Enhancement of bulk photovoltaic effect in topological insulators

TL;DR

This paper studies how the bulk photovoltaic effect in topological insulators is enhanced and reversed near a band inversion phase transition, using first-principles calculations and an analytical model.

Contribution

It demonstrates the enhancement and reversal of the bulk photovoltaic response near topological phase transitions through combined computational and analytical approaches.

Findings

Photocurrent reverses direction across the phase transition.

Magnitude of photocurrent is enhanced near the transition.

Phenomenon is robust across different material systems.

Abstract

We investigate the shift current bulk photovoltaic response of materials close to a band inversion topological phase transition. We find that the bulk photocurrent reverses direction across the band inversion transition, and that its magnitude is enhanced in the vicinity of the phase transition. These results are demonstrated with first principles DFT calculations of BiTeI and CsPbI$_3$ under hydrostatic pressure, and explained with an analytical model, suggesting that this phenomenon remains robust across disparate material systems.