Two-Step Synthesis and Surface Modification of CaZnOS:Mn 2+ Phosphors and the Fabrication of a Luminescent Poly(dimethylsiloxane) Film.

The CaZnOS:Mn2+ (CZOSM) phosphor has been extensively studied for its excellent optical performance, with a typical red emission band peaking at about 580 nm ascribed to the 4 T1 (4 G)-6 A1 (6 S) transition of Mn2+ . Herein the CZOSM phosphor was synthesized by a novel two-step method accompanied by control of the morphology of the precursor in the first step followed by sintering in the second step, which demonstrated improved emission intensity and uniform morphology simultaneously compared to those obtained by the traditional solid-state reaction route. Thus, uniform ZnS:Mn2+ particles could be obtained by a hydrothermal method, and then a Ca(OH)2 shell was coated onto the ZnS:Mn2+ particles via a precipitation reaction. After that, these mixtures were sintered at the optimum temperature 800 °C in an argon atmosphere to prepare the CZOSM particles. Oleic acid (OA) was further used to transfer the hydrophilic CZOSM phosphors to hydrophobic ones. Finally, luminescent poly(dimethylsiloxane) (PDMS) films were fabricated by using the hydrophobic CZOSM@OA powders, and their optical performance and flexibility were evaluated. Our results provide insight into the synthesis of hydrophobic phosphor particles used in luminescent PDMS films and help to unravel their potential application for flexible optical devices.