<title>Combinatorial synthesis and screening of Cerium-doped garnet phosphors for application in white GaN-based LEDs</title>

Abstract

ABSTRACT A combinatorial approach has been used to generate solid state thin-film of different garnet structures (A 1-x ,B x ) 3-z (C 1-y ,D y ) 5 O 12 :Ce 3+z (called libraries), where A, B = Y, Gd, Lu, La; C, D = Al, Ga, Sc; x and y = 0 to 1.0; and z = 0.03. X-raydiffraction was used to select library samples of the crystalline garnet phase. Combinatorial chemistry methods were used asa tool to rapidly synthesize and screen potential inorganic phosphors for use as blue to yellow conversion phosphors in whiteLEDs. Libraries of these various garnets were then characterized spectroscopically. Emission and excitation trends arereported for various libraries and were found to reproduce previous trends in literature. Lattice constants, chromaticity, andPL intensity are also examined as a function of the different compositions. Emission and excitation trends reveal that aslarger cations are substituted for the Y (dodecahedral) site in YAG, emission and excitation are red-shifted and as largercations are substituted for the Al (octahedral and tetrahedral) site, emission and excitation are blue-shifted. If smaller ion s aresubstituted for those respective sites an opposite trend is observed.Keywords: White LEDs, garnet, cerium, YAG, luminescence, combinatorial chemistry