Blue shift in band gap and photoluminescence of pulsed laser deposited SrS:Ce/quartz thin film nanophosphors

We report on the synthesis of single phase SrS:Ce/quartz thin film nanophosphors at a substrate temperature of 400 °C using pulsed laser deposition. The AFM and FESEM micrographs reveal the island structure with granular growth of nanophosphors. The average crystallite size (∼ 13 nm using Williamson-Hall plot), the average grain size (∼ 40 nm using AFM) and the blue shift in band gap confirm the nanostructure formation. Interestingly, the photoluminescence emission corresponding to 5d−4f transitions in Ce3+ ion under the cubic crystal field of SrS also exhibits a significant blue shift, which can be explained using phenomenological crystal field model modified by covalency factor.