Impact of Ferroelectric Domain Structure on Bulk Photovoltaic Effect of Epitaxial BiFe1−xCoxO3 Films

Abstract Ferroelectric domain is an elusive feature on bulk photovoltaic effect and can be tuned by the growth conditions. Here, in (111)‐oriented BiFe 1− x Co x O 3 epitaxial films, the periodic ferroelectric domains structure is manipulated by Co‐doped concentration. The intrinsic 109° domain structure is turned into 71° domain structure due to reduction of crystal cell volume. The experimental results show that ferroelectric domain and ferroelectric domain wall (DW) play completely different roles in bulk photovoltaic effect. In ferroelectric domain structure, the domain provides a depolarization field for the separation of photogenerated carriers and DW is carriers transport channel. The 71° ferroelectric domain creates a larger depolarization field than the 109° domain, which leads to open‐circuit voltage exceeding 1.7 V. Besides, the 71° domain wall has a higher photoconductivity than the 109° domain wall, which makes short‐circuit current density reaching 0.42 mA cm −2 . The optimization of domain structure will effectively enhance bulk photovoltaic effect and also provides a new method to regulate the domain structure for bulk photovoltaic devices.