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

•The effect of TiO2 and C60 materials as transport layers on the performance of lead-free CH3NH3SnI3-based perovskite solar cells has been studied.•The TiO2- and C60-based cells showed power conversion efficiencies of 25.5 and 20.8%, respectively.•The Influence of defects on the performance of the solar cells has been investigated.