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

Traektoriâ Nauki, Vol. 4, No. 7, pp. 3001-3012, 2018, DOI: 10.22178/pos.36-5

12 Pages Posted: 15 Jan 2019

See all articles by Nicholas Musila

Nicholas Musila

Kenyatta University

Mathew Munji

Kenyatta University

Justus Simiyu

University of Nairobi

Eric Masika

Kenyatta University

Raphael Nyenge

Kenyatta University

Date Written: July 31, 2018

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 extra-ordinary chemical stability. TiO2 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 TiO2 thin films determine the performance of dye sensitized solar cell fabricated from TiO2 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 TiO2 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 TiO2 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 TiO2 nanoparticles were spongy and had unevenly sphere-shaped profile while TiO2 nanotubes had a skein-like morphology with abundant number of nanotubes intertwined together. This study showed that TiO2 thin films have both direct and indirect band-gaps. The OJL Gap energy (E0) 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 TiO2 films prepared could be used in the fabrication of high performing dye-sensitized solar cell.

Keywords: TiO2 nanotube thin films; density of states; OJL model parameters; OJL Gap energy; spray pyrolysis

Suggested Citation

Musila, Nicholas and Munji, Mathew and Simiyu, Justus and Masika, Eric and Nyenge, Raphael, Optical Properties and Analysis of OJL Model’s Electronic inter-band Transition Parameters of TiO2 Films (July 31, 2018). Traektoriâ Nauki, Vol. 4, No. 7, pp. 3001-3012, 2018, DOI: 10.22178/pos.36-5. Available at SSRN: https://ssrn.com/abstract=3310510

Nicholas Musila (Contact Author)

Kenyatta University ( email )

P.O. Box 43844
Nairobi, Nairobi 00100
Kenya

Mathew Munji

Kenyatta University ( email )

P.O. Box 43844
Nairobi, Nairobi 00100
Kenya

Justus Simiyu

University of Nairobi ( email )

Nairobi
Kenya

Eric Masika

Kenyatta University ( email )

P.O. Box 43844
Nairobi, Nairobi 00100
Kenya

Raphael Nyenge

Kenyatta University ( email )

P.O. Box 43844
Nairobi, Nairobi 00100
Kenya

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