Modifying SnO₂ with Polyacrylamide to Enhance the Performance of Perovskite Solar Cells

Modification of the charge transport layers is an effective way to improve charge transport and performance of perovskite solar cells (PSCs). The ions in the ionic compounds used for the modification of SnO₂ may migrate into the perovskite layer, which harms the stability of PSCs. In this work, a low-cost, water-soluble nonionic polymer polyacrylamide (PAM) is used to modify SnO₂. The addition of PAM improves the uniformity, wettability, and electron mobility of the SnO₂ film. Through the modification of SnO₂, the defects of perovskite films are reduced and the grain size is increased. Furthermore, the energy-level alignment at the SnO₂/perovskite interface is improved, which is beneficial to the transfer of electrons from perovskite to SnO₂. Finally, the power conversion efficiency (PCE) of PSCs formed from modified SnO₂ is enhanced to 22.59%. More importantly, the unencapsulated devices with modified SnO₂ retain 90% of the initial value after storage for more than 1000 h under a relative humidity of 50%. These results indicate that modifying SnO₂ using PAM is a promising strategy to improve the performance of PSCs.