MXene-Regulated Perovskite Vertical Growth for High-Performance Solar Cells

Defects at the interfaces of perovskite (PVK) thin films are the main factors responsible for instability and low photoelectric conversion efficiency (PCE) of PVK solar cells (PSCs). Here, a SnO2-MXene composite electron transport layer (ETL) is used in PSCs to improve interfacial contact and passivate defects at the SnO2/perovskite interface. The introduced MXene regulates SnO2 dispersion and induces a vertical growth of PVK. The lattice matching of MXene and perovskite suppresses the concentration of interfacial stress, thereby obtaining a perovskite film with low defects. Compared with SnO2-based device, the PCE of SnO2-MXene-based device is improved by 15 % and its short-circuit current is up to 25.07 mA cm(-2). Furthermore, unencapsulated device maintained about 90 % of its initial efficiency even after 500 h of storage at 30-40 % relative humidity in ambient air. The composite ETL strategy provides a route to engineer interfacial passivation between metal halide perovskites and ETLs.

Automated summary

In this study, a SnO2-MXene composite electron transport layer (ETL) was used to enhance interfacial contact and improve the efficiency of PVK solar cells by passivating defects at the SnO2/perovskite interface. The introduction of MXene effectively regulated SnO2 dispersion and facilitated vertical growth of PVK, resulting in a perovskite film with fewer defects. The PCE of the SnO2-MXene-based device showed a 15% improvement compared to the SnO2-based device, with a short-circuit current of 25.07 mA cm(-2). Additionally, the unencapsulated device retained about 90% of its initial efficiency after 500 hours of storage under ambient air conditions at 30-40% relative humidity. The use of the composite ETL strategy provides a promising approach for interfacial passivation in metal halide perovskites.