Multifunctional organic molecule with synergistic modified SnO2 for efficient perovskite solar cells

Abstract

SnO₂ stands as a prominently employed material as electron transport layer (ETL) for perovskite solar cells (PSCs). Nevertheless, SnO₂ films prepared at low temperatures are accompanied by defects that will influent the transport of carriers at the interface, misalignment of energy levels, and the quality of thin perovskite film formation. Here, we introduce 4-aminobenzoic acid ethyl ester (4-AN), characterized by its carbonyl (C=O) and amino (-NH₂) groups, as a synergistic defect passivation agent on the surfaces of SnO₂ and perovskite films. This approach aims to enhance the electron transport properties of SnO₂. By optimizing the energy alignment between SnO₂ and perovskite, 4-AN facilitates more efficient extraction of interfacial carriers, while also promoting the crystalline quality of perovskite films and suppressing carrier recombination at the interface. The long alkyl chains at the end play an important role in relieving the interfacial contact and help to enhance the SnO₂/perovskite interfacial connection. Compared with pristine SnO₂, the PSCs based on 4-AN modified SnO₂ obtained an optimal efficiency of 21.83%, while the devices maintained 90% and 83% of their initial PCE after storage for 1000 h in an N₂ environment and humidity of 30-50%. This work provides valid insights for the development of novel interface modification materials.