Tuning Terminal Groups of Hole‐Selective Materials to Suppress Nonradiative Recombination in Inverted Perovskite Solar Cells

The performance of perovskite solar cells (PSCs) is critically constrained by nonradiative recombination at the perovskite/charge-extraction interfaces, which limits their approach to the thermodynamic efficiency limit. Although extensive efforts have focused on passivating surface defects, the role of interfacial energy-level mismatch in driving nonradiative losses remains insufficiently understood. In this work, we investigate the impact of valence band maximum (VBM) offsets between hole-selective layers and perovskites on the nonradiative recombination losses in PSCs by tailoring the terminal groups of hole-selective materials (HSMs). Our findings reveal that the minimized energetic barrier at the hole-selective interface is conducive to achieving the maximum quasi-Fermi level splitting (QFLS) in perovskites. Through precise energy-level alignment at the buried HSM/perovskite interface via terminal group engineering, we achieved high power conversion efficiency (PCE) of 26.88% and 21.87% for PSCs based on 1.53 and 1.72 eV perovskites, respectively, with open-circuit voltage (VOC) value reaching 95% and 91% of their Shockley-Queisser limit, respectively. Our results provide valuable insights for designing hole-selective molecules and elucidating the relationship between nonradiative recombination losses and energy level alignment across different perovskite compositions.