Optical spectroscopy characterization of zinc tetra pyridel porphine (ZnTPyP) organic thin films

Thermal evaporation technique was used to grow thin films of tetra pyridel-porphine zinc (ZnTPyP) onto quartz substrate. Optical constants, namely refractive index n and absorption index k, of the as-deposited ZnTPyP thin films have been estimated via spectrophotometric measurements of the transmittance and the reflectance within the spectral range (200-2500) nm. Depending on the single oscillator and Drude models, some associated parameters including the oscillation energy Eo, the dispersion energy Ed the optical dielectric constant ε∞, the lattice dielectric constant εL and the ratio of the free carriers concentration to their effective mass N/m∗ were determined. Urbach curves include 2 various exponential regions with different slopes. The absorption analysis was performed with the purpose of concluding the scattering mechanism and the type of the electronic inter-band transition for the studied thin film. Also, different dispersion and absorption parameters were determined. In addition, at lower photon energy, the third order nonlinear susceptibility χ(3) and the nonlinear refractive index n2 were reported and interpreted.