Optical and Electrical Properties of Perovskite Variant (CH3NH3)2SnI6

In recent years, lead halide perovskites have emerged as excellent photovoltaic materials for solar power generation. However, because they are toxic and chemically unstable in air, lead-free perovskites are also being investigated. In this study, the perovskite variant (CH3NH3)2SnI6 was studied. Polycrystalline films of (CH3NH3)2SnI6 were prepared using the thermal evaporation method. The films had a direct band gap of 1.81 eV with a strong absorption coefficient of ∼7 × 104 cm–1. In addition, the films were n-type with a carrier concentration of ∼2 × 1015 cm–3 and an electron mobility of ∼3 cm2 V–1 s–1. Moreover, the conductivity was increased by a factor of 4 under simulated solar illumination (100 mW cm–2). These results indicate that (CH3NH3)2SnI6 is a lead-free optical semiconductor suitable for solar cell applications.