2026-06-23 理化学研究所,東北大学,東京大学,住友化学株式会社
強誘電性ハライドペロブスカイト薄膜への可視光照射による光電流発生の概念図
＜関連情報＞
- https://www.riken.jp/press/2026/20260623_1/index.html
- https://www.pnas.org/doi/10.1073/pnas.2602252123
強誘電性ハロゲン化物ペロブスカイトのシフト電流応答における記録的な高値のグラス係数 Record-high Glass coefficient in the shift current response of a ferroelectric halide perovskite
Koma Miki, Masao Nakamura, Asahi Yamada, +6 , and Masashi Kawasaki
Proceedings of the national Academy of Sciences Published:June 22, 2026
DOI:https://doi.org/10.1073/pnas.2602252123
Significance
Shift current is a second-order nonlinear optical effect arising from the change in the quantum geometry of wave functions, and provides a photovoltaic mechanism fundamentally distinct from conventional junction-based photovoltaics. CsGeI3 is a lead-free ferroelectric halide perovskite with an ideal bandgap for solar absorption, yet experimental progress has been hindered by the lack of high-quality thin films. Here, we report epitaxial CsGeI3 thin films grown by molecular beam epitaxy and a gigantic shift current response. The normalized magnitude exceeds prior reports by more than an order of magnitude, establishing ferroelectric halide perovskites as a benchmark platform for quantum-geometry-driven optoelectronics.
Abstract
Ferroelectric halide perovskites provide a fertile platform for optoelectronic functions based on the bulk photovoltaic effect, where broken inversion symmetry couples with quantum geometry of wave functions. The most prominent manifestation is the shift current, second-order nonlinear photocurrent arising from change in the Berry connection during optical transitions. Here we report a gigantic shift current response in epitaxial thin films of a lead-free ferroelectric halide perovskite CsGeI3. High-quality films grown by molecular beam epitaxy exhibit clear hallmarks of shift current, including spectral sign reversals, light-polarization dependence, and reversible electric-field modulation associated with switchable ferroelectric polarization. Remarkably, the normalized shift current magnitude surpasses those ever reported for other compounds by more than an order of magnitude, establishing a benchmark for bulk photovoltaic performance. These results identify ferroelectric halide perovskites as a powerful platform for exploring quantum-geometry-driven photoresponses and open a pathway toward next-generation photovoltaic and nonlinear optoelectronic technologies beyond the conventional junction-based architectures.
