An effective approach of vapour assisted morphological tailoring for reducing metal defect sites in lead-free, (CH3NH3)3Bi2I9 bismuth-based perovskite solar cells for improved performance and long-term stability

We have used vapour assisted solution process technique to prepare lead-free, non-toxic bismuth-based perovskite solar cells using BiI3 and BiI3 on reaction with CH3NH3I vapours (MAI(v)) for different reaction times. By this stoichiometric tailoring and fine-tuning bismuth-based perovskite have shown record breaking performance with 3.17% hysteresis free efficiency (world record so far for CH3NH3BiI3 based perovskite solar cells) that retains for more than 60 days (>1440 h) under continuous 1 sun (Am1.5 G) illumination showing a breakthrough in the long-term stability. The figure represents BiI3 and multicolour absorber layers formed on reaction of BiI3 with MAI(v) for different reaction time and utilized in making solar devices.146