Antisolvent engineering on low-temperature processed CsPbI inorganic perovskites for improved performances of solar cells.

CsPbI inorganic perovskites with ideal bandgap and much enhanced thermal stability compared with organic-inorganic hybrid perovskites, have attracted much interest in the field of solar cells. The performances of solar cells highly depend on the quality of perovskite films, yet the research on fabrication methods of inorganic perovskites is far below that of organic-inorganic hybrid counterparts. Antisolvent engineering is a widely used method in controlling the morphology and crystallinity of organic-inorganic hybrid perovskites. Its effect varies with parameters such as the physicochemical properties of antisolvents and the compositions of perovskite precursors. Specially, there lacks a comprehensive study comparing different antisolvents used in low-temperature processed CsPbI from dimethylammonium-based precursors. In this work, we used three different antisolvents to control the growth of CsPbI films in a low-temperature (<200 °C) processed procedure and systematically compared the properties of resultant films. The green antisolvent ethyl acetate (EA) engineered CsPbI films exhibit improved morphology and crystallinity as well as reduced defects, compared with the counterparts processed without antisolvent or those with widely employed toxic antisolvents toluene and chlorobenzene. The EA antisolvent engineering results in efficient CsPbI perovskite solar cells with a champion power conversion efficiency of 8.8%. Our work thus provides a green and viable way to prepare high quality CsPbI perovskite films for optoelectronic applications.