Investigation On Crystal Growth And Humidity Stabilty Of The Active Layer In Perovskite Solar Cells

Perovskite solar cells have attracted extensive attention from researchers all over the world due to their low raw material prices,facile fabrication process and continuously increasing power conversion efficiency.However,the device stability of perovskite solar cells has seriously hindered its commercial development.There are many factors that affect the device stability,such as light,temperature and humidity,among which humidity is the most important.Because the original components of perovskite contain amine salts with hygroscopicity,which makes the perovskite film is easy to adsorb water to form specific hydrates in a humid environment,resulting in irreversible degradation of the film.Therefore,it is imperative to find effective strategies to avoid or mitigate moisture damage to the film.Herein,this paper focuses on the degradation mechanism of perovskite film under high humidity environment,and then improves the humidity stability of the film by improving the quality of perovskite film on this theoretical basis.The specific research contents are as follows:(1)The internal reasons of humidity-induced film degradation were deeply analyzed by tracking the degradation process of perovskite film in high humidity environment,and then comparative experiments were designed to further determine the degradation products.Finally,the degradation reaction equation of perovskite film is obtained.(2)The perovskite seed solution was constructed by adding organic powder methylamine bromide(MABr)to the lead iodide(PbI2)precursor solution in advance,and then the perovskite seed solution was used to grow perovskite film with larger grain size and less defect density.Finally,the optimized perovskite solar cells achieved 23.22%high performance and after 900 h long-term stability test,the cell performance did not degrade compared to the initial.(3)Thiamine hydrochloride(THM),a small molecular material,was introduced into the PbI2 precursor solution,and then the crystallization of the perovskite film was delayed through the bonding interaction between PbI2 and THM.Finally,a high-quality perovskite film with a smoother surface and better hydrophobicity was obtained and when the doping concentration of THM is 0.1 mg mL-1,the device obtains the best performance of 21.40%and the unpackaged device can retain 92%of its initial performance after being placed in a humidity environment of about 50%for 180 h.