Direct evidence for bulk photovoltaic charge transport in a ferroelectric polycrystalline film

The anomalous or bulk photovoltaic (BPV) effect in ferroelectrics is not subject to the Shockley-Queisser limit capping the efficiency of interface-based semiconductor photovoltaics. Therefore, it has been widely explored for applications in photovoltaic energy harvesters, non-destructive read-out mechanisms for data storage, or photorefractive thin-film devices. However, all investigations have so far been restricted to single crystals and epitaxial thin films; there is yet no direct evidence of a bulk photovoltaic charge transport in polycrystalline thin films, which would open a much larger range of economical applications. This study demonstrates the bulk nature of the photovoltaic effect in polycrystalline solution-processed BiFeO3 thin films. A light-polarization-dependent photocurrent is shown. Combined with the dependence of the photocurrent on the poling state of the film and the light intensity, as well as the scaling of open circuit voltage with electrode distance, this clearly indicates that the charge carrier separation relies on the BPV effect. (c) 2022 The Authors. Published by Elsevier Ltd on behalf of Acta Materialia Inc.& nbsp;