Synthesis and characterization of Methylammonium tin iodide (CH3NH3SnI3) absorber layer for photovoltaic applications

In this work, a halide perovskite i.e. Methylammonium tin iodide (CH3NH3SnI3) has been synthesized through chemical route. This synthesis route involves two processes: i) Formation of SnI2, and ii) Formation of CH3NH3SnI3. After synthesis of CH3NH3SnI3 powder, thin films were deposited using doctor blade’s technique. The compositional, structural and morphological analysis of SnI2 powder, CH3NH3SnI3 powder and CH3NH3SnI3 thin films have been studied using EDXRF, XRD and FESEM respectively. The optical properties of the CH3NH3SnI3 films were also studied using UV–Vis spectrophotometer. The characterization of the thin films shows an optical bandgap of 1.4 eV with broad absorption, ranging between 300 nm and 900 nm. The morphological study of SnI2 powder shows rod-like structure with roughness average of 39.38 µm and that of perovskite powder and film shows flake-like structure with roughness average of 42.87 µm and 39.10 µm respectively. A new method of synthesis has been proposed. Also a brief characterization study of SnI2 powder, CH3NH3SnI3 powder and CH3NH3SnI3 thin films have been done, in order to analyse the photovoltaic properties of the thin films.