Correlation of Bond Energy and Optical Band Energy of Annealed TiO₂ Thin Films

Gitonga M. John^1, , Simon W. Mugo¹, James M. Ngaruiya¹, Nelson Mugambi¹ and Geoffrey G. Riungu¹

¹Department of Physics, Jomo Kenyatta University of Agriculture and Technology (JKUAT), Nairobi Kenya

Cite this paper:
Gitonga M. John, Simon W. Mugo, James M. Ngaruiya, Nelson Mugambi and Geoffrey G. Riungu. Correlation of Bond Energy and Optical Band Energy of Annealed TiO₂ Thin Films. American Journal of Energy Research. 2021; 9(1):1-5. doi: 10.12691/ajer-9-1-1

Abstract

We report on the correlation between bond energy and optical band energy of TiO₂ thin films prepared through sol gel doctor-blade technique. The TiO₂ films were deposited on doped fluorine tin IV oxide (SnO₂:F) layer on glass substrates. UV-Vis-NIR spectroscopy was carried out on as-deposited and subsequent annealed films at different rates from room temperature up to 450°C. The average optical transmittance within the visible region was 73.5%, 73.4%, 70.5% and 69.9% for the as-deposited, 1-step annealed, 2°C/min, and 1°C/min films, respectively. FTIR spectroscopy confirmed presence of functional elements of Ti = O with a peak at 587.7 cm^-1. Bond energy for the films was calculated using Madelung equation with inclusion of the second coordination sphere for crystalline state. The values of bond energies were found to be 3.99 eV, 4.02 eV, 4.12 eV and 4.16 eV for the as-deposited, 1-step annealed, 2°C/min, and 1°C/min films respectively. The analysis of the band gap was done using Tauc’s relation. Band gap energy ranged from 4.02 eV to 5.04 eV. A statistical correlation between bond energy and optical band energy was established. Films annealed at 1°C/min recorded the highest bond energy and lowest band gap energy. This is attributed to the process of nucleation and crystal growth which are governed by thermodynamic properties. Prolonged exposure to higher temperatures through low annealing rates led to formation of films with high bond energy and low band gap.

Keywords:
bonding energy optical band energy annealing rate TiO₂

This work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

References:

[1]	Elfanaoui, A., Elhamri, E., Boulkaddat, L., Ihlal, A., and Bouabid, K. (2011). Optical and structural properties of TiO2 thin films prepared by sol-gel spin coating. International Journal of Hydrogen Energy, 36: 4130-4133.
[2]	Tavares, C. J., Vieira, J., Rebouta, L., Hungerford, G., Coutinho, P., Teixeira, V., Carencro, J. O., and Fernandes, A. J. (2007). Reactive sputtering deposition of photocatalytic TiO2 thin films on glass substrates. Material Science Engineering, 138: 139-143.
[3]	Sung, Y. M., and Kim, H. J. (2007). Sputter deposition and surface treatment of TiO2 films for dye-sensitized solar cells using reactive RF plasma. Thin Solid Films, 515: 4996-4999.
[4]	Pulker H. K. (1999) Coatings on Glass. Elsevier, Amsterdam.
[5]	Yang, W., and Wolden, C. A. (2006). Plasma-enhanced chemical vapor deposition of TiO2 thin films for dielectric applications. Thin Solid Films, 515: 1708-1713.
[6]	Euvananont, C., Junin, C., Inpor, K., Limthongkul, P., and Thanachayanont, C., (2008). TiO2 optical coating layers for self-cleaning applications. Ceramics International, 34: 1067-1071.
[7]	Sta, I., Jlassi, M., Hajji, M., Boujmil, M. F, and Jerbi, R. (2014). Structural and optical properties of TiO2 thin films prepared by spin coating. Journal of Sol-Gel Science and Technology, 72: 421-427.
[8]	Serpone, N., Lawless, D., Khairutdinov, R. (1995). Size effects on the photophysical properties of colloidal anatase TiO2 particles: size quantization versus direct transitions in this indirect semiconductor. The Journal of Physical Chemistry, 99: 16646-16654.
[9]	Wang, W. H., and Chao, S. (1998). Annealing effect on ion-beam-sputtered titanium dioxide film. Optics letters, 23(18), 1417-1419.
[10]	Mathpal, M. C., Tripathi, A. K., Singh M. K., Gairola, S. P., and Pandey, S. N. (2013). Effect of annealing temperature on Raman spectra of TiO2 nanoparticles. Chemical Physics Letters, 555: 182-186.
[11]	Benjamin, M. J., Simon W. M., and James M. N. (2018). Effect of Annealing Rates on Surface Roughness of TiO2 Thin films. Journal of Materials Physics and Chemistry, 6(2): 43-46.
[12]	Norhafiezah, S., Ayub, R. M., Arshad, M. M., Azman, A. H., Fatin, M. F., Farehanim, M. A., and Hashim, U. (2014). The RF power effect on the surface morphology of titanium dioxide (TiO2) film. In Semiconductor Electronics (ICSE), IEEE International Conference. 48-51.
[13]	Amor, S. B., Baud, G., Jacquet, M., Pichon, N. (1998). Photoprotective titania coatings on PET substrates. Surface Coating Technology, 102: 63-72.
[14]	Sun, H., Wang, C., Pang, S., Li, X., Tao, Y., Tang, H., and Liu, M. (2008). Photocatalytic TiO2 films prepared by chemical vapor deposition at atmosphere pressure. Journal of Non-Crystalline. Solids, 354: 1440- 1443.
[15]	Mathews, N. R., Morales, E. R., Cortés-Jacome, M. A., and Antonio, J. T. (2009). TiO2 thin films-Influence of annealing temperature on structural, optical and photocatalytic properties. Solar Energy, 83(9), 1499-1508.
[16]	Ito, S., Kitamura, T., Wada, Y., and Yanagida, S. (2003). Facile fabrication of mesoporous TiO2 electrodes for dye solar cells: chemical modification and repetitive coating. Solar energy materials and solar cells, 76(1), 3-13.
[17]	Theiss, W. (2000). Scout thin films analysis software handbook, edited by Theiss M (Hand and Software Aachen German) www.mtheiss.com.
[18]	Hasan, M. M., Haseeb, M. A., Saidur, R., and Masjuki H. H. (2009). Effects of Annealing Treatment on Optical Properties of Anatase TiO2 Thin Films. World Journal of Nuclear Science and Technology. 40(2) 221-225.
[19]	Catherine, B., and Rainer, H. (2009). Fourier transform infrared (FTIR) spectroscopy. Photosynth Res. 101: 157-170.
[20]	Plotnikov, E. N., Lopatin, S. I., and Stolyarova, V. L. (2003). Application of the Sanderson Method to the Calculation of Bonding Energies in Oxide Glass-Forming Systems. Glass Physics and Chemistry, 29. (6), 517-521.
[21]	Habibi, M. H. Talebian, N. and Choi, J. H. (2007) The effect of annealing on photocatalytic properties of nanostructured titanium dioxide thin films, Dyes and Pigments, vol. 73, 2007, pp. 103-110.
[22]	Sta, I., Jlassi, M., Hajji, M., Boujmil, M.F., Jerbi, R., Kandyla, M., Kompitsas, M., and Ezzaouia, H. (2014). Structural and optical properties of TiO2 thin films prepared by spin coating. Journal of Sol-Gel Science and Technology, 72, 421.
[23]	Nair, B., Prabitha, & Justinvictor, V.B. & Daniel, Georgi & Joy, K. & Raju, James & Kumar, David & Varkey, P.V.Thomas. (2014). Optical parameters induced by phase transformation in RF magnetron sputtered TiO2 nanostructured thin films. Progress in Natural Science: Materials International. 24. 219-221.
[24]	Alam, M. J. and Cameron, D. C. (2002). Preparation and Characterization of TiO2 Thin Films by Sol-Gel Method. Journal of Sol-Gel Science and Technology, 25: 137-145.
[25]	Al-Shomara, S. M., Alahmad W.R. (2019). Annealing temperature effect on structural, optical and photocatalytic activity of nanocrystalline TiO2films prepared by sol-gel method used for solar cell application. Digest Journal of Nanomaterials and Biostructures, 14: 617-625.
[26]	Juraj M.F., C. MocanuV., Deringer L. Gábor C. and Stephen R. E. (2018). Similarity between Amorphous and Crystalline Phases: The Case of TiO2 Journal of Physical Chemistry, 9 (11), 2985-2990.