Modulating vacancy-related defects and hole extraction via a multifunctional additive for high-performance perovskite solar cells

Due to the unique characteristics of solution preparation and rapid crystal growth, perovskite solar cells may exhibit various kinds of defects that ultimately impact their photovoltaic performance and stability. Here, a multifunctional additive, potassium trifluoromethanesulfonate (KTFS), is introduced into lead iodide precursor solution. Due to the trifluoromethanesulfonate anions, a positive work function shift (more p type) is observed, which benefits the extraction of holes. The potassium cation can occupy the lattice gaps and effectively inhibit ion migration, and the formation energy of iodine vacancy and lead vacancy defects are increased according to calculation results. As a result, KTFS-modified perovskite solar cell devices show a champion efficiency up to 23.96% as well as over 1,000-h stability.