Enhanced upconversion luminescence and temperature sensing performance in Er3+/Yb3+ -codoped K3ScF6 phosphors induced by tridoping with Bi3+ ions

Herein, K 3 ScF 6 upconversion luminescence (UCL) phosphors codoped with fixed Er 3+ , Yb 3+ and various Bi 3+ -concentrations were prepared by solid-state reaction method. Phase and structure analysis indicate that the prepared samples belong to a cubic system and exhibit the shift in peaks position due to Bi 3+ ions doping. The upconversion (UC) emission properties of K 3 ScF 6 :Er 3+ /Yb 3+ /Bi 3+ are investigated in detail. The UC emission intensity can be enhanced via tridoping with Bi 3+ ions under 980 nm laser diode (LD) excitation. Changes in Bi 3+ concentration and power density generate color tunability from green to red. Similarly, the CCT value changes from cool light to warm light. The fluorescence intensity ratio (FIR) technique based on Er 3+ thermal coupling level (TCLs) was used to study the temperature sensing performance, the relative sensitivity (S R ) of K 3 ScF 6 :0.05Er 3+ /0.15Yb 3+ /0.10Bi 3+ reaches a maximum of 0.0174 K -1 at 298 K. This indicates that K 3 ScF 6 :Er 3+ /Yb 3+ /Bi 3+ phosphors have potential applications in non-contact optical temperature sensors and color tunable devices. • K 3 ScF 6 :Er/Yb/Bi phosphors were synthesized by solid-phase reaction method. • When the introduction amount of Bi 3+ ions reaches 10 mol% mol, the upconversion luminescence intensity of the phosphor reaches the highest at 980 nm excitation. • Analysis of the phosphor's CIE diagrams reveals that green-to-red color tunability can be achieved in the yellow region. • The introduction of Bi 3+ greatly improves the temperature sensing performance of the K 3 ScF 6 :Er/Yb phosphor, indicating that the phosphor has good temperature sensitivity.