FIG. 4 Photocurrent-voltage characteristics of a cell, based on a colloidal TiO<sub>2</sub> film sensitized by <strong>1</strong>; the film, supported on a conducting glass sheet, was used in a sandwich-type configuration. The size of the dye coated TiO<sub>2</sub> photoanode was 0.5 cm<sup>2</sup>. The counterelectrode, consisting of conducting glass coated with a few monolayers of platinum, was placed directly on top of the working electrode. A thin layer of redox electrolyte is attracted into the intra-electrode space through capillary forces. The cell was exposed to simulated sunlight with AM1.5 spectral distribution. a. light intensity 83 W m<sup>-2</sup>, electrolyte: 0.5 M tetrapropylammonium iodide +0.04 M iodine in a mixture of ethylene carbonate (80% by volume) with acetonitrile. Fill factor was 0.76; surface area 0.5 cm<sup>2</sup> (before multiplication by roughness factor). Conversion efficiency was 7.9%. b. light intensity 750 W m<sup>-2</sup>, electrolyte: 0.5 M tetrapropylammonium iodide, 0.02 M KI x 0.04 M I<sub>2</sub> in the same solvent. Fill factor was 0.684: conversion was 7.12%.