Tunable white light photoluminescence of a single phase Tm3+/Tb3+/Eu3+ codoped GdPO4 phosphor

The present study describes the production of triply-doped GdPO4 and its optical characteristics. Structural in-formation of the prepared material has been investigated by using X-ray diffraction and Fourier transform infrared spectroscopy. The material synthesized crystallizes into a single monoclinic crystal of space group P 21/ n. The excitation curves of photoluminescence of single doped GdPO4: Tm3+, Tb3+, and Eu3+ are recorded and their emission spectra are analyzed. Triple-doped material emits multi colour light after a single UV stimulation. White light emission was seen in both triply-doped GdPO4 with variable Tm3+ concentration and triply-doped GdPO4 with variable Eu3+ concentration. GdPO4 doped with Tb3+ (7 mol%), Tm3+ (1.5 mol%), and Eu3+ (2 mol%) has colour coordinates (x = 0.3290, y = 0.3291) approximately near the value of typical white colour coordinates (x = 0.333, y = 0.3333). Furthermore, the transfer of energy in Tm3+, Tb3+ and Eu3+ in triple doped phosphor with varying Eu3+ concentrations was explained. Electric dipole-dipole interaction is used to justify and describe the process of energy transfer from Tb3+ to Eu3+. Decay time measurements were performed to explain energy transfer. Colour rendering index (CRI), Corelated colour temperature (CCT), Quantum efficiency and thermal stability of the prepared phosphor was calculated. All these parameters infer that GdPO4 doped with Tm3+, Tb3+ and Eu3+ may have potential application in white LEDs.