Visible Ni2+ upconversion luminescence in Ni2+, Yb3+ co-doped CsCdBr3

Excitation around 10 200 and 10 600 cm−1 into the absorption peaks of Yb3+ leads to visible Ni2+ 1T2g → 3A2g upconversion luminescence in the doubly doped CsCdBr3: Ni2+, Yb3+ at cryogenic temperatures. The excitation spectrum indicates that an Yb3+ absorption step is involved in the upconversion process leading to visible Ni2+ luminescence. This process via Yb3+ excitation is more efficient than the upconversion mechanism involving only Ni2+, which is observed in the title compound for excitation energies above 11 200 cm−1. Upconversion lifetimes point towards an energy transfer upconversion mechanism for the Ni2+/Yb3+ system in CsCdBr3.