Substituent-Tuned Dipole and Coordination Geometry in Methoxybenzohydrazides for Stable and Efficient Inverted Perovskite Solar Cells

Interfacial energy alignment and defect passivation are critical for advancing the efficiency and stability of inverted perovskite solar cells. Herein, we report a molecular design strategy using methoxybenzoylhydrazines (MBHs) as synergistic bifunctional modulators to simultaneously modulate interfacial energetics and passivate defects. By systematically varying the number and position of the methoxy substituents on the phenyl ring, we elucidate how structural motifs govern the dipole strength, coordination behavior, and interfacial compatibility. Interestingly, increasing the number of electron-donating groups does not guarantee a larger dipole moment, highlighting the pivotal role of the substituent arrangement and intramolecular conjugation. Devices with MBHs achieve a champion power conversion efficiency of 25.8% with excellent operational stability, retaining over 93% efficiency after 1500 h at 85 °C under maximum power point tracking. These findings demonstrate how substituent-directed dipole engineering and multidentate interactions can be harnessed to overcome key interfacial challenges in perovskite photovoltaics.