Photovoltaic effect of a bilayer film with Bi4Ti3O12/BiFeO3 heterostructure

Bi4Ti3O12/BiFeO3 (BTO/BFO) heterostructure bilayer film is prepared on fluorine-doped tin oxide conductive glass by a sol–gel process. The X-ray diffraction result shows that no additional phase can be found besides the characteristic diffraction peaks of BTO and BFO. Piezoelectric force microscopy measurement confirms the complete domain switching and local ferroelectric nature. The open circuit voltage and short circuit current density of the bilayer film are measured to be about 0.38V and −56.24µAcm−2, respectively, higher than those of the BTO. The BTO/BFO film exhibits repeatable and stable instantaneous response of photocurrent. A theoretical band diagram model combining p–n heterostructure with ferroelectric polarization is constructed to describe the mechanism of photovoltaic enhancement of the film. •Bi4Ti3O12/BiFeO3 bilayer film was deposited on FTO substrate by a sol–gel technique.•An obviously improved photovoltaic response for the bilayer film was observed.•Time dependence of the zero bias photocurrent density indicates a repeatable photocurrent.•A model combined p–n heterostructure with ferroelectric polarization was proposed.