On the dielectric and photoluminescence characterizations of single-walled carbon nanotube/polymer composites

Abstract

A glass fiber reinforced polymer (GFRP) nanocomposite incorporating single-walled carbon nanotubes (SWCNTs) was fabricated to investigate the effects of nanotube incorporation on the optical and dielectric properties. Photoluminescence (PL) measurements were performed to characterize the optical properties of the carbon nanotube–reinforced nanocomposite. Luminescence spectra and the chromaticity diagram were recorded in the wavelength range of 350–900 nm at room temperature. Additionally, PL spectra of the material were obtained at varying temperatures ranging from 10 to 300 K. The emission spectrum of the SWCNT-reinforced nanocomposite exhibits intense emission features, with a prominent excitation at 349 nm. The nanocomposite exhibits a strong emission peak at 398 nm corresponding to violet emission, along with a broad band spanning 420–520 nm in the blue–green region. It also shows a weak emission band at 758 nm in the near infrared (NIR) region. The Commission Internationale de l’Éclairage (CIE) chromaticity coordinates of the nanocomposite were determined as (0.205, 0.242), locating the emission near the boundary between the blue and green regions of the CIE diagram. These findings suggest that the synthesized nanocomposite is a promising candidate for solid-state lighting devices and light-emitting diode (LED) applications. The dielectric parameters and relaxation behavior of the unsaturated polyester matrix–based nanocomposite were analyzed using impedance spectroscopy over a broad frequency range. The real component of the complex dielectric permittivity, which is the dielectric constant, and the imaginary component, which is the dielectric loss, was calculated at different temperatures. It was observed that the nanocomposites exhibit high dielectric constants at low frequencies due to the Maxwell–Wagner–Sillars (MWS) interfacial polarization mechanism, which gradually diminishes at higher frequencies as polarization processes become less effective. Furthermore, dielectric loss responses exhibit similar trends with respect to both temperature and frequency variations.