A double-layer antireflection (AR) coating fabricated using the single Indium tin oxide (ITO) conductive material is proposed. The high refractive index of the bottom ITO layer was achieved by long-throw radio-frequency magnetron sputtering technique at room temperature. On the other hand, the top ITO layer with low refractive index was prepared by applying supercritical CO2 (SCCO2) treatment at 60 degrees C on gel-coated ITO thin films. Porous structures were obtained with the SCCO2 treatment to volatilize or extract organic matters from the films. Their refractive indices were precisely controlled by varying the sputtering power and the operation pressure of the long-throw sputtering and the SCCO2 treatment, respectively. Weighted average reflectance and average transmittance of 4.3% and 86.2% were achieved for the double-layer ITO AR electrode. In addition, the sheet resistance of the AR electrode is 1.14 k Omega/square with 65 nm thick porous ITO layer on 75 nm thick sputtered ITO layer. (C) 2012 Elsevier B.V. All rights reserved.