LAUSR

The photovoltaic performances of the perovskite solar cells are essentially dependent on the film quality of the absorbing layer which is greatly dependent on the deposition technique and the processing treatments employed. Here we are reporting the results on the growth of thin films of lead-free methylammonium bismuth iodide perovskites, by adopting a modified simple evaporation technique. In this technique, the methylammonium iodide films were deposited over the spin coated BiI3 thin-films with different evaporation temperatures (from 130 °C–210 °C) and the effect of methylammonium iodide vapour evaporation temperature on the surface quality of the as prepared perovskite thin films is studied. The structural and optical properties of these lead-free methylammonium bismuth iodide thin films were analysed using UV–vis Spectroscopy, XRD, AFM and SEM. The results reveal that the films grown around 150 °C and 170 °C are having uniform coverage, reduced roughness, and high transparency. They are highly crystalline in nature and exhibit high stability in the open atmosphere. However, increasing the evaporation temperature above 190 °C leads to deterioration of the quality of films.