Superior performance of silver bismuth iodide photovoltaics fabricated via dynamic hot-casting method under ambient conditions

Abstract

Bismuth-based ternary halides have recently gained a lot of attention as lead-free perovskite materials. However, photovoltaic performances of these devices remain poor, mostly due to their low-dimensional crystal structure and large bandgap. Here, a dynamic hot casting technique to fabricate silver bismuth iodide-based perovskite solar cells under an ambient atmosphere with power conversion efficiencies above 2.5% is demonstrated. Silver bismuth iodides are 3D analogs of complex ternary bismuth halides with a suitable bandgap for a single junction solar cell. As far as it is known, these results represent the highest efficiency for solution processed air-stable lead-free perovskite solar cells. The enhanced solar cell performance via this dynamic hot casting technique can be attributed to long carrier lifetimes, micrometer-sized crystalline grains, and pinhole free thin-film formation with uniform morphology. This work provides a new direction for fabrication of solution-processed lead-free perovskite solar cells with a rapid fabrication strategy irrespective of the processing environment.