Cooperative energy acceptor of three Yb3+ ions

Abstract

Our previous work first reported the cooperative sensitized luminescence from Cu2+ or Pb2+ by three clustered Yb3+ ions, in which three NIR photons can be converted into a high energy photon. Could a reverse process happen that a high energy photon is cut into three NIR photons? This work demonstrated an example of three-photon quantum cutting (QC) phosphor, CaF2:Ce3+,Yb3+, in which three clustered Yb3+ ions (Yb3+-trimer) cooperatively and indirectly received a 306 nm ultraviolet (UV) photon energy transferred from a Ce3+ ion in 5d excited state and emitted three 975 nm near-infrared (NIR) photons. The cluster destruction experiments were designed to verify the necessity of the presence of Yb3+-trimers for QC. The dynamical analysis on luminescence of Ce3+ ions confirmed the energy transfer from Ce3+ ions to Yb3+-trimers. The doping concentration effect on luminescence was investigated. Furthermore, the maximum energy transfer (ET) efficiency and the corresponding QC efficiency were estimated to be 61% and 222%, respectively. Therefore, the reported three-photon QC phosphor has an attractive prospect in efficiently harvesting solar energy for silicon solar cells.