Color-tunable upconversion luminescence and prolonged Eu3+ fluorescence lifetime in fluoride KCdF3:Yb3+,Mn2+,Eu3+via controllable and efficient energy transfer

Intense Eu³⁺ upconversion emission is realized in KCdF₃:Yb³⁺,Mn²⁺,Eu³⁺via controllable and efficient unidirectional energy transfer from Yb³⁺-Mn²⁺ dimers. Moreover, significantly prolonged Eu³⁺ UC emission lifetime is observed in this system.