Study on the interface defects of eco-friendly perovskite solar cells

Because of the rapid improvement of perovskite (PSK) solar cells (PSCs), they are considered the most promising photovoltaic devices nowadays. This improvement is mainly observed in the lead (Pb)-based PSCs, though Pb is a highly toxic material. Due to this toxicity, Pb-free perovskites have drawn considerable attention as the substitute for Pb-based perovskites. Performances of these Pb-free PSCs depend on the interfaces between the perovskite layer and electron transport layer (ETL) and between the perovskite absorber layer and hole transport layer (HTL). This research focuses on the investigation of these interfaces in different PSCs, in which MASnI3, MAGeI3, and Cs3Bi2I9 perovskites are used the absorber layer. The effect of defect density, defect position, and the capture cross-section area of electrons and holes for these interfaces on power conversion efficiency are considered in this study through simulation conducted by the SCAPS-1D simulator. A significant effect of defect density in interfaces has been observed. Deep level traps have been identified as one of the performance degradation reasons. On PCE, the effect of ETL/PSK interface properties is much more significant than the PSK/HTL interface effect. Simulated results would enlighten the researchers to choose the perfect Pb-free perovskite for solar cells that will show greater tolerance against interface defects. Besides, these findings will be helpful in considering the optimum values of interface defect parameters of various types of practical PSCs.