Available online at www.sciencedirect.com ScienceDirect Materials Today: Proceedings 17 (2019) 1780–1786 www.materialstoday.com/proceedings 2214-7853 © 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of The First Materials Research Society of Thailand International Conference. MRS-Thailand 2017 Effect of CuS:WO 3 ratio on the Photochromic properties of CuS-WO 3 film Anan Junsukhon a , Pailin Ngaotrakanwiwat a,b,c, * a Department of Chemical Engineering, Burapha University, Chonburi 20131, Thailand b Research Unit of Developing Technology and Innovation of Alternative Energy for Industries, Burapha University, Chonburi 20131, Thailand c Nanotec-KMUTT Center of Excellence on Hybrid Nanomaterials for Alternative Energy (HyNAE), School of Energy, Environment and Materials, king Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand Abstract Controlling light and heat penetration through building is of considerable interest. Smart window is a promising device to control them. The smart window is generally composed of metal oxide, i.e. WO 3 , which is widely used as photochromic materials because of adjustable transmittance under UV light, CuS which exhibits low reflectance in visible light, in contrast to high absorbed in the near-infrared light. The optical properties of CuS-WO 3 films fabricated at different conditions were investigated. The optical properties of the films were characterized by spectrophotometer for color. The difference of color in CIE scale before and after irradiations was determined by color contrast (∆C) and initial coloration rate (∆C/min). Under UV irradiating intensity of 5 mW/cm 2 , transparent CuS-WO 3 film changed to dark blue color, while no difference in coloration under incandescent irradiation. The molar ratios of CuS: WO 3 in films were varied from 1:0.1 to 1:0.4 and oxygen concentrations in drying chamber were in a range of 0 – 100 mol%. The color contrasts of WO 3 films was increase relatively with amount of WO 3 , prepared at molar ratio = 1:0.4 and 0% oxygen. It was 81.7 which is 1.2 times of color contrast and its initial coloration rate is 1.14 times of 0.75WO 3 film (equal amount of WO 3 ) and 0%oxygen. The difference in coloration decreased while increasing oxygen concentrations in drying chamber. It was 67.37 which is 1.23 times of color contrast and its initial coloration rate is 1.27 times of 0.75WO 3 and 100%oxygen because oxygen concentrations in drying chamber may be bring oxygen vacancy. © 2019 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of The First Materials Research Society of Thailand International Conference. Keywords: WO 3 ; CuS ; photochromic ; smart window * Corresponding author. Tel.: +66-3810-2222; fax: +66-3874-5806. E-mail address: pailin@eng.buu.ac.th