Investigation of optical transition energy in copper phthalocyanine by transmission, reflection and photoreflectance spectroscopy

The thin layer of copper phthalocyanine (CuPc) deposited on glass substrate was investigated by transmission (T), reflection (R) and sensitive modulated photoreflectance (PR) spectroscopy. All measurements were carried out in 400–1200 nm spectral region at room temperature. The energy of observed transitions and its broadening parameter were determined by fitting Aspnes formula to photoreflectance spectrum. The absorption coefficient α (and the extinction coefficient k) was directly found from the transmission spectrum and treat with the help of multioscillator Lorentz model modified by the Lorentz–Lorenz formula. Spectral distribution of complex refractive index and dielectric constants (real ε1 and imaginary ε2 part) were also found from reflection and transmission spectra. Model with two oscillators was used to fit the experimentally observed optical functions of copper phthalocyanine (CuPc).