Achievement of high-efficiency sunlight-like emission in Rb2CaP2O7: Ce3+, Eu2+ phosphors

High quantum efficiency and thermal stability have always been the goals to pursue and challenges for lighting application. In this work, sunlight-like white emission has been achieved in a new prepared single phased Rb2CaP2O7: 0.005Ce3+, 0.01Eu2+ phosphor, which exhibits high internal quantum efficiency (IQE = 74.36%), external (EQE = 56.77%) quantum efficiency and excellent thermal stability. Based on the broadband emission from 4f-5d transitions of Ce3+/Eu2+ ions and high energy transfer efficiency of Ce3+→Eu2+ (measured up to 60%), the extremely wide color-tunable emission from blue-violet to white and then to orange-yellow is realized in Rb2CaP2O7: 0.005Ce3+, xEu2+ phosphors. Moreover, a prototype WLED device is packaged by combing the prepared Ra2CaP2O7: 0.005Ce3+, 0.01Eu2+ white phosphors with an UV LED chip (λ = 310 nm), and the obtained WLED emits bright sunlight-like white light with color coordinates of (0.377, 0.324). The correlated color temperature (CCT) and the color rendering index (CRI) value of the WLED are 3208 K and 88.4, respectively. These results can provide effective guidance for the design of color-tunable single-phase white phosphors with high luminous efficacy and thermal stability.