Reducing Energy Disorder for Efficient and Stable Sn-Pb Alloyed Perovskite Solar Cells

Sn-Pb alloyed perovskites have drawn considerable attention because of their appropriate band gap for both single-junction and multi-junction tandem photovoltaics, but the easy-formation of energy disorder still limits their practical applications. Here, we report that the combination of 1-bromo-4-(methylsulfinyl) benzene (BBMS) and SnF2 greatly reduced the Urbach energy of perovskite films, and largely restrained the oxidation of Sn2+. With the help of density functional theory calculations, we clarified the interactions between BBMS and perovskite were responsible for the improvements. As a result, a high efficiency of > 22 % was obtained for the Sn-Pb alloy-based solar cells treated by BBMS and SnF2. More importantly, the BBMS-treated device (devices) demonstrated outstanding stability, retaining 98 % of its original efficiency after heating at 60 degrees C for 2660 h under N-2.

Automated summary

This study found that combining 1-bromo-4-(methylsulfinyl) benzene (BBMS) and SnF2 can significantly reduce the energy disorder in Sn-Pb alloyed perovskites and inhibit the oxidation of Sn2+. The solar cells treated with BBMS and SnF2 showed high efficiency and outstanding stability.