A flexible quasi-solid-state electrochromic device (ECD), assembled with a polymeric crystal composite electrolyte and tungsten oxide/nickel oxide (WO3/NiO) complementary system, is demonstrated in this study. The polymer composite, which is composed of a UV-cured ethoxylated trimethylolpropane triacrylate (ETPTA), propylene carbonate (PC) and ferrocene (Fc), is used as the electrolyte in the flexible quasi-solid-state ECD. The optimal composition ration of this composite is at the weight ratio of 15/85 for ETPTA/PC with 1 M LiClO4. For the cathodic electrochromic electrode, a flexible polyethylene terephthalate (PET) is used as the substrate, and indium-tin- oxide (ITO) and WO3 are deposited sequentially on the PET by sputtering. A NiO/ITO/PET electrode prepared by sputtering is used as the anodic coloring electrode. The thickness of ITO, WO3 and NiO film is 110, 70 and 60 nm, respectively. This flexible all-solid-state ECD fabricated with the polymeric crystal composite electrolyte shows an optical contrast of ca. 37.5% at 550 nm. The optical transmittance of the ECD at 550 nm can be reversibly modulated from 47.5% (bleached) to 10.0% (darkened), by applying potentials of 2.5 and 2.5 V, respectively.
 Niklasson, G.A. and Granqvist, C.G. (2007) Electrochromics for Smart Windows: Thin Films of Tungsten Oxide and Nickel Oxide, and Devices Based on These. Journal of Materials Chemistry, 17, 127-156. http://dx.doi.org/10.1039/B612174H
 Baetens, R., Jelle, B.P. and Gustavsen, A. (2010) Properties, Requirements and Possibilities of Smart Windows for Dynamic Daylight and Solar Energy Control in Buildings: A State-of-the-Art Review. Solar Energy Materials and Solar Cells, 94, 87-105. http://dx.doi.org/10.1016/j.solmat.2009.08.021
 Heuer, H.W., Wehrmann, R. and Kirchmeyer, S. (2002) Electrochromic Window Based on Conducting Poly (3,4-ethy- lenedioxythio-phene)poly(styrene sulfonate). Advanced Functional Materials, 12, 89-94. http://dx.doi.org/10.1002/1616-3028(20020201)12:2<89::AID-ADFM89>3.0.CO;2-1
 Andersson, P., Nilsson, D. and Svensson, P.O. (2002) Active Matrix Displays Based on All-Organic Electrochemical Smart Pixels Printed on Paper. Ad-vanced Materials, 14, 1460-1464. http://dx.doi.org/10.1002/1521-4095(20021016)14:20<1460::AID-ADMA1460>3.0.CO;2-S
 Kobayashi, N., Miura, S. and Nishimura, M. (2008) Organic Electrochromism for a New Color Electronic Paper. Solar Energy Materials and Solar Cells, 92, 136-139. http://dx.doi.org/10.1016/j.solmat.2007.02.027
 Mihelcic, M., Jerman, I. and Svegl, F. (2012) Elec-trochromic Ni1?xO Pigment Coatings and Plastic Film-Based Ni1?xO/TiO2 Device with Transmissive Light Modulation. Solar Energy Materials and Solar Cells, 108, 175-187.