Multifunctional Passivation Strategy of Cationic and Anionic Defects for Efficient and Stable Perovskite Solar Cells

Abstract

The crystallinity of perovskite films is crucial for the performance and stability of perovskite solar cells (PSCs). Defects usually emerge in grain boundaries, leading to decomposition and non-radiative recombination of PSCs. Here, we present an effective additive engineering strategy to augment the long-term operation and stability of PSCs by doping a molecule with a symmetrical structure and bifunctional passivation, 2,5-thiophene dicarboxylic acid (TDCA), into the precursor solution. It is demonstrated that TDCA coordinates with the perovskite through hydrogen and Pb–O bonding, resulting in significantly enhanced crystallinity and defect passivation such as uncoordinated Pb2+ and I–. Meanwhile, the grain size is increased from 350 nm to about 650 nm for the perovskite, as well as the grain boundaries are reduced, which could inhibit the carrier non-radiative recombination loss. Consequently, the power conversion efficiency of champion PSCs is promoted from 19.31 to 22.78%. Furthermore, the enhanced crystallinity and defect passivation improve the wet-thermal stability of PSCs.