Ce3+-Sensitized GdPO4:Tb3+ Nanorods: An Investigation on Energy Transfer, Luminescence Switching, and Quantum Yield

Herein we report the enhanced green emission from Tb3+-doped GdPO4 nanorods sensitized with Ce3+. The increase in the rate of nonradiative transition processes in sensitizer due to efficient energy transfer to activator is realized from steady-state and dynamic luminescence studies. Luminescence quenching due to cross relaxation is least significant up to 20 at. % Ce3+ and 7 at. % Tb3+ concentration. The quantum yield of the sample with maximum luminescence, i.e., GdPO4:Tb3+ (5 at. %)/Ce3+ (7 at. %), is found to be 28%. Also, samples are readily redispersible in water and could be easily incorporated in polymer-based films that show strong green light emission under UV excitation. The luminescence switching (ON and OFF) behavior is examined using alternately an oxidizing agent (KMnO4) and then a reducing agent (ascorbic acid) through a redox reaction (Ce3+/Ce4+). Both GdPO4:Tb3+ and GdPO4:Tb3+/Ce3+ are observed to be paramagnetic.