Multifunctional ionic liquid as solvent perovskite is no longer "afraid of moisture"

On March 28, a reporter from the Science and Technology Daily learned from Nanjing University of Technology that a team of academician Huang Wei of the Chinese Academy of Sciences and Professor Chen Yonghua from the Institute of Advanced Materials of Nanjing University of Technology has recently published in the top international journal "Science".
The research team pioneered the use of a multifunctional ionic liquid as a solvent to replace traditional organic solvents to prepare perovskite photovoltaic materials, which achieved the stability of the black phase formamidine lead iodide perovskite at room temperature and high humidity.
, Which solves the worldwide problem in the preparation process of traditional perovskite photovoltaic materials.
? Compared with traditional monocrystalline silicon cells, perovskite photovoltaic materials have become a research hotspot due to their advantages of lightness, thinness, low cost, environmental protection, and flexibility.
In traditional understanding, perovskite photovoltaic materials are afraid of water and air, especially perovskite photovoltaic materials represented by formamidine-based perovskite are very "sensitive" and need to be prepared under the protection of inert gas.
At the same time, only no more than 5 solvents can be applied to perovskite materials within the current scope of knowledge.
So many "pain points" make it difficult to expand the application.
"Why not boldly assume that perovskite can also be prepared in a high-humidity air environment?" Soon, Chen Yonghua's team focused their research on finding an environment-friendly, stable, and compatible solvent with physical and chemical properties.
In 2017, the team discovered a green proton-type ionic liquid, which was introduced into the preparation process due to the particularity of its functional group.
? "The unique anion and cation structure of ionic liquids can form a huge hydrogen bond network in the solution.
At the same time, organic anions and metal halides form chelates to adjust the properties of the precursor solution.
Its unique chemical action can effectively regulate calcium The crystallization kinetics of titanium ore leads to the growth of high-quality perovskite films.
” said the co-first author of the paper.
? Based on the characteristics of ionic liquids, the research team constructed a highly efficient and stable layered perovskite solar cell in 2020, with a photoelectric conversion efficiency of 18.
06%.
? Formamidine-based perovskite is considered to be the most promising material close to the theoretical limit efficiency due to its excellent properties.
However, its stability is poor and it is easily decomposed under high humidity conditions.
Starting from the structural design and preparation of the multifunctional ionic liquid solvent, the team found that the carbonyl group of the ionic liquid methylamine formate can chelate with the lead in lead iodide, and the amine group forms a hydrogen bond with iodine.
? Experimental results show that the device prepared by using ionic liquid methylamine formate as the perovskite precursor solvent finally achieved up to 24.
The photoelectric conversion efficiency is 1%, and the unencapsulated device maintains 80% and 90% of its initial efficiency for 500 hours under continuous heating and continuous light at 85 degrees Celsius.
? Green, non-toxic, stable and efficient, and low cost.
This achievement has created the preconditions for the large-scale production and utilization of perovskite solar cells.
Chen Yonghua said: "In the next 5 years, we will be committed to achieving the area of ​​perovskite solar cells from 0.
1 The square centimeter is enlarged to 100 square centimeters, realizing large-scale industrialized applications.
"