Green solvent engineering for environment-friendly fabrication of high-performance perovskite solar cells

Antisolvent-assisted crystallization is a common process to fabricate high-performance perovskite solar cells (PSCs). At present, toxic organic solvents such as toluene or chlorobenzene have been used as typical antisolvents to fabricate compact perovskite absorber layer for a device, but their impact to environment or human/animal health has remained a challenge to be resolved for commercialization of PSCs. In this study, we suggest (R)-(+)-limonene and 2-methyltetrahydrofuran as eco-compatible and less-toxic antisolvents for preparing high-quality perovskite absorber layer in the inverted PSCs. The green antisolvents afford smooth, compact, less-defect, and full coverage perovskite films, comparable to the typical halogenated antisolvent-processed perovskite films, delivering a PCE up to 18.04% in CH3NH3PbI3-based device. The green antisolvent also demonstrated promising PCEs of 17.85%, 13.46%, and 10.04% in CH3NH3PbI3, CsPbI2Br, and BA2MA3Pb4I13-based PSCs accompanied with a halogen-free solvent-processed PC61BM layer. This work demonstrates a great potential of green antisolvents as a universal approach in obtaining high-quality perovskite films for fabricating high-efficiency PSCs.