Synthesis and optical studies of KCaVO4:Sm3+/PMMA nanocomposites

Abstract

Polymer nanocomposite (PNC) films (∼100 μm in thickness) with different weight percents (0–12 wt %) of KCaVO4:Sm3+ phosphor in polymer (PMMA) have been synthesized using solution casting methods. The presented work reports the optical property measurements of such films in order to investigate their suitability for use in flexible display devices. X-ray diffraction analyses were employed to obtain the structural parameters such as crystallinity, shape and particle-size distribution (of phosphors) in the obtained PNCs. XRD data of the PNCs confirmed the average crystalline size of the embedded phosphors in the range of 40–50 nm. The emission and excitation spectra were obtained using photoluminescence spectroscopy to quantify the spectral attributes of the fluorescent PNC films. The emission bands were observed at 568, 600, 646 and 704 nm corresponding to the characteristic transitions of Sm3+ when excited at 401 nm. The chromaticity coordinates (x = 0.60, y = 0.39) of the polymer nanocomposite (PNC) films validated orange red (amber) color in the CIE diagram. The diffuse reflectance (DR) studies were carried out using a UV-Vis spectrophotometer to obtain the optical band gaps (Eg) and were generally estimated to lie in the range of 3–3.5 eV for different PNCs (with varying weight percents of the phosphor). Differential scanning calorimetry (DSC) was exploited to account for the different thermal properties of the PNC films such as thermal stability, glass transition temperature and degree of crystallinity, etc. With the addition of phosphor an increase in the thermal stability of the PNC films was observed as compared to the pure PMMA.