SiC and MoS 2 synergy in PVA/PVP for tunable opto-dielectric properties

Polyvinyl alcohol (PVA)–polyvinyl pyrrolidone (PVP) (60/40 wt%) nanocomposite films containing a fixed 5 wt% of molybdenum disulfide (MoS2) and varying amounts of silicon carbide (SiC) (0, 1, 3, and 5 wt%) were synthesized by the solution casting technique. The structural, optical, photoluminescence, and dielectric properties of the resulting films were systematically investigated using XRD, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, and LCR measurements. XRD analysis revealed broad peaks at 2θ = 19.56° and 40.87°, corresponding to PVA/PVP, with reduced intensity and increased amorphousness upon filler incorporation. The UV–Vis spectra showed that absorption in the UVA, UVB, UVC, and visible regions increased with rising SiC content, while transmittance decreased significantly, reaching minimum values of 1–11% in the visible range at 5 wt% SiC. The direct and indirect optical band gaps decreased from 5.08 and 4.83 eV for the pristine PVA/PVP blend to 2.44 eV and 1.51 eV at 5 wt% SiC, respectively. The refractive index reached its highest value of 2.277 at 600 nm for the sample containing 3 wt% SiC. The optical dielectric constant, energy density, and nonlinear optical parameters were enhanced, with the 3 wt% SiC sample exhibiting the highest energy density and nonlinear optical response. Photoluminescence intensity varied with SiC content: it decreased at 320 nm excitation but increased in the 350–550 nm range at 380 nm excitation. Dielectric measurements showed that the MoS2-only sample possessed the highest real and imaginary parts of the dielectric constant, while blends containing 3 or 5 wt% SiC exhibited increased geometric capacitance. AC conductivity and impedance analysis further revealed composition-dependent electrical behavior. These results indicate that the dual-filler PVA/PVP/MoS2/SiC nanocomposites are promising candidates for UV-shielding coatings and show potential for optoelectronic and flexible energy-storage applications. However, no comparative data with commercial UV-blocking materials are presented here, and device-level validation—such as UV-shielding efficiency, solar-cell efficiency, supercapacitor cycling, and switching speed—is required and is beyond the scope of this materials-characterization study.