π-π Conjugation-mediated modulation of the PC₆₁BM/BCP interface enables mitigation of the light soaking effect in inverted perovskite solar cells

Inverted perovskite solar cells exhibit a prominent reversible light soaking effect, a key bottleneck for practical deployment, yet their underlying mechanisms remain elusive. Herein, this critical knowledge gap is addressed by probing the origin of the light soaking (LS) effect and developing targeted mitigation strategies. The PC₆₁BM/BCP interface is identified as the core determinant of LS-induced performance fluctuations and establishes a unified carrier dynamics framework involving interfacial charge accumulation and light-activated ion migration within the perovskite lattice. A TDPT-modified perovskite active layer is integrated with a TDPT-doped BCP electron transport layer, which synergistically narrows the electron extraction barrier, robustly suppresses halide ion migration, and enhances carrier transport. The optimized inverted device achieves a champion power conversion efficiency (PCE) of 25.68% and exceptional multi-dimensional stability, retaining over 85% of initial PCE after 1200 h of continuous 1-sun illumination, maintaining durability under 85 °C thermal stress, and resisting moisture-induced degradation under ambient conditions. This work clarifies the light soaking effect mechanisms and provides a generalizable interface-active layer co-optimization strategy, advancing the development of high-efficiency and durable perovskite photovoltaics.