Effect of heat treatment on morphological, structural and optical properties of CoMTPP thin films

The morphologies and crystal structures of 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H-porphine cobalt(II), CoMTPP, thin films were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. Optical constants namely the refractive index, n, and the absorption index, k, of CoMTPP were estimated by using spectrophotometric measurements of transmittance and reflectance in the spectral range from 200 to 2500 nm. The dispersion of the refractive index in terms of the single oscillator in the transparent region is discussed. The single oscillator energy (E0), the dispersion energy (Ed), the high frequency dielectric constant (ɛ∞) and the lattice dielectric constant (ɛL) were calculated. The analysis of the spectral behavior of the absorption coefficient in the intrinsic absorption region reveals two indirect allowed transitions for as-deposited and annealed films.

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