Electrochromism in copper oxide thin films

Abstract

Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

Effect of Oxidation Temperature on Photo-catalytic Properties of Stainless Steel Coated by Copper Oxide

“…In previous studies, the electrical properties and photoelectrical ones of the oxide film on a glass and Cu sheet have been reported. [5][6][7][8] However, the relationship between photopotential and durability of the oxide film is not apparent. In addition, there are few works to report the effect of a substrate on the property of the electrode.…”

Effect of Manganese Contain on the Optical Properties of CuO Thin Films

“…Both the tenorite and cuprite were p-type semiconductors having band gap energy of 1.21 to 1.51 eV and 2.10 to 2.60 eV respectively [2,3]. CuO absorbs strongly throughout the visible spectrum and is black in appearance [4]. Copper oxide films have been deposited using several techniques such as oxidation of copper sheets [5], electrodeposition [6], ultrasonic spray pyrolysis [7], reactive sputtering [8],and chemical path deposition [9].Ferromagnetism has been observed for 15.2%-29.8% Mn doped CuO thin film with a transition temperature between 87.0 and 99.5 K [10].…”

Surface analysis of electrochromic CuxO films in their colored and bleached states

“…It is known that copper oxide thin films exhibit cathode electrochromism [5][6][7][8] , i.e., they are transparent for visible light in their oxidized state and almost black in their reduced state.…”

“…Thin Cu x O films can be deposited with different techniques: sputtering 8 , electrochemical deposition 9,10 , solgel-like dip technique 5,11 , thermal oxidation 12 , anode oxidation 13 or chemical-deposition method [14][15][16][17] . Chemically deposited Cu x O films were the subject of our previous research 17 and are the topic of our present interest.…”