Highly Efficient and Stable Inverted Perovskite Solar Cell Obtained via Treatment by Semiconducting Chemical Additive.

The addition of chemical additives is considered as a promising approach for obtaining high-quality perovskite films under mild conditions, which is essential for both the efficiency and the stability of organic-inorganic hybrid perovskite solar cells (PeSCs). Although such additive engineering yields high-quality films, the inherent insulating property of the chemical additives prevents the efficient transport and extraction of charge carriers, thereby limiting the applicability of this approach. Here, it is shown that organic conjugated molecules having rhodanine moieties (i.e., SA-1 and SA-2) can be used as semiconducting chemical additives that simultaneously yield large-sized perovskite grains and improve the charge extraction. Using this strategy, a high power conversion efficiency of 20.3% as well as significantly improved long-term stability under humid air conditions is achieved. It is believed that this approach can provide a new pathway to designing chemical additives for further improving the efficiency and stability of PeSCs.