Optimization of cerium doped garnets using combinatorial chemistry for application as luminescent conversion phosphors in white LEDs

摘要

An area of considerable research interest is the development of visible light, downconversion phosphors for application in white light emitting diodes (LEDs). In such devices, a blue LED can act as the primary light source, excitingphotoluminescence in a phosphor with subsequent broad band emission occurring at visible wavelengths of lower energy. A combinatorial approach to synthesize and screen potential inorganic phosphors for such an application has been developed. Usingsolution chemistry techniques, solid state thin film arrays of (Y{sub}(1-x)Gd{sub}x){sub}(3-x)(Al{sub}(1-y)Ga{sub}y){sub}5O{sub}12:(Ce{sup}3+){sub}z, where x and y range from 0 to 1.0 and z is equal to 0.03 were synthesized. Subsequent characterizationdemonstrates that the combinatorial approach can be used to rapidly screen potential phosphors for use as luminescence down-converters in white LEDs. Emission and excitation trends match those reported in the literature for traditionally prepared powdersamples. The optimal Ce{sup}(3+) concentration in Y{sub}3Al{sub}5O{sub}12 (YAG) was identified as approximately 1.5 mol%, and within the YAG-substituted host specific compositions were identified as promising blue to yellow phosphor candidates.