Polarization-Induced Photovoltaic Effects in Nd-Doped BiFeO₃ Ferroelectric Thin Films

Nd-doped BiFeO₃ (BNF) thin films were fabricated on SrRuO₃ (SRO)-coated (100) Nb-doped SrTiO₃ substrates by pulsed laser deposition, and nondoped BiFeO₃ (BFO) thin films were also fabricated similarly for comparison. Then, Nd-doping effects on ferroelectric and photovoltaic properties were evaluated. Polarization-induced photovoltaic effects were observed in both the BFO and BNF solar cell structures with top and bottom electrodes under intense laser illumination. Using Au top electrodes, enhanced photovoltaic properties were observed in the BNF cell compared with the BFO cell. To improve the photovoltaic properties of the BNF cell, instead of the Au top electrodes, In–Sn–O (ITO) top electrodes were employed for the BNF cell. As a result, the photovoltaic properties were found to be markedly improved, resulting in an open circuit voltage of 0.81 V and a short circuit current density of 12.1 mA/cm².