Flexo-photovoltaic effect in MoS2

A strain-gradient approach induced by the phase-change transition enables the observation of the flexo-photovoltaic effect in MoS2. 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.

Automated summary

The flexo-photovoltaic effect induced by strain-gradient engineering enables the activation of bulk photovoltaic effect in centrosymmetric semiconductors, expanding material choices for future sensing and energy applications. The experimental demonstration in MoS2 reveals the potential for new optoelectronic phenomena in strain-gradient-engineered materials.