Multifactorial coupling to greatly enhance photocurrent density of BiFeO₃-based ferroelectric photovoltaic architectures

The ferroelectric photovoltaic effect in BiFeO₃ has attracted much attention recently. However, the potential of BiFeO₃ as a photovoltaic material is limited due to its low photocurrent density and consequently low power conversion efficiency. Herein, a novel ferroelectric photovoltaic architecture based on the (Pr, Ni) gradient-doped BiFeO₃-based thin film coupled with Au nanoparticles layer has been designed and fabricated. The experimental results and analysis show that this photovoltaic architecture exhibits extremely large photocurrent density (5.19 mA/cm²), which is about 472 times larger than that of pure BiFeO₃ film (11 μA/cm²) and about 10 times larger than that of the conventional (Pr, Ni)-doped BiFeO₃ film (0.54 mA/cm²). The enhanced photocurrent density should be attributed to the multifactorial coupling effect in this photovoltaic architecture, including the built-in electric field formed by the gradient distribution of oxygen vacancies, the flexoelectric effect and Local Surface Plasmon Resonance effect of Au nanoparticles.