Origin of the switchable photocurrent direction in BiFeO3 thin films

Yaqiong Wang, Matyas Daboczi, Man Zhang, Joe Briscoe, Ji Seon Kim, Haixue Yan, Steve Dunn

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
1 Downloads (Pure)

Abstract

We report external bias driven switchable photocurrent (anodic and cathodic) in 2.3 eV indirect band gap perovskite (BiFeO3) photoactive thin films. Depending on the applied bias our BiFeO3 films exhibit photocurrents more usually found in p- or n-type semiconductor photoelectrodes. In order to understand the anomalous behaviour ambient photoemission spectroscopy and Kelvin-probe techniques have been used to determine the band structure of the BiFeO3. We found that the Fermi level (Ef) is at −4.96 eV (vs. vacuum) with a mid-gap at −4.93 eV (vs. vacuum). Our photochemically determined flat band potential (Efb) was found to be 0.3 V vs. NHE (−4.8 V vs. vacuum). These band positions indicate that Ef is close to mid-gap, and Efb is close to the equilibrium with the electrolyte enabling either cathodic or anodic band bending. We show an ability to control switching from n- to p-type behaviour through the application of external bias to the BiFeO3 thin film. This ability to control majority carrier dynamics at low applied bias opens a number of applications in novel optoelectronic switches, logic and energy conversion devices.
Original languageEnglish
Pages (from-to)5892-5897
Number of pages6
JournalMaterials Horizons
Volume10
Issue number12
DOIs
Publication statusPublished - 12 Oct 2023

Keywords

  • photochemistry ferroelectric bfo

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