近日，香港大学的Lain-Jong Li及其研究团队取得一项新进展。经过不懈努力，他们揭示边缘半金属接触增强过渡金属二硫化物的体光伏效应。相关研究成果已于2025年1月2日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队一项重要突破，即通过采用铋半金属电极构建边缘接触（EC）结构，显著增强了3R-MoS₂中的体光伏效应（BPVE）。与通常使用的顶接触（TC）结构形成鲜明对比，边缘接触的金属与边缘和基底紧密结合，能对3R-MoS₂施加显著的拉伸应变，并且这种侧向接触结构使得光线能够完全访问底层可达区域的面内极化，从而使光电流中的BPVE增强了100倍以上。

研究人员进一步设计了3R-MoS₂/WSe₂异质结，以展示BPVE与传统光伏效应的建设性耦合，这表明它们在光电探测器和光伏器件中具有巨大潜力。

据悉，具有非中心对称结构的氧化物材料展现出体光伏效应（BPVE），但其电池效率较低。近年来，有报道称，在具有不对称性诱导自发极化的二维（2D）层状结构和堆叠结构中观察到了相对较大的体光伏效应系数。

附：英文原文

Title: Boosting bulk photovoltaic effect in transition metal dichalcogenide by edge semimetal contact

Author: Qiao, Shuang, Liu, Jihong, Yao, Chengdong, Yang, Ni, Zheng, Fangyuan, Meng, Wanqing, Wan, Yi, Chow, Philip C. Y., Ki, Dong-Keun, Zhang, Lijie, Shi, Yumeng, Li, Lain-Jong

Issue&Volume: 2025-01-02

Abstract: Oxide materials with a non-centrosymmetric structure exhibit bulk photovoltaic effect (BPVE) but with a low cell efficiency. Over the past few years, relatively larger BPVE coefficients have been reported for two-dimensional (2D) layers and stacks with asymmety-induced spontaneous polarization. Here, we report a crucial breakthrough in boosting the BPVE in 3R-MoS₂ by adopting edge contact (EC) geometry using bismuth semimetal electrode. In clear contrast to the typically used top contact (TC) geometry, the EC metal which strongly adheres to the edges and the subtrates can induce a pronounced tensile strain to the 3R-MoS₂, and the lateral contact geometry allows to completely access to in-plane polarization from underneath layers reachable by light, leading to >100 times of BPVE enhancement in photocurrent. We further design a 3R-MoS₂/WSe₂ heterojunction to demonstrate constructive coupling of BPVE with the conventional photovoltaic effect, indicating their potential in photodetectors and photovoltaic devices.

DOI: 10.1038/s41377-024-01691-z

Source: https://www.nature.com/articles/s41377-024-01691-z