Enhanced luminescence performance of CaO: Ce3+, L-i+, F- phosphor and its phosphor-inglass based high-power warm LED properties

Deng, Jiankun; Zhang, Haoran; Zhang, Xuejie; Molokeev, Maxim S.; Qiu, Jianbei; Liu, Yingliang; Lei, Bingfu; Ma, Li; Wang, Xiaojun JOURNAL OF MATERIALS CHEMISTRY C, 6 (15):4077-4086; 10.1039/c8tc00813b APR 21 2018

To obtain white light-emitted diodes (wLEDs) with a low correlated color temperature (CCT) and a high color rendering index (CRI), red-emission is indispensable in their emission spectra. Herein, CaO:Ce3+,Li+,F yellow phosphors with more red spectral component have been prepared via a high temperature solid-state reaction. As compared to the F undoped samples, CaO:Ce3+,Li+,F phosphor have lower critical doping concentration of Ce3+ and show stronger luminescence. At the critical concentration, a quantum efficiency of 66.4% and enhanced thermal and chemical stability were obtained in CaO:Ce3+,Li+,F. Furthermore, a CaO:Ce3+,Li+,F-based phosphor-in-glass (PiG) using the red-emitting glass system with the composition of SiO2–Na2CO3–Al2O3–CaO:Eu3+ as the host material was constructed and used for high-power white LED applications. Such PiG samples with different phosphor doping concentrations can satisfy various light color demands and display higher reliability than the CaO:Ce3+,Li+,F phosphor. An optimal PiG-based wLED exhibits color coordinates of (0.3769, 0.3386), a CCT of 3774 K, a CRI of 82.5 and a LE of 73.1 when the mass ratio of phosphor to glass matrix was 7 : 50 in PiG. Moreover, such PiG-based wLED also showed acceptable color stability under different drive currents. All the above results demonstrate that CaO:Ce3+,Li+,F can be expected to be a potential alternative yellow phosphor for blue light excited PiG based warm wLEDs, particularly for high-power devices.