Enhanced photovoltaic properties in polycrystalline BiFeO3 thin films with rhombohedral perovskite structure deposited on fluorine doped tin oxide substrates

Polycrystalline BiFeO3 thin films have been deposited on fluorine doped tin oxide substrates successfully through a modified chemical solution deposition process based on using N,N-dimethylformamide as solvent. Structural analyses show that, N,N-dimethylformamide is beneficial to reduce the structural strain, and hence rhombohedral BiFeO3 films rather than the conventional pseudocubic ones were obtained. Absorption spectrum indicates that the modified process derived rohombohedral BiFeO3 has a narrower band gap (2.54 eV) than that of the conventional process derived pseudocubic BiFeO3 (2.76 eV). The BiFeO3 shows good photovoltaic properties with indium tin oxide as top electrode. The short circuit current density and open circuit voltage of the heterojunctions are measured to be 0.13 mA/cm(2) and 0.65 V. respectively, much higher than the reported values for the conventional process derived pseudocubic BiFeO3 based heterojunctions. Our results indicate that the modified process derived rhombohedral BiFeO3 can induce higher photovoltaic effect compared with the conventional process derived pseudocubic counterpart. (C) 2012 Elsevier B.V. All rights reserved.