Trap engineering using oxygen-doped graphitic carbon nitride for high-performance perovskite solar cells

Abstract

Trap-assisted non-radiative recombination is one of the main energy loss pathways in metal halide perovskite solar cells (PVSCs). Here in this work, oxygen-doped graphitic carbon nitride (g-C₃N₄-O) is introduced into the commonly used SnO₂ electron transport layer (ETL) as an additive to engineer the traps at the ETL/perovskite interface. The interaction between g-C₃N₄-O and SnO₂ could effectively and simultaneously mitigate the uncoordinated Sn dangling bonds and the –OH groups, which are the two dominant deep-traps at the ETL/perovskite interface. Trap-engineered PVSCs show optimized electrical properties with matched energy band alignment, improved electron transport and extended carrier lifetime. As a result, binary PVSCs modified with g-C₃N₄-O achieve a champion power conversion efficiency of over 21% and demonstrate high environmental stability.