Overcoming C₆₀-Induced Nonradiative Recombination via Interfacial Embedding of BiOBr Flakes in Inverted Perovskite Solar Cells

Abstract

The presence of C 60 -induced nonradiative recombination tends to deteriorate the overall efficiency of inverted perovskite solar cells (PSCs). To alleviate this problem, ultrathin BiOBr flakes possessing a unique self-induced internal electric field (SIEF) are embedded at the interface between perovskite and C 60 . SIEF, originating from the nonuniform charge distribution within the BiOBr lattice, tends to be perpendicular to the heterointerface of perovskite/C 60 because of the designed special (001) facet. This precise arrangement facilitates electron extraction and hole blocking, yielding a field-effect mediated passivation. Also, the desired surface atomic structure on the BiOBr(001) facet can chemically passivate the perovskite surface defects via the formation of a Pb–O bond. Combining these dual passivation effects with favorable band bending, the application of BiOBr boosts the efficiency of inverted PSCs up to 24.36% with a substantially improved long-term stability. This work demonstrates an effective way to overcome efficiency and stability limits of inverted PSCs.