eng Science and Education Publishing Journal of Materials Physics and Chemistry 2333-4444 2021-08-18 9 1 20 25 10.12691/jmpc-9-1-4 JMPC2021914 article Patrick Muvaka muvakapatwork@gmail.com 1 Waweru Mugo 1 Richard Ongeri 1 Mbiyu Ngaruiya 1 Department of Physics, Faculty of Applied Sciences, Jomo Kenyatta University of Agriculture and Technology (JKUAT), Nairobi, Kenya 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. http://pubs.sciepub.com/jmpc/9/1/4/jmpc-9-1-4.pdf vanadium dioxide transition temperature near-infrared-radiation luminous transmittance solar modulation ability and crystallinity