Managing film crystallization via low-toxic antisolvents: stabilizing Ag3BiI6 perovskite-like solar cells under ambient conditions†

The intense pursuit of lead-free perovskite materials for cleaner and more affordable energy led to the discovery of silver(I)–bismuth(III) halides. These materials have a perovskite-type electronic structure that is ideal for optoelectronic applications. Despite the efforts to fabricate eco-friendly devices with these absorbers, a required surge in R&D is still needed to completely eliminate toxicity, particularly with respect to the solvents and antisolvents used in the process. This study introduces a low-toxic antisolvent formulation that could significantly facilitate controlled nucleation and growth, yielding pinhole-free, sufficiently loaded Ag₃BiI₆ absorber films. Additionally, the issues of high hygroscopicity and migration of the p-dopant Li-TFSI in the hole-transport material have been addressed, resulting in substantial device stability. A detailed investigation of the charge-carrier dynamics carried out at the interface of the photoabsorber and charge-transport layers provided insights into the relationships among the processing, structure, properties, and performance of this device, thus paving the way for the extended use of these approaches in other perovskite devices. Complete fabrication of this device under ambient conditions and low temperature annealing showed its promise for robust and large-scale deployment.