Flexoelectric Suppression of Interfacial Carrier Loss in BaTiO ₃ Thin‐Film Bulk Photovoltaic Systems

Bulk photovoltaic (BPV) effects in ferroelectric oxides have attracted significant attention for their potential to circumvent the bandgap‐limited open‐circuit voltage of conventional solar cells. However, the practical realization of thin‐film BPV devices remains challenging due to interfacial carrier loss, which severely limits photocurrent. Here, we demonstrate in single‐crystalline BaTiO 3 thin films that mechanically induced flexoelectric strain gradients effectively suppress interfacial carrier recombination. By combining systematic loading experiments with self‐consistent electrostatic modeling, we show that strain gradients reconfigure interfacial electrostatics, thereby enhancing the local drift field. This flexoelectric modulation substantially increases photocurrent by mitigating interfacial carrier loss, resulting in a ∼35‐fold (3557%) increase in photocurrent. Our modeling framework quantitatively captures the thickness‐dependent carrier extraction and further reveals that structural, electrostatic, and materials‐specific parameters cooperatively govern the extraction efficiency in interface‐limited BPV systems. Therefore, these results provide a physically grounded pathway to interfacial loss engineering in thin‐film BPV systems through flexoelectric modulation.