Boosting Performance of CsPbI3 Perovskite Solar Cells via the Synergy of Hydroiodic Acid and Deionized Water

Abstract

It remains challenging to fabricate high-efficiency all-inorganic perovskite solar cells (PSCs) at low temperature. Herein, the low-temperature preparation of high-efficiency CsPbI3 PSCs using hydroiodic acid (HI) and deionized water (H2O) as additives at synthetic temperature as low as 100 °C is proposed, which is beneficial for constructing even more complicated tandem or flexible solar cells. The additive of HI facilitates CsPbI3 to form a high-quality and smooth perovskite film at low temperature. The addition of an optimal amount of H2O further induces perovskite growth with larger grains and a smoother surface by the dissolution and recrystallization process in the grain boundary, which can suppress defects-induced nonradiative recombination. In this scenario, the corresponding device with structure of ITO/PEDOT:PSS/CsPbI3/PC61BM/Ag exhibits a high power conversion efficiency of 11.41% and the fill factor is increased from 62% to about 69%, compared with device based on CsPbI3 film without extra H2O treatment. The appropriate amount of H2O promotes the high-quality multigrain growth of the CsPbI3 film and reduces the internal defects, contributing to a significant improved charge collection efficiency. Therefore, this research work has paved a significant way to improving the quality of the all-inorganic perovskite film for highly efficient solar cells.