Tailoring Multifunctional Amine Salts Based on Anisole Liquid Soaking for Fabricating Efficient and Stable Perovskite Solar Cells.

The post-treatment based on spin-coating (SC) organic amine salts is commonly used for surface modification of perovskite films to eliminate defects. However, there is still a lack of systematic study and a unified understanding of the functions and mechanisms of different organic amine salts. The SC method is also not conducive to the industrialization of solar cells. In this work, we study three different organic amine salts, and a passivation strategy for perovskite films based on green anisole liquid soaking (ALS) has been developed. Phenylethylammonium iodide (PEAI), diethylamine hydroiodide (DEAI), and guanidine hydroiodide (GAI) organic amine salt passivators are selected to modify perovskite films, and their effect and working mechanism are also systematically estimated. It is found that PEAI passivates shallow-level defects on the surface of perovskite films, while DEAI incorporates into the perovskite lattice to suppress point defects, and GAI eliminates excess PbI residuals in perovskite films. These three organic-amine-salt-modified devices achieve enhanced power conversion efficiencies (PCE) of 21.82% (PEAI-ALS), 21.74% (DEAI-ALS), and 22.21% (GAI-ALS), which is much higher than that of the pristine device without treatment (19.95%). The PCE of the PEAI-ALS device retains nearly 94% of the initial efficiency after 1200 h in unpackaged conditions and about 40% ambient humidity, achieving the best stability performance. Particularly, the PEAI-ALS device has the best comprehensive performance in efficiency and stability. And PEAI is estimated by the SC method and ALS method, and it is found that the PEAI-ALS device achieves a higher PCE compared to the PEAI-SC device (21.51%). We believe that the post-treatment based on a combination of appropriate amine salts and ALS enables a universal approach for fabrication of perovskite solar cells with enhanced photovoltaic performance.