First-Principles Calculation of the Bulk Photovoltaic Effect in the Polar Compounds LiAsS$_\text{2}$, LiAsSe$_\text{2}$, and NaAsSe$_\text{2}$

TL;DR

This study uses first-principles calculations to evaluate the bulk photovoltaic effect in polar compounds LiAsS2, LiAsSe2, and NaAsSe2, revealing their high potential for photovoltaic applications due to large shift current responses.

Contribution

The paper provides the first computational analysis of the shift current response in these specific polar compounds, highlighting their superior photovoltaic responses compared to known materials.

Findings

Photovoltaic responses exceed BiFeO3 by 10-20 times.

High shift current linked to p states at band edges and band dispersion.

Materials have low band gaps (<2 eV) suitable for photovoltaics.

Abstract

We calculate the shift current response, which has been identified as the dominant mechanism for the bulk photovoltaic effect, for the polar compounds LiAsS$_\text{2}$, LiAsSe$_\text{2}$, and NaAsSe$_\text{2}$. We find that the magnitudes of the photovoltaic responses in the visible range for these compounds exceed the maximum response obtained for BiFeO$_\text{3}$ by 10 - 20 times. We correlate the high shift current response with the existence of $p$ states at both the valence and conduction band edges, as well as the dispersion of these bands, while also showing that high polarization is not a requirement. With low experimental band gaps of less than 2 eV and high shift current response, these materials have potential for use as bulk photovoltaics.