TiO2 and C60 transport nanolayers in optimized Pb-free CH3NH3SnI3-based perovskite solar cells

A Pb-free perovskite solar cell has been designed based on methylammonium (MA) tin-iodide (CH3NH3SnI3). The effect of electron transporting layer (ETL) material on the performance of the solar cell has been studied through substituting the ETL by TiO2 and C60 nanolayers. The energy level and charge carrier concentration profiles of the solar cells have been obtained for better understanding the involved mechanisms. The TiO2-containing solar cell showed the maximum power conversion efficiency (η) of ∼25.5 % at room temperature, with open circuit voltage, short circuit current density and filling factor of ∼1.06 V, 33.0 mA/cm2 and 73.1 %, respectively. Although the C60-containing perovskite solar cell presented a lower η with the value of ∼20.8 %, it could present a higher external quantum efficiency at NIR wavelength region, as compared to the TiO2-containing cell. These results can excite further investigation about the role of ETL nanomaterials in the performance of Pb-free perovskite solar cells.