In-Plane Bulk Photovoltaic Effect in a MoSe<sub>2</sub>/NbOI<sub>2</sub> Heterojunction for Efficient Polarization-Sensitive Self-Powered Photodetection.

Huang, Xiong; Wang, Qi; Song, Kejian; Hu, Qichuan; Zhang, Huaihao; Gao, Xingsen; Long, Mingzhu; Xu, Jinyou et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Two-dimensional ferroelectric materials can generate a bulk photovoltaic effect, making them highly promising for self-powered photodetectors. However, their practical application is limited by a weak photoresponse due to a weak transition strength and wide band gap. In this study, we construct a van der Waals heterojunction using NbOI<sub>2</sub>, which has significant in-plane polarization, with a highly absorbing MoSe<sub>2</sub> layer. We observe ultrafast hole transfer from MoSe<sub>2</sub> to NbOI<sub>2</sub> within 0.4 ps and electron transfer in the opposite direction within 3.8 ps, facilitating efficient charge dissociation and extraction. Applying a direct current electric field poling modulates the ferroelectric domains in NbOI<sub>2</sub>, enhancing the bulk photovoltaic effect. This results in one of the highest responsivities for self-powered photodetectors (101.3 mA/W) at 0 V bias alongside excellent polarization sensitivity (∼7.58). This work advances the understanding of self-powering mechanisms via the bulk photovoltaic effect and proposes new strategies for future self-powered devices.