Luminescence properties of Ca1−xSrxSe:Ce phosphors and their potential application for GaN-based LEDs

A series of solid solution phosphors Ca1−xSrxSe:0.02Ce3+ were prepared using high-temperature solid-state reaction technique. Their diffuse reflectance and luminescent spectra at room temperature were investigated and discussed. The optical band gap Eg energies of CaSe and SrSe were derived. Because of its broad band absorption in the range of 400-500 nm, Ca1−xSrxSe:Ce3+ can suit the application requirements for GaN-based light-emitting diodes (LEDs). The emission wavelength and the coordinates systematic shift from yellowish green to bluish green with an increase in x of Ca1−xSrxSe:Ce3+. Using Dorenbos's empirical equation, the values of energies of the lowest f-d transition absorption E, redshift D and Stokes shift ΔS for Eu2+ in the same host were predicted. The results were in good agreement with the experimental data.