The theoretical Shockley–Queisser limit of photon–electricity conversion in a conventional p–n junction could be potentially overcome by the bulk photovoltaic effect that uniquely occurs in non-centrosymmetric materials. Using strain-gradient engineering, the flexo-photovoltaic effect, that is, the strain-gradient-induced bulk photovoltaic effect, can be activated in centrosymmetric semiconductors, considerably expanding material choices for future sensing and energy applications. Here we report an experimental demonstration of the flexo-photovoltaic effect in an archetypal two-dimensional material, MoS₂, by using a strain-gradient engineering approach based on the structural inhomogeneity and phase transition of a hybrid system consisting of MoS₂ and VO₂. The experimental bulk photovoltaic coefficient in MoS₂ is orders of magnitude higher than that in most non-centrosymmetric materials. Our findings unveil the fundamental relation between the flexo-photovoltaic effect and a strain gradient in low-dimensional materials, which could potentially inspire the exploration of new optoelectronic phenomena in strain-gradient-engineered materials.

传统 p-n 结中光子-电转换的理论 Shockley-Queisser 极限可能会被非中心对称材料中唯一出现的体光伏效应所克服。使用应变梯度工程，柔性光伏效应，即应变梯度诱导的体光伏效应，可以在中心对称半导体中被激活，极大地扩展了未来传感和能源应用的材料选择。_{在这里，我们通过使用基于由 MoS 2}和 VO ₂组成的混合系统的结构不均匀性和相变的应变梯度工程方法，报告了原型二维材料 MoS _{2中柔性光伏效应的实验演示。}. _{MoS 2}中的实验体光伏系数比大多数非中心对称材料高几个数量级。我们的研究结果揭示了柔性光伏效应与低维材料中的应变梯度之间的基本关系，这可能会激发对应变梯度工程材料中新光电现象的探索。