Advances in the Development of Quantum Splitting Phosphors

Quantum splitting phosphors (QSPs) are phosphors that could convert VUV radiation into more than one visible photon. These phosphors have the potential to improve the efficacy of current Hg fluorescent lamps and/or Xe lamps by reducing the Stokes shift energy loss after VUV excitation (λexc=185 nm for Hg lamps or 147 nm and 172 nm for Xe lamps provided the emission color of the phosphor matches the eye sensitivity. The current technology in QSPs and their potential limitations will be discussed in this paper. At GE-CRD, we have discovered and developed QSPs that meet the requirements for use in current Hg based fluorescent lamps. The steady state and time resolved optical properties of one of these phosphors, SrAl12O19:Pr3+,Mg2+, has been measured to estimate the maximum quantum efficiency and onset of concentration quenching in this phosphor. The maximum quantum efficiency for SrAl12O19:Pr3+,Mg2+ has been calculated to be ∼125-135% for 185 nm excitation with an upper bound on the Pr3+ doping level of ∼1%.