Photovoltaic Effect of Epitaxial ferroelastic BiVO₄ Film

Pao-Wen Shao^1*, Ying-Hao Chu¹

¹Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan

* Presenter:Pao-Wen Shao, email:crag418@gmail.com

Bismuth vanadate (BiVO₄) is an attractive candidate for photovoltaic material due to high absorption in visible light region. However, pristine BiVO4 without any modification usually exhibits an inefficient separation of photo-excited electron-hole pairs and therefore results in low photocatalytic efficiency. In this work, for centrosymmetric crystal BVO, it is reported that ferroelasticity only exists on bulk surface due to the broken symmetry. In order to investigate the nature of ferroelasticity in epitaxial thin film, we demonstrated ferroelastic BVO thin film by pulse laser deposition for the first time in the world. With YSZ substrate confinement, phase transformation leads to twin domains that partially compensate the transformation strain during cooling. It produces twin domains and these twin domains shows localized piezoresponse. We also rely on piezoresponse force microscopy (PFM) to investigate twin domain polarization directions. On the other hand, we supposed the spontaneous in-plane electric field would therefore promote separation of electron-hole pairs to improve the photocatalytic performances.

Keywords: Ferroelasticity, BiVO₄, Epitaxial, thin film, Piezoresponse force microscopy