High color rendering index single phase white light emitting phosphors based on Tb3+/Sm3+ co-doped CePO4 nanocrystals: the role of Tb3+ as a bridge between Ce3+ and Sm3+

Abstract

Single phase white light emitting CePO₄ nanocrystals doped with Tb³⁺ and Sm³⁺ were synthesized through a sol gel route for the first time. The single phase monoclinic structure of the samples was confirmed by XRD analysis. FTIR and XPS analysis were used to demonstrate that CePO₄ is a good host with a minimum quenching environment. The triple energy transfer processes from Ce³⁺ to Tb³⁺, Ce³⁺ to Sm³⁺ and Ce³⁺ to Sm³⁺via Tb³⁺ in CePO₄ nanocrystals are analyzed by photoluminescence excitation and emission spectra. The role of Tb³⁺ as a bridge between Ce³⁺ and Sm³⁺ ions in CePO₄ is systematically studied by varying the concentrations of Tb³⁺ and Sm³⁺. The existence of energy transfer channels from Tb³⁺ to Sm³⁺ from ⁵D₃ and ⁵D₄ energy levels of Tb³⁺ is revealed by decay analysis. The CIE chromaticity coordinates, color temperature and high color rendering index suggest that the newly developed cool white light emitting Tb³⁺ and Sm³⁺ co doped CePO₄ nanocrystals are a potential candidate in the field of white light applications.