Ferroelectric polarization enhancement of photovoltaic effects in BaTiO3/BiFeO3/TiO2 heterostructure by introducing double-functional layers

Abstract

Multilayer Pt/BaTiO3/BiFeO3/TiO2 heterostructure was fabricated on FTO substrates by sol-gel technique. This heterostructure shows strong light absorption, sensitive optical switching response, and excellent photovoltaic properties, which are effectively modulated by the ferroelectric polarization. The short circuit current density and open circuit voltage of the multilayer heterostructure are significantly enhanced compared with that of the single layer BiFeO3 thin film under the initial and positive polarization states. Analysis on the schematic energy band diagrams suggests that the excellent photovoltaic properties can be attributed to the interface Schottky barrier regulated by ferroelectric polarization, in which the TiO2 layer acts as the electron collection layer, and the ferroelectric BaTiO3 layer acts as a hole collection layer and also an auxiliary photovoltaic absorption layer to enhance optical absorption properties, thus improve the light absorption efficiency and the separation of electron-hole pairs. These results provide a promising method to optimize the performance of ferroelectric photovoltaic devices by using multilayer heterostructure.