Synthesis and aging effect of plasma-polymerized 2-furancarboxaldehyde amorphous thin films

Monomer 2-Furancarboxaldehyde (FCD) deposited via glow discharge technique onto glass substrates to produce plasma synthesized 2-Furancarboxaldehyde (PPFCD) thin films with different thicknesses. The various characteristics, such as the structural, optical, morphological and elemental properties of unaged (as deposited) as well as aged PPFCD thin films were studied using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) absorption spectroscopy, environmental scanning electron microscopy (ESEM), and energy dispersive X-ray spectroscopic (EDAX) methods. The XRD studies indicated the existence of small crystallite domains or amorphous nature of the PPFCD films. The ESEM micrographs exhibited the uniform, pinhole, and fracture free surface of PPFCD films together with no queerish morphological variations due to the aging effect. On the contrary, the EDAX and FTIR spectroscopic studies illustrated some structural rearrangement owing to the aging of PPFCD thin films. The UV-Vis studies revealed that the direct and indirect optical band gaps (E-db and E-ib), and steepness parameter (sigma) of the aged PPFCD films were significantly reduced from 3.43 to 3.20 eV, 2.18 to 1.53 eV, and 0.0546 to 0.0524 respectively while the Urbach energy (E-u) value was slightly enhanced from 0.48 to 0.50 eV. This indicated that the aging has remarkable effects on the optical properties of the PPFCD films.