Colossal Bulk Photovoltaic Effect in a Weyl Semimetal

TL;DR

This paper reports the discovery of the largest bulk photovoltaic effect in a Weyl semimetal, demonstrating ultrafast, efficient light-to-electricity conversion with potential applications in energy and sensing.

Contribution

It presents the first room-temperature observation of a significant BPVE in a Weyl semimetal, linking topology to photovoltaic response and enabling new device possibilities.

Findings

Largest observed BPVE in a Weyl semimetal

Room temperature mid-IR BPVE detection in TaAs

Symmetry analysis confirms intrinsic shift current

Abstract

Broadband, efficient and fast conversion of light to electricity is crucial for sensing and clean energy. Here we reveal the largest observed bulk photo-voltaic effect (BPVE), an intrinsic mechanism predicted to be ultrafast and exceed the Shockley-Quiesser limit. This discovery results from combining recent developments in the connection of BPVE to topology, Weyl semimetals and focused-ion beam fabrication. Our room temperature observation of the first BPVE in the mid-IR, is enabled by microscopic devices of the Weyl semimetal TaAs. Detailed symmetry analysis enables unambiguous separation of this response from competing photo-thermal effects. The size and wavelength range of the shift current offers new opportunities in optical detectors, clean energy, and topology, while directly demonstrating the utility of Weyl semimetals for applications.