Stability Improvement Of Tin-Based Halide Perovskite By Precursor-Solution Regulation With Dual-Functional Reagents

Tin-based halide perovskites have attracted great attention in the perovskite solar cells (PSCs) community with their suitable band gaps, excellent optoelectronic properties, and non-toxicity. However, because of their poor chemical stability, it is challenging to fabricate highly stable and efficient tin PSCs (TPSCs). In this study, the origin of the Sn2+ oxidation ahead of film formation is concentrated on, and it is found that the ionization of SnI2 in precursor plays a decisive role. Accordingly, SnI2 dissociation and the subsequent Sn2+ oxidation can be restricted in precursor by employing reductive complexes as additives. This dual-functional source-regulating strategy effectively helps prepare high-quality perovskite films with low Sn4+ defect densities. As a result, the unencapsulated TPSCs show a considerable power-conversion efficiency of 10.03% (certified 9.38%) and maintain 90% of its initial efficiency after 1000 h of light aging testing.