Order–Disorder Phase Stabilization by Pressure‐Induced Charge Transfer Enhances the Ferroelectric Photovoltaic Effect in Multiferroic BaFe 4 O 7

作者：Jiayi Guan, Bihan Wang, Nana Li, Shang Peng, Ganghua Zhang, Limin Yan, Xuqiang Liu, Kai Zhang, Mingtao Li, Alpha T. N’Diaye, Qingyu Kong, Dongzhou Zhang, Xu Zhao, Ting Liu, Kejun Bu, Yuhong Mao, Gui Wang, Xujie Lü, Xiang Li, Tao Zeng, Wenge Yang · 发表于：Advanced Science · 年份：2025 · DOI：10.1002/advs.202511022 · 被引用次数：2 · 研究领域：Multiferroics and related materials、Ferroelectric and Piezoelectric Materials、Dielectric properties of ceramics

Abstract Multiferroic ferroelectric photovoltaic (FPV) materials, combining magnetic and ferroelectric properties, are of paramount importance for optoelectronic and photovoltaic applications. However, optimizing both the remanent polarization and the optical bandgap—key factors for enhanced FPV performance—presents a significant challenge due to their trade‐off. This work shows that pressure‐induced charge transfer between different metal sites can break this trade‐off. Above ≈20 GPa, charge transfer between different trivalent iron (Fe) sites in the multiferroic material BaFe 4 O 7 leads to Fe valence disproportionation, FeO 4 tetrahedra disorder, and Jahn–Teller distortion of FeO 6 octahedra. These changes reduce the bandgap, lower resistivity, and enhance ferroelectric polarization, resulting in a 2.5‐fold increase in photocurrent. Upon decompression, BaFe 4 O 7 retains an order–disorder structure, optimal ferroelectric and optical properties at ambient conditions. This work provides a novel pathway to simultaneously optimizing ferroelectricity and bandgap via pressure‐induced charge transfer, overcoming the traditional trade‐off in FPV materials, and offers a promising approach for developing high polarization performance, narrow‐bandgap FPV materials.