Impact of electrodes on the extraction of shift current from a ferroelectric semiconductor SbSI

TL;DR

This study demonstrates that electrode choice significantly influences shift current extraction in ferroelectric SbSI, revealing nearly bias-free photocurrent and fundamental design principles for energy-harvesting devices based on shift current effects.

Contribution

It shows that selecting high work function electrodes enhances shift current in SbSI and provides insights into device design for dissipation-less photovoltaic applications.

Findings

Photocurrent is dramatically enhanced with high work function electrodes.

Nearly constant zero-bias photocurrent observed despite mobility variations.

Shift current operates as a majority carrier device, distinct from conventional photovoltaics.

Abstract

Noncentrosymmetric bulk crystals generate photocurrent without any bias voltage. One of the dominant mechanisms, shift current, comes from a quantum interference of electron wave functions being distinct from classical current caused by electrons' drift or diffusion. The dissipation-less nature of shift current, however, has not been fully verified presumably due to the premature understanding on the role of electrodes. Here we show that the photocurrent dramatically enhances by choosing electrodes with large work function for a $p$-type ferroelectric semiconductor SbSI. An optimized device shows a nearly constant zero-bias photocurrent despite significant variation in photocarrier mobility dependent on temperature, which could be a clear hallmark for the dissipation-less nature of shift current. Distinct from conventional photovoltaic devices, the shift current generator operates as a majority carrier device. The present study provides fundamental design principles for energy-harvesting and photo-detecting devices with novel architectures optimal for the shift current photovoltaic effect.