Bi3+/K+-Activated Calcium Lutetium Gallate and the Devices Under UV Chip for Warm WLED and Plant Lighting

Due to indoor agriculture development, blue light is necessary for plant lighting. Here, a blue phosphor, CaLuGaO4 (CLGO):xBi3+ (x = 0.005, 0.0075, 0.01, 0.02, 0.04), has been synthesized using a high-temperature solid-state method. The structure of CaLuGaO4 is orthorhombic, with a space group Pnma, and Bi3+ is doped into the host CaLuGaO4 to locate the Ca and Lu sites. Under 317 nm excitation, CLGO:Bi3+ exhibits a blue broadband emission from 340 to 600 nm. In addition, K+ ions are introduced to increase the emission by 1.6 times. Meanwhile, the thermal stability of CLGO:Bi3+ and CLGO:Bi3+,K+ is detected, with 72% of CLGO:Bi3+ to 75% for CLGO:Bi3+,K+. Most importantly, a is 66.11% quantum efficiency is achieved for CLGO:Bi3+,K+. A blue LED device is fabricated using CLGO:Bi3+,K+ combined with a 365 nm LED chip, whose blue light matches the absorption spectra of chlorophylls a and b. A warm WLED is also fabricated using the commercial red phosphor CaAlSiN3:Eu2+, the green phosphor (Ba, Sr)2SiO4:Eu2+, and the blue phosphor CLGO:0.01 Bi3+,0.04K+ with the CCT of 4679 K and an Ra of 87. All these results indicate that the blue phosphor CLGO:Bi3+,K+ is an excellent candidate for plant lighting and warm WLED.