Flexible and luminescent polymer nanocomposite films (YPO4:Pr3+/ polystyrene): Investigation of structural, morphological and photoluminescence properties for solid-state lighting applications

Luminescent polymer films are promising for future optoelectronic devices owing to their ease of synthesis, tunable properties and flexibility. The present work reports on the fabrication of YPO4:Pr3+/polystyrene based flexible and luminescent nanocomposite (NC) films followed by an investigation of their structural, morphological and photoluminescence properties for their potential applications in optical devices. NC films were successfully prepared by direct solution mixing of YPO4: Pr3+ (0.1, 2 at. %) luminescent nanoparticles (NPs) and polystyrene (PS). X-ray diffraction (XRD) analysis of NC films revealed an improvement in crystallinity upon increasing YPO4: Pr3 NPs doping into PS films. The emission spectra of the pure and YPO4:Pr3+/PS NC films under UV excitation at 223 nm showed the same features with a broad emission band in the 280–400 nm region. However, an increase in emission intensity, and absence of interconfigurational emission characteristic of the YPO4: Pr3+ NPs were observed in UV region, due to the strong absorption band of PS in this region. Upon doping, YPO4:Pr3+ NPs were found to reduce their intrinsic luminescence emission from interconfigurational transitions of Pr3+ ions. However, it was dominated by an orange-red luminescence of 1D2→3H4 transition, while, no emission was observed for the PS film owing to its transparency in the visible region. The fluorescence decay times of 1D2→3H4 in the NC films were shorter as compared to those of the original NPs. Chromatic coordinates and correlated color temperature indicated that the YPO4:Pr3+/PS NC films are promising polymer-phosphors for lighting applications.