Open circuit voltage 1.17V, fill factor 75.20%).

Fig. 3 is a graph of composite impedance of a cell measured using standard techniques to assemble undoped titanium tetrafluoride and doped titanium tetrafluoride perovskite solar cells, with different bias voltages applied. The graph shows that the doping of corresponding titanium tetrafluoride in the perovskite can obviously improve the carrier recombination impedance.

Step three, element distribution of titanium fluoride doped perovskite film

484.1mg of lead iodide, 146.8mg of lead bromide, 202.2mg of formamidine iodide and 62.7mg of cesium iodide powder were weighed out and dissolved in 1mL of a solvent of N, N-dimethylformamide and dimethyl sulfoxide (volume ratio: 4:1) (concentration: 1 mol/mL). Followed by heating at 120 ℃ with stirring for 1 hour to form a perovskite precursor solution. And adding 10 mu L of titanium tetrafluoride N, N-dimethylformamide solution with the concentration of 0.4mg/mL into 100 mu L of perovskite precursor solution, uniformly mixing, spin-coating on the conductive glass ITO, and then heating at 120 ℃ for 10 minutes and at 100 ℃ for 40 minutes.

Fig. 4 is a time-of-flight secondary ion mass spectrometry technical characterization map of the prepared thin film, and it can be seen that most of fluorine ions are dispersed on the upper interface of the thin film, and most of titanium ions are dispersed on the lower interface of the thin film, and an ion distribution gradient is formed spontaneously.

Claims

1. A preparation method of a titanium tetrafluoride passivated perovskite battery interface is characterized by comprising the following steps:

dissolving 2-8 mg of titanium tetrafluoride powder in 1mL of N, N-dimethylformamide solution, diluting 2-20 mu L of titanium tetrafluoride-N, N-dimethylformamide solution, adding less than 20 mu L of solution into 100 mu L of FACS-based perovskite precursor solution with the concentration of 0.8-1.2 mol/mL, shaking up, spin-coating on titanium dioxide-covered conductive glass FTO to form a film, annealing and cooling, spin-coating a cavity layer, and evaporating conductive electrode silver to assemble the complete perovskite solar cell.

2. The method of claim 1, wherein the weighing and dissolving of the titanium tetrafluoride powder in N, N-dimethylformamide is performed in a glove box under a nitrogen atmosphere.

3. The method of claim 1, wherein the dilution of the solution of titanium tetrafluoride and N, N-dimethylformamide is N, N-dimethylformamide.

4. The method of making a titanium tetrafluoride passivated perovskite battery interface as claimed in claim 1 wherein the concentration of the diluent is less than 1.2 mg/mL.

5. The method of making a titanium tetrafluoride passivated perovskite battery interface as claimed in claim 4 wherein the concentration of the diluent is 0.4 mg/mL.

6. The method of claim 1, wherein 368.8-553.2 mg of lead iodide, 117.4-176.2 mg of lead bromide, 161.72-242.6 mg of formamidine iodide and 47.8-71.7 mg of cesium iodide are dissolved in 1mL of a mixed solution of N, N-dimethylformamide and dimethylsulfoxide; the volume ratio of the N, N-dimethylformamide to the dimethyl sulfoxide mixed solution is 4: 1; then the solution is heated to 70-120 ℃ and stirred for 20-60 minutes.

7. The method for preparing the titanium tetrafluoride passivated perovskite cell interface as claimed in claim 1, wherein the titanium dioxide covered conductive glass FTO is formed by spin coating a corresponding isopropyl titanate ethanol solution on the conductive glass FTO, and calcining the conductive glass FTO for 30-60 minutes at 400-550 ℃ through a muffle furnace.

8. The method for preparing the interface of the titanium tetrafluoride passivated perovskite battery according to claim 1, wherein the perovskite thin film formed after the spin coating is formed by heating at 100-120 ℃ for 5-10 minutes and heating at 80-120 ℃ for 10-60 minutes and annealing, and the thickness of the thin film is about 400 nm.

9. A perovskite cell made by the method of preparing a titanium tetrafluoride passivated perovskite cell interface as claimed in claim 1.

10. The method of making a titanium tetrafluoride passivated perovskite cell interface as claimed in claim 1 for use in perovskite solar cell applications.