Effect of annealing and UV irradiation on structural and optical properties of 6-(3, 4 Dimethoxyphenyl)-1-methyl-3-oxo-2-phenyl-2, 3-dihydro1Hpyrazolo [4, 3-b]-5-carbonitrile thin films

6-(3,4 Dimethoxyphenyl)-1-methyl-3-oxo-2-phenyl-2,3 dihydro1Hpyrazolo[4,3-b]-5-carbonitrile, DMOPC, is a newly synthesized organic compound. DMOPC showed polycrystalline structure and crystallizes in monoclinic crystal system. The deposited thin films showed nanocrystals embedded in amorphous medium. The optical constants of DMOPC films were estimated by using spectrophotometric measurements of transmittance and reflectance at nearly normal incidence of light in the spectral range 190–2500 nm. The dependence of absorption coefficient on the photon energy, annealing temperature and UV exposure time was determined and the analysis of the results showed that DMOPC undergoes indirect allowed optical transition. The optical band gap for pristine film is 2.82 eV and it decreases to 2.67 eV upon exposing the film to UV light. Annealing of the thin film decreased the energy gap slightly. The optical dielectric constants and dispersion parameters of DMOPCthin film are calculated and showed remarkable dependence on photon energy, UV exposure time and annealing temperatures.