Impact of charge-compensated Fe and Nb co-substitution on BaTiO3: Bandgap and grain size reduction and enhanced bulk photovoltaic power of Al/BFNT/Ag solar cell

The generation of above bandgap photovoltage using bulk ferroelectric materials has become a subject of great interest, however, their photocurrent density is limited by a broad bandgap and poor conductivity. To overcome this limitation, we replaced aliovalent metal ions (Fe3+ and Nb5+) at the B-site of robust ferroelectric BaTiO3 and fabricated an Al/BaTi1-2xFexNbxO3/Ag photovoltaic device. Both the experimental and the theoretical studies showed that bandgap was lowered to similar to 2.55 eV and hence absorption of wide energy range of the solar spectrum was attained. An apt top electrode, reduced bandgap and domain size resulted in greater photocurrent density of 1.46 mu A/cm(2) and photovoltage of 8.31 V for Al/0.075BFNT/Ag solar cell in unpoled condition. This research suggest that reduced band gap, mixed structural phases and nano-sized domains suffices greatest PV power output while the large polarization and poling are not necessary prerequisites.