Boosting the Photocurrent in BiFeO3 Thin Films via a Domain-Wall-Defect Interaction

Ferroelectric domain walls are of great interest due to their nontrivial electronic properties. Herein, a large photocurrent is detected only in the stripe domain structure of BiFeO3 thin films. By the temperature-resolved time-dependent photocurrent measurements, the significant trapping effect is revealed to be associated with the abnormal photocurrent. Further optoelectronic measurements with the defect density tuned unveiled that the interaction between the defects and domain walls is essential to give a rise to a large photocurrent in BiFeO3 thin films. The study reveals a novel domain-wall-defect photovoltaic effect and provides a simple thermal annealing-treatment strategy to boost the photocurrents and power output by several folds.