Tunable color emitting of CaAl2Si2O8: Eu, Tb phosphors for light emitting diodes based on energy transfer

A series of single-phased CaAl2Si2O8: Eu, Tb phosphors have been synthesized at 1400 °C via a solid state reaction. The emission bands of Eu2+ and Eu3+ were observed in the air-sintered CaAl2Si2O8: Eu phosphor due to the self-reduction effect. Tb3+ ions that typically generated green emission were added in CaAl2Si2O8: Eu phosphor for contributing for a wider-range tunable emission. Energy transfer from Eu2+ to Tb3+ and the modulation of valence distribution of Eu2+/Eu3+ that contributes to the tunable color emitting were elucidated. More importantly, a white emission can be obtained by controlling the codoped contents of Li+ as well as suppressing the self-reduction degree of Eu. The white light emitting with the color coordinate (0.326, 0.261) was obtained, which indicates that CaAl2Si2O8: Eu, Tb is a promising tunable color phosphor for application in ultraviolet light emitting diodes (UV-LEDs).