365 nm UV light excitable broadband cyan-blue emitting KSrScSi2O7: xCe3+ phosphor and its application in high color rendering pc-WLED

Phosphor-converted white light-emitting diode (pc-WLED) is crucial for solid-state lighting, but the color rendering index of commercial pc-WLED needs to be improved. In this study, a series of silicates KSrScSi 2 O 7 : x Ce 3+ ( x= 0-10at%) were synthesized. Under the 365 nm near-ultraviolet excitation, the silicate emits a high-quality broadband cyan-blue light (385-550 nm) covering the cyan gap. The emission intensity reaches its maximum at approximately 450 nm and the emission peak is slightly shifted with varying Ce 3+ concentration, which is because Ce 3+ doping changes the crystal field around the luminescence center. The prepared phosphors showed promising properties for application in high-color rendering lighting. The crystal structure analysis via X-ray diffraction and Rietveld refinement and Gaussian fitting of the PL spectra indicated that Ce 3+ occupies the Sr 2+ and K + positions in the monoclinic host lattice. The optimal Ce 3+ content is 3at% and concentration quenching is attributed to the non-radiative energy transfer between the nearest-neighboring Ce 3+ ions. The temperature-dependent luminescence showed that the T 50 is 394 K for the KSrScSi 2 O 7 : x Ce 3+ materials. The thermal quenching is attributed to increased lattice vibrations and enhanced non-radiative transitions at elevated temperatures. The performance of the pc-WLED device fabricated with KSrScSi 2 O 7 : 3at%Ce 3+ was studied, and the device showed a high-color rendering index (Ra=93.8) and exceptional stability during operation.