Simultaneous Passivation of the SnO2/Perovskite Interface and Perovskite Absorber Layer in Perovskite Solar Cells Using KF Surface Treatment

Recently, SnO2 has been recognized as a promising electron transport layer (ETL) for perovskite solar cells (PSCs) due to its outstanding optoelectronic properties and low-temperature fabricating process. However, the detrimental defects formed at the SnO2/perovskite interface and within bulk perovskite films cause severe non-radiative recombination, limiting the further improvement of power conversion efficiencies (PCEs). Herein, we have demonstrated a facile surface treatment on SnO2 through KF modification to passivate defects at both regions simultaneously. F- ions reduce the detrimental hydroxyl group defects on the SnO2 surface effectively, resulting in improved crystallinity of perovskite films with a more favorable morphology. Meanwhile, a preferred energy level alignment between SnO2 and MAPbI(3) films is obtained, improving the carrier transport capability. Moreover, K+ ions can diffuse into the MAPbI(3) film, passivating the grain boundaries and intrinsic I- vacancy defects. Consequently, a significant increase in PCE from 18.47 to 20.33% is achieved for a MAPbI(3) PSC based on a SnO2/KF ETL, with negligible hysteresis and improved stability.

Automated summary

By modifying the surface of SnO2 with KF, defects at both the SnO2/perovskite interface and within bulk perovskite films were effectively passivated, leading to improved crystallinity and morphology of perovskite films, enhanced carrier transport capability, and a significant increase in PCE for PSCs.