2-Methoxy Ethanol-Driven Solvent Engineering of Cs3Bi2I9 Perovskite Films andits Impact on Lead Free Perovskite Solar Cell Devices

The development of compact perovskite thin films is essential for fabrication of high-performance solar cell devices. Solvent engineering stands out as a promising method to achieve such films, providing a straightforward approach with significant control over the film formation process. In this study, we employed a solvent engineering approach to attain compact and uniform growth in Cs₃Bi₂I₉ films. We incorporated 2-methoxy ethanol (2-ME) as an additive in N, N-Dimethylformamide (DMF) solvent. The resulting perovskite films exhibited enhanced crystallinity and absorbance compared to films prepared with DMF alone, particularly when using a DMF:2-ME mixing ratio of 4:1. Moreover, we successfully fabricated lead-free, flexible perovskite solar cell devices using a solution processing technique. The photovoltaic performance of estimated and efficiency of devices prepared with 4:1 ratio of DMF:2-ME exhibited efficiency of ~1.56%.