Synergistic defect passivation and energy band reconstruction via LiH 2 PO 4 additive for efficient inverted perovskite solar cells

Inverted perovskite solar cells (PSCs) are fundamentally constrained by non-radiative recombination and energy-level mismatches. Herein, we introduce lithium dihydrogen phosphate (LiH2PO4) as a multifunctional precursor additive to regulate the crystallization kinetics and electronic structure of perovskite films. We demonstrate that LiH2PO4 not only promotes highly (100)-textured grain growth and passivates deep-level defects but also induces a global energy band reconstruction. By correlating X-ray photoelectron spectroscopies and ultraviolet photoelectron spectroscopies, we disclose that the anomalous, simultaneous increase in core-level binding energies originates from a Fermi-level-driven rigid band shift coupled with the formation of a robust interfacial dipole. This dual-action mechanism effectively suppresses non-radiative recombination and eliminates charge extraction barrier. Consequently, the optimized inverted PSCs achieve a champion power conversion efficiency of 24.11%, along with enhanced open-circuit voltage, fill factor, and long-term environmental stability.