5 to this website 4.5 h. The electrodes loaded

with the N719 dye were then washed with acetonitrile and dried in air. Platinum (Pt)-coated FTO glass (Nippon Sheet Glass, 8–10 Ω/□, 3 mm in thickness) served as the counter electrode, which was prepared by placing a drop of H2PtCl6 solution on an FTO glass and subsequently sintering the glass at 400°C for 20 min. The ZnO photoanode and the counter electrode were sealed together with a 60-μm-thick hot-melting spacer (Surlyn, DuPont, Wilmington, DE, USA), and the inner space was filled with a volatile electrolyte. The electrolyte was composed of 0.1 M lithium iodide, 0.6 M 1,2-dimethyl-3-propylimid-azolium iodide (PMII, Merk Ltd., Taipei, Taiwan), 0.05 M I2 (Sigma-Aldrich), and 0.5 M tert-butylpyridine (Sigma-Aldrich) in acetonitrile. Characterization The morphologies of the ZnO nanoparticle films were examined by field-emission scanning electron microscopy (FE-SEM; Nova230, FEI Co., Hillsboro, OR, USA). The crystalline phases of the ZnO films were determined by X-ray diffraction (XRD) using a diffractometer (X’Pert PRO, PANalytical B.V., Almelo, The Netherlands) with Cu Kα radiation. The thickness of the ZnO nanoparticle film was measured using a microfigure-measuring instrument (Surfcorder ET3000, Kosaka Laboratory Ltd., Tokyo, Japan). Dye loading of the photoelectrode was estimated

by desorbing the dye in a 10 mM NaOH aqueous solution and then measuring the absorbance of the solution GS-1101 molecular weight using UV–vis spectroscopy (V-570, Jasco Inc., Easton, MD, USA). Photovoltaic characterization was performed under a white light source

(YSS-100A, Yamashita Denso Company, Tokyo, Japan) with an irradiance of 100 mW cm−2 at an equivalent air mass (AM) of 1.5 on the surface of the solar cell. The irradiance of the simulated light was calibrated using a silicon photodiode (BS-520, Bunko Keiki Co., Ltd, Tokyo, Japan). Current–voltage (J-V) curves were recorded with a PGSTAT 30 potentiostat/galvanostat (Autolab, Eco-Chemie, Utrecht, The Netherlands). The evolution of the electron transport process in the cell was investigated using EIS, and the impedance measurements were preformed under AM 1.5 G illumination. The applied DC bias voltage Megestrol Acetate and AC amplitude were set at open circuit voltage (V OC) of the cell and 10 mV between the working and the counter electrodes, respectively. The frequency range extended from 10−2 to 105 Hz. The electrochemical impedance spectra were recorded using an electrochemical analyzer (Autolab PGSTAT30, Eco-Chemie) and analyzed using Z-view Selleck Roscovitine software with the aid of an equivalent circuit. Results and discussion Characteristics of ZnO films Mesoporous films composed of commercial ZnO nanoparticles were prepared by screen printing. The as-printed films were sintered at 400°C for 1 h before dye sensitization to remove organic materials in the screen-printing paste. The FE-SEM image in Figure 1 provides a typical top view of the sintered ZnO film, which is uniform and highly porous.