Reconsidering evidence of shift current in a ferroelectric charge-transfer complex

TL;DR

This paper critically examines previous claims of shift current in a ferroelectric charge-transfer complex, arguing that the experimental evidence does not conclusively demonstrate the shift current mechanism due to ambiguities in data interpretation.

Contribution

It provides a critical analysis showing that existing experimental data cannot definitively confirm the presence of shift current in TTF-CA.

Findings

Experimental data is insufficient to unambiguously identify shift current.

The analysis challenges previous interpretations of the photovoltaic effects.

Distinguishing between ballistic and shift contributions requires more precise measurements.

Abstract

In Nakamura et al.[1], the authors present evidence of shift current in the electronic ferroelectric tetrathiafulvalene-$p$-chloranil (TTF-CA). Since the bulk photovoltaic current in non-centrosymmetric crystals has two contributions, namely the ballistic and shift, we explain why the experimental data and analysis presented by the authors does not permit unambiguous identification of shift current, and is not consistent with the mechanism of shift.