In-situ stress modulated ferroelectric photovoltaic effect in cluster-assembled TbFe2/Bi5Ti3FeO15 heterostructural films

Abstract

TbFe2/Bi5Ti3FeO15 heterostructural films were prepared by inserting cluster-assembled TbFe2 microdiscs into a Bi5Ti3FeO15 matrix using low energy cluster beam deposition combined with sol-gel methods. The phase structure, ferroelectric properties, bandgap, photovoltaic spectral response, and performances of the ferroelectric photovoltaic effect were modulated by the in situ stress driven by magnetostriction of TbFe2 clusters under external magnetic fields. The short-circuit current, open-circuit voltage, and power conversation efficient increase with the in situ stress, reaching 0.026 mA/cm2, 9.5 V, and 5.88 × 10-2%, respectively, under a maximum in-stress of 0.075 GPa. So the high open-circuit voltage above bandgap is attributed to the distinct bandgap shifting and the effective separation of photogenerated electron-hole pairs derived from the in situ stress induced large built-in field. The in situ stress dominated symmetry breaking contributes to the improvement of the power conversation coefficient. The in situ dynamic internal stress provides a high efficient approach to modulate and improve ferroelectric photovoltaic effects.