Origin of Spectral Blue Shift of Lu(3+)-Codoped YAG:Ce(3+) Phosphor: First-Principles Study

[Image: see text] Lu(3+), with the smallest ionic radii in lanthanide ions, is an important and beneficial cation for tuning spectrum shifting toward a longer wavelength by ion substitution in many phosphors for solid-state lighting. However, in the Lu(3+)-substituted garnet system, the phosphor always has smaller lattice parameters and exhibits a shorter emission wavelength than other garnet phosphors. The mechanism of such a spectral blue shift induced by the Lu(3+)-codoped garnet phosphor is still unclear. In this study, the local and electronic structures of Lu(3+)-codoped and Lu(3+)-undoped YAG:Ce(3+) phosphor have been studied by first-principles calculation to reveal the origin of the spectral blue shift. Our results provide a full explanation of the experimental data and the methodology, which is useful to understand and design garnet phosphors with tunable emission characteristics.