Nickel oxide sol–gel films from nickel diacetate for electrochromic applications

• Published in: Thin solid films Vol. 424; no. 2; pp. 165 - 170
• Main Authors: Garcia-Miquel, J.L, Zhang, Q, Allen, S.J, Rougier, A, Blyr, A, Davies, H.O, Jones, A.C, Leedham, T.J, Williams, P.A, Impey, S.A
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01.01.2003; Elsevier Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Deposition process; Electrochromism; Electrooptical effects; Exact sciences and technology; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Nickel oxide; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Sol–gel; Electrochromism; Sol–gel; Nickel oxide; Deposition process; Nickel oxides; Inorganic compounds; Sol-gel; Transition element compounds; Crystallization; Polycrystals; Experimental study; Heat treatments; Characterization; Thin films; Cyclic voltammetry; Optical properties; Electro-optical effects; Spin-on coating; Sol-gel process; Growth from solution; Nanocrystal
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(02)01041-6

Nickel diacetate tetrahydrate, [Ni(acetate) 2·4H 2O] and nickel diacetate dimethylaminoethanol, [Ni(acetate) 2(dmaeH) 2] were successfully used to deposit NiO x thin films on conductive glass substrates by sol–gel techniques for large area electrochromic applications. Homogeneous one layer films 100 nm thick were deposited by spin coating 0.5 M [Ni(acetate) 2·4H 2O] in dmaeH at 1000 rpm and by dip coating methods. The NiO x films were characterised by X-ray diffraction, transmission electron microscopy and atomic force microscopy. The thin film electrochromic performances were characterised by means of optical (transmittance) and electrochemical (cyclic voltammetry) methods. On early cycling NiO x thin films present an activation period, related to an increase in capacity. The electro-optical data show an increase in the electrochromic response (i.e. an increase in contrast and colouration efficiency) upon cycling. Following this initial activation period a steady state is reached in which the thin films reversibly switch from transparent to brown. The anodically coloured NiO x thin films are therefore suitable for use in a complete electrochromic cell with tungsten oxide as the cathodic colouring layer. However, the films are not fully stable with long cycling.