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.