Enhanced efficiency and stability of planar perovskite solar cells using SnO2:InCl3 electron transport layer through synergetic doping and passivation approaches

There are many defect states at the interface between SnO2 and perovskite due to the preparation process and the lattice mismatch. These defects will trap photo-generated carriers, resulting in low carrier extraction efficiency and loss of device stability. Many researches are underway to further improve the performance of perovskite solar cells (PSCs) based on SnO2 electron transport layer (ETL), including doping of ETL and effective passivation of interface defects. Here, the SnO2:InCl3 ETL is used in planar perovskite solar cells to simultaneously dope ETL and passivate the defects at the ETL/perovskite interface. First, Cl ions can passivate the defects on the SnO2 surface, and part of the chloride ions can also diffuse into the perovskite to passivate the grain boundaries. Additionally, In ions themselves are suitable dopants and can provide better doping performance for SnO2. The result shows that the simultaneous ETL doping and interface passivation result in a significant increase of PCE from 19.1% to 20.8% due to the enhancement of short-circuit current density. This method expands the ETL/perovskite interface optimization work by using anions and cations for passivation and doping, respectively, and has some inspiration for the delivery of high efficiency and stable planar structure PSCs based on SnO2 ETL.