NIR light guided enhanced photoluminescence and temperature sensing in Ho(3+)/Yb(3+)/Bi(3+) co-doped ZnGa(2)O(4) phosphor

The conversion of NIR light into visible light has been studied in Ho(3+)/Yb(3+)/Bi(3+) co-doped ZnGa(2)O(4) phosphor for the first time. The crystallinity and particles size of the phosphor increase through Bi(3+) doping. The absorption characteristics of Ho(3+), Yb(3+) and Bi(3+) ions are identified by the UV–vis-NIR measurements. The Ho(3+) doped phosphor produces intense green upconversion (UC) emission under 980 nm excitations. The emission intensity ~ excitation power density plots show contribution of two photons for the UC emissions. The UC intensity of green emission is weak in the Ho(3+) doped phosphor, which enhances upto 128 and 228 times through co-doping of Yb(3+) and Yb(3+)/Bi(3+) ions, respectively. The relative and absolute temperature sensing sensitivities of Ho(3+)/Yb(3+)/5Bi(3+) co-doped ZnGa(2)O(4) phosphor are calculated to be 13.6 × 10(−4) and 14.3 × 10(−4) K(−1), respectively. The variation in concentration of Bi(3+) ion and power density produces excellent color tunability from green to red via yellow regions. The CCT also varies with concentration of Bi(3+) ion and power density from cool to warm light. The color purity of phosphor is achieved to 98.6% through Bi(3+) doping. Therefore, the Ho(3+)/Yb(3+)/Bi(3+):ZnGa(2)O(4) phosphors can be suitable for UC-based color tunable devices, green light emitting diodes and temperature sensing.