Optical Properties and Analysis of OJL Model’s Electronic inter-band Transition Parameters of TiO2 Films

Abstract

Titanium dioxide is a wide band gap semiconductor responsible for the bright white appearance in most substances. This material has many unique properties due to its extraordinary chemical stability. TiO 2 has a conduction band that closely matches the excited energy level of organic dyes hence it is used in fabrication of photo-anode electrode of dye sensitized solar cell. However, the optical properties and the density of states of TiO 2 thin films determine the performance of dye sensitized solar cell fabricated from TiO 2 photo-anode electrode. For this reason, the purpose of this study was to investigate the optical properties and the OJL electronic inter-band transition analysis of TiO 2 nanoparticle thin films. Under the OJL model, the expressions of density of states were specified for the optical transition from the valence band to the conduction band. The TiO 2 nanoparticles were prepared using sol-gel and hydrothermal methods and deposited on a conductive glass substrate by screen printing and spray pyrolysis techniques. SEM analysis revealed that TiO 2 nanoparticles were spongy and had unevenly sphere-shaped profile while TiO 2 nanotubes had a skein-like morphology with abundant number of nanotubes intertwined together. This study showed that TiO 2 thin films have both direct and indirect band-gaps. The OJL Gap energy (E 0) values were observed to be between 30273.2356 and 31072.0000 wavenumbers which translated to band-gap energies between 3.744 and 3.843 eV. From these findings showed that TiO 2 films prepared could be used in the fabrication of high performing dye-sensitized solar cell.

Optical properties of germania and titania at 1064 nm and at 1550 nm

“…For Run 3, only one sample was available. The measured spectra were analysed using the SCOUT software 7 in which three different optical models were compared: the Cauchy model [37] in the transparent region in the Visible-Near-Infrared (vis-NIR) range, the Tauc-Lorentz [38] and OJL models [39] in the whole range. While these models are used to investigate different spectral regions, they all cover the NIR region.…”

Controlling the optical properties of hafnium dioxide thin films deposited with electron cyclotron resonance ion beam deposition

“…Where E 0 can be acquired via SCOUT. The other OJL interband transitions within SCOUT are as follows [30,31,33,34]:…”