Flexible alizarin red/PVA composites with colossal dielectric and high power laser filtering properties

Abstract

Dye/polymer composite is gradually emerging as an indispensable component of the modern optoelectronics technology due to their fascinating optical, mechanical and electrical properties. Here, we investigate the structural, mechanical, optical and electrical properties of the economical, self-standing, flexible alizarin red (AR)/poly (vinyl alcohol) (PVA) composites (AR concentration 0 wt %, 0.1 wt %, 1.0 wt %, 2.0 wt %) prepared by facile solution casting technique. The UV–Vis absorption spectroscopy results in higher absorption of the composites with increasing AR dye concentration in the UV–Vis region (200–600 nm). A 2.0wt % AR/PVA composite film of thickness 250 ± 30 µm can entirely block light in the 200–600 nm wavelength region and can effectively block high power laser irradiation (10.7 mW) of wavelength 544 nm for a period of 60 min without degrading itself, which makes AR/PVA a potential candidate for flexible, high power laser filter in 200–600 nm region. A significant reduction in the band gap (~ 3.1 eV) is also observed for the composites than that of the neat PVA. The dielectric constant (\(\varepsilon^{\prime}\)) is found to be increased significantly with incorporation of AR dye and an optimum value of \(\varepsilon^{\prime} =\) 208 (at 40 Hz and 300 K) is obtained for 2.0% AR/PVA with small \(\tan \delta\) value (~ 0.56). Temperature-dependent dielectric properties of the composites are also investigated which confirm the dominating role of the interfacial polarization and presence of multiple dielectric relaxation processes. The enhanced laser filtering and dielectric properties of the AR/PVA composites can be attributed to the formation of hydrogen bond-mediated complexes in the composites. The fabricated novel AR/PVA composites can be potentially used in flexible, low-cost laser filter and flexible energy storage devices.