Acousto-drag photovoltaic effect by piezoelectric integration of two-dimensional semiconductors

TL;DR

This paper demonstrates a novel acousto-electric photovoltaic effect in layered MoSe2 using surface acoustic waves, enabling efficient, symmetry-independent light-to-electricity conversion through piezoelectric integration.

Contribution

It introduces a new acousto-electric photovoltaic mechanism in 2D semiconductors driven by surface acoustic waves, independent of crystal symmetry.

Findings

Surface acoustic waves generate zero-bias photocurrent in MoSe2.

Photocurrent results from band modulation and carrier dragging by SAW.

The effect suppresses recombination, enhancing photoresponse.

Abstract

Light-to-electricity conversion is crucial for energy harvesting and photodetection, requesting efficient electron-hole pair separation to prevent recombination. Traditional junction-based mechanisms using built-in electric fields fail in non-barrier regions. Homogeneous material harvesting under photovoltaic effect is appealing but only realized in non-centrosymmetric systems via bulk photovoltaic effect. Here we report the realization of photovoltaic effect by employing surface acoustic waves (SAW) to generate zero-bias photocurrent in a conventional layered semiconductor MoSe2. SAW induces periodic modulation to electronic bands and drags the photoexcited pairs toward the travelling direction. The photocurrent is extracted by a local barrier. The separation of generation and extraction processes suppresses recombination and yields large nonlocal photoresponse. We distinguish acousto-electric drag and electron-hole pair separation effect by fabricating devices of different configurations. The acousto-drag photovoltaic effect, enabled by piezoelectric integration, offers an efficient light-to-electricity conversion method, independent of semiconductor crystal symmetry.