Broadband UV excitable near-infrared downconversion luminescence in Eu2+/Yb3+:CaF2 nanocrystals embedded glass ceramics

Cooperative downconversion was realized in glass ceramics containing Eu2+/Yb3+:CaF2 nanocrystals with Eu2+ greatly absorbing ultraviolet photons. Upon excitation of Eu2+ ions to the 5d level with an ultraviolet photon at 320 nm, emission of two near infrared photons at 976 nm of Yb3+ were achieved. The dependence of the visible and near-infrared emissions, decay lifetime, and quantum efficiency on the Yb3+ doping content has been investigated. The maximum energy transfer efficiency and the corresponding downconversion quantum efficiency were estimated to be 51% and 151%, respectively.

Research highlights▶ Eu2+/Yb3+:CaF2 nanocrystals embedded transparent glass ceramics are prepared. ▶ Yb3+ downconversion emission occurs through energy transfer from Eu2+ to Yb3+. ▶ Such material might be used to enhance the energy efficiency of Si solar cell.