Study On The Application Of Solvent Extraction Engineering In CH₃NH₃PbI₃ Perovskite Solar Cells

Nowadays,people pay more and more attention to the renewable energy,especially the development of solar cells.The advent of perovskite solar cells,breaking the people’s awareness of traditional solar cells.In the past few years,the conversion efficiency rose from 3.8%to 22.1%,has achieved amazing success.However,in order to achieve commercialization of perovskite solar cells,it is necessary to overcome the stability problems,large-scale device preparation problems,material costs and environmental issues and so on.At present,the problems of poor stability and poor reproducibility exist in high efficiency perovskite solar cells.The main reason is in the process of preparation of perovskite layer,due to disorder of the grain growth will lead to grain size and defects,continuity and thickness of films were not controlled.Aiming at the above problems,the paper studies the preparation of perovskite solar cells by solvent extraction engineering in the air environment.Firstly,the anti-solvent of perovskite solar cells prepared by solvent extraction was screened and optimized.The anti-solvent acts as a rapid extraction solvent when the precursor solvent evaporates,allowing the solute to precipitate rapidly and in a direction,thereby weakening its sensitivity to the environment and increasing the repeatability of the process.In this paper,the perovskite solar cells were prepared by one-step solution,and different anti-solvents(toluene,chlorobenzene,ethyl acetate,acetonitrile,acetone,isopropyl alcohol,ethanol,ultra pure water)were selected for the solvent extraction.The experimental results showed that,the perovskite film obtained by ethyl acetate extraction has the best absorption in the whole absorption spectrum and the strongest crystal diffraction peak,the film is compact and smooth,high coverage rate,the device filling factor is more than 70%,the open circuit voltage exceeds IV,and the photoelectric conversion efficiency is up to 12.79%,the devices prepared by other selected anti-solvent are far inferior than it.Secondly,the effects of solvent extraction time on the performance of perovskite solar cells were investigated.In the experiment,ethyl acetate was used as the anti-solvent.After spin coating of perovskite precursor solution,solvent extraction was carried out by adding the same amount of ethyl acetate in the third second,6th second,9th second,12th second and 15th second to promote the rapid precipitation of perovskite to form a thin film.It was found that the perovskite thin films prepared by adding the anti-solvent ethyl acetate in the 9th second has high spectral absorption,the crystal crystallinity is the strongest,the grain size distribution is small,the grain boundary is obvious,the film is dense,the film coverage rate is high,and the efficiency of the device can reach up to 14.78%.The devices prepared by the anti-solvent at other droping times are less than this.