Exploring the dielectric, THz, optical, and structural evaluation of graphene/PMMA films for optoelectronic devices

Bakr, Ahmed M., Abdelfattah Darwish, A. A. Azab, and Amir Elzwawy.

Abstract

The presented research highlights the PMMA doping with reduced graphene amounts through a feasible approach. The formed structures are fully explored through XRD, SEM, EDX, UV, FTIR, Raman spectroscopy, THz, and dielectric studies. XRD results display the amorphous-like structure integration with a slight increase in the most characteristic peak upon graphene incorporation. XRD reveals the successful incorporation of graphene in the polymeric network, and the resulted crystallite size is around 25 nm. The morphological analysis by SEM illustrates the decent dispersion of graphene within the polymeric matrix. EDX elemental analysis designates a balanced incidence of carbon and oxygen, consistent with the PMMA molecular structure. FTIR spectroscopy elucidates the apparent bands of the PMMA validating the interaction occurrence and spectroscopic alteration. The optical results demonstrate an occurring reduction in the energy band gap from 4 to 3.5 for the highest graphene ratio, are attributed to more incorporated energy levels in the structure. Raman spectroscopy displays that the I_D/I_G ratio was close to 1 which indicates less distortion and defects in the structures. The THz pulse displayed retard in time after reproducing via the films, and this related to the phase shift of the THz wave included in the THz pulse. Dielectric studies report an upsurge in conductivity and permittivity. Notably, the dielectric loss (ε″) and dielectric permittivity (ε′) reach 10 and 20 at 70 °C. Inherently, a direct proportionality is obtained or the dielectric parameters with raised temperature within (−10–70 °C). The explored results demonstrated the suitability of the prepared composites for potential applications in optoelectronics and nanotechnological directions.

Full paper can be viewed here.