Extending the shelf-life of precursor solutions and inhibiting light-induced oxidation of iodides for achieving highly efficient and durable perovskite solar cells

Abstract

Durable shelf-life of precursor solutions is crucial for obtaining high-quality and stable perovskite films, which significantly affect the efficiency and stability of perovskite solar cells (PSCs). However, iodides in perovskites are easily oxidized by oxygen, especially under light exposure, reducing the shelf-life of precursor solutions and compromising perovskite films. Herein, we introduce sodium thiosulfate (ST) into perovskite inks to in situ tailor the crystallization of perovskites and suppress oxidation of iodides. As expected, this ST strategy effectively suppresses the iodide oxidation, and inhibits phase transitions and separation, thereby obtaining high-quality perovskite films with enhanced high crystallinity and reduced non-radiative recombination. Interestingly, the shelf-life of precursor solutions was extended over 60 days, and no phase transition can be found in perovskite films during 60 days of 1 sun light exposure. As a result, the champion ST-treated device achieves a PCE of 25.25% with a minimal voltage deficit of 0.35 V. More importantly, the unencapsulated devices demonstrate excellent long-term storage, thermal and light-soaking stability, delivering 93%, 85% and 85% of their original efficiencies after aging, respectively. This work provides an effective approach to extend the shelf-life of precursor solutions and improve the efficiency and operational stability of PSCs.