Flexo-photovoltaic effect in MoS2

• DOI: 10.1038/s41565-021-00919-y
• Publication Date: 2021-06-17T16:06:53Z
• Authors: Jie Jiang; Zhizhong Chen; Yang Hu; Yu Xiang; Lifu Zhang; Yiping Wang; Gwo-Ching Wang; Jian Shi
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

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.