Large Bulk Piezophotovoltaic Effect of Monolayer $2H$-MoS$_2$

TL;DR

This paper investigates the bulk photovoltaic effect in monolayer MoS₂, revealing a distortion that significantly enhances the shift current, and proposes electric field-induced polarization as a new way to engineer this effect.

Contribution

It introduces a simple automated method to identify distortions that enhance the shift current in monolayer MoS₂, expanding the toolkit for photovoltaic material design.

Findings

Distortion in monolayer MoS₂ dramatically increases the shift current.

Overlap of shift vector and transition intensity distributions is key to enhancement.

Electric field can induce the distortion via the converse piezoelectric effect.

Abstract

The bulk photovoltaic effect in noncentrosymmetric materials is an intriguing physical phenomenon that holds potential for high-efficiency energy harvesting. Here, we study the shift current bulk photovoltaic effect in the transition metal dichalcogenide MoS$_2$. We present a simple automated method to guide materials design and use it to uncover a distortion to monolayer $2H$-MoS$_2$ that dramatically enhances the integrated shift current. Using this distortion, we show that overlap in the Brillouin zone of the distributions of the shift vector (a quantity measuring the net displacement in real space of coherent wave packets during excitation) and the transition intensity is crucial for increasing the shift current. The distortion pattern is related to the material polarization and can be realized through an applied electric field via the converse piezoelectric effect. This finding suggests an additional method to engineer the shift current response of materials to augment previously reported methods using mechanical strain.