Changing Ce Content and Codoping Mn Induced Tunable Emission and Energy Transfer in CaSrAlO:Ce,Mn.

A series of color-tunable Ce single-doped and Ce, Mn codoped CaSrAlO phosphors were synthesized by a high-temperature solid-state reaction. The crystal structure, luminescent properties, and energy transfer were studied. For CaSrAlO:Ce phosphors obtained with Al(OH) as the raw material, three emission profiles were observed. The peak of photoluminescence (PL) spectra excited at ∼360 nm shifts from 470 to 420 nm, while that of the PL spectra excited at 305 nm stays unchanged at 470 nm with the increase of Ce content. Furthermore, the peak of PL spectra is situated at 500 nm under excitation at ∼400 nm. The relationship between the luminescent properties and crystal structure was studied in detail. Ce, Mn codoped CaSrAlO phosphors also showed interesting luminescent properties when focused on the PL spectra excited at 365 nm. Obvious different decreasing trends of blue and cyan emission components were observed in CaSrAlO:0.11Ce,xMn phosphors with the increase in Mn content, suggesting different energy transfer efficiencies from blue- and cyan-emitting Ce to Mn. Phosphors with high color-rendering index (CRI) values are realized by adjusting the doping content of both Ce and Mn. Studies suggest that the CaSrAlO:Ce,Mn phosphor is a promising candidate for near UV-excited w-LEDs.