Quantum Cutting in KGd(CO):Tb Green Phosphor.

Phosphors with a longer excitation wavelength exhibit higher energy conversion efficiency. Herein, quantum cutting KGd(CO):Tb phosphors excited by middle-wave ultraviolet were synthesized via a hydrothermal method. All the KGd(CO):Tb phosphors remain in monoclinic structures in a large Tb doping range. In the KGd(CO) host, D and I of Gd were employed for quantum cutting in sensitizing levels. The excited state electrons could easily transfer from Gd to Tb with high efficiency. There are three efficient excited bands for quantum cutting. The excited wavelengths of 244, 273, and 283 nm correspond to the transition processes of S→D (Gd), S→I (Gd), and F→F (Tb), and the maximum quantum yields of KGd(CO):Tb can reach 163.5, 119, and 143%, respectively. The continuous and efficient excitation band of 273-283 nm can well match the commercial 275 nm LED chip to expand the usage of solid-state light sources. Meanwhile, the phosphor also shows good excitation efficiency at 365 nm in a high Tb doping concentration. Therefore, KGd(CO):Tb is an efficient green-emitting phosphor for ultraviolet-excited solid-state light sources.