In situ energetics modulation enables high-efficiency and stable inverted perovskite solar cells

In contrast to conventional (n–i–p) perovskite solar cells (PSCs), inverted (p–i–n) PSCs offer enhanced stability and integrability with tandem solar cell architectures, which have garnered increasing interest. However, p–i–n cells suffer from energy level misalignment with transport layers, imbalanced transport of photo-generated electrons and holes, and significant defects with the perovskite films. Here we introduce tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB), a nonionic n-type molecule that, through hydrogen bonding and Lewis acid–base reactions with perovskite surfaces or grain boundaries, enables in situ modulation of perovskite energetics, effectively mitigating the key challenges of p–i–n PSCs. The p–i–n PSCs incorporating 3TPYMB achieve a certified quasi-steady-state power conversion efficiency of 24.55 ± 0.33%, with a reverse scan efficiency of 25.58%. They also exhibit exceptional stability, with unencapsulated devices retaining 97.8% of their initial efficiency after 1,800 h of continuous operation at maximum power point under N2 atmosphere, 1 sun illumination and 60 °C conditions.