Thermochromic Properties of VO₂ Thin Films Derived from Thermal Reduction of Sol-Gel Deposited V₂O₅

Patrick Muvaka^1, , Waweru Mugo¹, Richard Ongeri¹ and Mbiyu Ngaruiya¹

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

Cite this paper:
Patrick Muvaka, Waweru Mugo, Richard Ongeri and Mbiyu Ngaruiya. Thermochromic Properties of VO₂ Thin Films Derived from Thermal Reduction of Sol-Gel Deposited V₂O₅. Journal of Materials Physics and Chemistry. 2021; 9(1):20-25. doi: 10.12691/jmpc-9-1-4

Abstract

Vanadium dioxide (VO₂) thin films were prepared by thermal reduction of vanadium pentoxide (V₂O₅) films and thermochromic properties of the films were investigated. V₂O₅ films were prepared by dip-coating glass substrates at different withdrawal speeds of 5, 10, 15, and 20 mm/min. The as-deposited V₂O₅ films were annealed at different temperatures of 450, 500, 550 and 600°C in an inert environment of flowing argon gas under normal atmospheric pressure. The as-deposited V₂O₅ films were gray in color and the films changed color to golden yellow after annealing. UV-VIS-NIR spectrophotometry and sheet resistance probe were used to evaluate performance of the films. The result shows that a withdrawal speed of 5mm/min and annealing temperature of 500°C produced homogeneous VO₂ films with luminous transmittance close to the desired transmittance threshold for day-lighting. This was attributed to reduced thickness and crystallization resulting to low absorption by VO₂. Results showed that 500°C was threshold for obtaining crystalline VO₂ films. UV-VIS-NIR analysis revealed solar modulation ability of 5.2%, large transmittance change of over 35°C in the IR region and hysteresis loop of 6.0°C when going through phase transition between 25°C and 90°C. Temperature dependence of sheet resistance revealed semiconductor to metal transition behavior change of 2 orders of magnitude across transition temperature. The film showed semiconductor to metal transition temperature of 61.2°C lower than the classical value of 68°C and was attributed to crystalline structure of the films. This simple solution process followed by thermal reduction makes the VO₂ potentially useful in smart window application.

Keywords:
vanadium dioxide transition temperature near-infrared-radiation luminous transmittance solar modulation ability and crystallinity

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References:

[1]	Morin F.J., (1959). Oxides which show a metal-to-insulator transition at the knee temperature, physical review letters, 318 (5857): 1750-1753.
[2]	Wu J., Lan Z., Hao S., Li P., Lin X., Huang M., Fang L. and Huang Y., (2008). Progress on the electrolytes for dye-sensitized solar cells. Pure Applied Chemistry. 80 (11): 2241-2258
[3]	Babulanam F.S, Erickson T., Niklasson G. and Granqvist C., (1987). Thermochromic VO2 films for energy efficient windiows, Solar energy materials, 83(3): 347-363.
[4]	Granqvist C., Green S., Niklasson G.A., Mlyaka N.R., Kraemer S.V., and Georen P., (2010), Advances in chromogenic materials and devices, Thin solid films, 518(11): 3046-3053.
[5]	Goodenough J.B, (1971), The two components of the crystallographic transition in VO2, Journal of solid state chemistry, 3(4):490-500.
[6]	Shin S. Suga M., Taniguchi M., Fujisawa M., Kanzaki H., Fujimori A., Daimon H., Ueda Y., Kosuge K. and Kachi H., (1990). Vacuum-ultraviolet reflectance and photoemission study of the metal-insulator phase transitions in VO2, V6O13 and V2O3, Physical review letters, 41:4993-5009.
[7]	Kim H., Kim Y., Kim T.Y., Jang A.R., Jeong H.Y., Han S.H., Yoon D.H., and Shin H.S., (2013), Enhanced optical response of hybridized VO2/graphene films, Electronic supplementary material for nanoscale, 21: 463-816.
[8]	Li Y., Namura K., Suzuki M., Niklason A., and Granqvist, (2013). Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modelling, Journal of applied physics, 114(3):33516.
[9]	Monfort O., Roch T., Satrapinsky L., Gregor M., Plecenik T., Plecenik A. and Plesch G., (2014). Reduction of V2O5 thin films deposited by aqueous sol-gel method to VO2(B) and investigation of its photocatalytic activity, Journal of applied surface science, 322: 21-27.
[10]	Ningyi Y., Jinhua L. and Chenglu L., (2012). Control of thermochromic spectrum in vanadium dioxide by armophous silicon suboxide layer. Solar energy materials and solar cells, 191: 176-180.
[11]	Sanjeev S. and Kekuda D., (2015). Effect of annealing temperature on the structural and optical properties of Zinc oxide (ZnO) thin films prepared by spincoating process, material science and engineering, 73: 012149.
[12]	Kim H., Horwitz J.S and Kushto G., (2000). Effect of film thickness on the properties of indium tin oxide thin films, Journal of applied physics, 80 (10): 6021-6025.
[13]	Miller M.J and Wang J. (2015), Influence of grain size on transition temperature of thermochromic vo2, Journal of applied physics, 117 (034307).
[14]	Whitaker L., Jaye C., Fu Z., Fisher D.A., and Banerjee S., (2009). Depressed phase transition in solution grown VO2 nanostructures, J. Am. Chem.Soc. 131(25): 8884-8894.
[15]	Qi M., Wei M., Ichihara M., Hirabayashi M., Honma I. and Zhou H., (2006). Synthesis of single-crystal vanadium dioxide nanosheets by the hydrothermal process, Journal of crystal growth, 296(1): 1-5.
[16]	Wu J., Lan Z., Hao S., Li P., Lin X., Huang M., Fang L. and Huang Y., (2008). Progress on the electrolytes for dye-sensitized solar cells. Pure Applied Chemistry. 80 (11): 2241-2258.
[17]	Jin P., Xu G., Tazawa M. and Yoshimura K. (2003), Design, formation and characterization of novel multifunctional window with VO2 and TiO2, Applied physics, 77: 455-459.
[18]	Beteille F and Livage J., (1998). Optical switching in vo2 thin films, Jounal of sol-gel science technology, 13:915-921.
[19]	Liu y., Liu J., Li y., Wang D,. Ren L. and Zou K., (2018). Effect of annealing temperature on the structure and properties of vanadium oxide films, material science and engineering. (6) : 5.
[20]	Hashim H., Rafiq M. and Yazid I. M., (2018). Investigation of annealing temperature on vanadium thin films, international journal of Engineering and technology, 655,(20).
[21]	Kuo C.C., Liu C.C., He S.C., Chang J.C and He J.L, (2011). The influence of thickness on the optical and electrical properties of Dual-Ion- Beam sputtering-deposited molybdenum-doped zinc oxide layer, 85: 961.
[22]	Simoes A.Z., Zaghete M.A., Cilense M., Varela J.A. and Stojanovic B.D., (2001). Preparation of 9/65/35 PLZT thin films deposited by a dip-coating process, Journal of the European ceramic society, 21:1151-1157.
[23]	Zhang Z., Gao Y., Chen., Du J., Cao C., Kang L and Luo H., (2010). Thermochromic vo2 thin films: Solution based processing to improve optical properties and lowered phase transformation temperature, 26(13):10738-10744.
[24]	Xun. C and Ping J. (2018). Solar modulation utilizing VO2 based thermochromic coatings for energy-saving applications, emerging solar energy materials 5: 3401-3422.
[25]	Li s. (2013). VO2-based thermochromic and Nanothermochromic materials for energy-efficient windows,Dissertation from the faculty of science and technology-uppsala university Sweden, 1095: 143.