ARTICLES

Dye-sensitized nanocrystalline solar cells (DSC) provide aneconomically credible alternative to conventional inorganicphotovoltaic devices. Owing to their high-energy conversion efficiency and low production cost, they have received considerable attention over the past decade1−4. The mesoscopic texture of the TiO2 film in these cells significantly increases the cross-section of light harvesting by surface-anchored charge-transfer sensitizers, while maintaining a good contact with electrolytes. In these photovoltaic devices, ultrafast electron injection from a photoexcited dye into the conduction band of an oxide semiconductor, and subsequently dye regeneration and hole transportation to the counter electrode, are responsible for the efficient generation of electricity. Although a respectable 10.4 % light-to-electricity conversion efficiency at air mass (AM) 1.5 solar irradiance has been obtained for photovoltaic devices with a panchromatic dye and a liquid electrolyte containing the triiodide/iodide couple5, the achievement of long-term stability at temperatures of about 80–85°C,which is an important requirement fo