Thermal annealing impact on structural, optical and dispersion parameters of zinc tetrapyridylporphyrin as a potential absorber thin film for energy conversion and storage devices

Thermally evaporated of zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP) organic thin films have been successfully prepared and investigated. X-ray diffraction patterns of fresh grown and annealed ZnTPyP thin films have been performed. Spectra of transmission (T) and reflection (R) have been measured and have been used to establish optical constants and relevant dielectric variables. The absorption spectrum of pristine and annealed ZnTPyP films shows the most intense band called Soret band (B) which reveals Davydov splitting into two peaks Bx and By. Furthermore, two quasi-electronic bands named Q-bands and another weaker band labelled N have been observed at UV–visible spectral region. To derive several dispersion parameters of the studied ZnTPyP films, a single oscillator theory is implemented to the normal behaviour portion of the n-spectra whereas K-spectra is used to deduce the coefficient of absorption and the optical gap energies. Many optical aspects have also been discussed, such as dielectric constants, optical conductivity and energy loss functions (SELF and VELF). Optical constants, dispersion parameters and energy loss functions of ZnTPyP thin films have shifted with the thermal annealing range up to 523 K, which could be considered in design the energy conversion and storage devices based on ZnTPyP thin films.