Effect of co-doping with Sm3+ on the emission of GdPO4:Dy3+ for white light-emitting diodes

A tunable white light emission based on Energy Transfer (ET) from Dy3+ to Sm3+ in GdPO4 has been obtained from a single nano-phosphor powders synthesized by combustion method. The single phosphor crystallises in the monoclinic system and presents agglomerated particles of nanometric size and needle like morphology. The interactions between Gd3+, Dy3+ and Sm3+ in GdPO4 have been discussed as a function of the excitation wavelength. An ET process from Dy3+ to Sm3+ was investigated based on the evolution of emission intensities and decay times as a function of the excitation wavelength. The quantum efficiency and the probability of ET are calculated. The white light color tones and correlated color temperature were tuned and a warm white was obtained due to ET and multicolor emission from both Dy3+ and Sm3+ ions. The proposed single phosphor was promising candidate for commercial lighting applications excited by blue or ultraviolet (UV) chips.