Enhancement of nonlinear optical susceptibility of CuPc films by ITO layer

In the present study, the Copper Phthalocyanine (CuPc)/ITO thin film was fabricated using thermal evaporation method. The structural property was analyzed by X-ray diffraction study and confirms that the thin film has been preferentially grown along (200) plane. The atomic force microscope study was carried out on deposited film and quality of thin films is assessed by calculating the roughness of the films. The direct and indirect band gap, linear and nonlinear optical characteristics of grown films were calculated by using UV–Vis–NIR spectrometer studies. The calculated values of the first direct and indirect band gaps (E_g1(d) & E_g1(ind)) are 1.879 and 1.644 eV as a fundamental gap, while the values of second direct and indirect band gap (E_g2(d) & E_g2(ind)) are 1.660 and 1.498 eV as an onset gap for CuPc. The values of nonlinear refractive index (n₂) and third order nonlinear optical susceptibility (χ³) are found to be 5 × 10⁻⁸ and 8 × 10⁻⁹ (theoretical) and 5.2 × 10⁻⁸ and 1.56 × 10⁻⁷ (experimental) respectively. The optical band and third order nonlinear properties suggest that the as-prepared films are may be applied in optoelectronic and nonlinear applications.