Dye-Sensitized Solar Cells Fabricated From Atomic Layer Deposited Photoanodes on Aerogel Scaffolds

Dye-sensitized solar cells (DSSCs) based on mesoporous, high surface area nanocrystalline titania (TiO2) exhibiting up to 11% solar energy-conversion efficiencies are promising materials for cost-effective devices. Our objective here is to realize a costeffective fabrication technique coupled with suitable device architecture of nanostructured DSSCs to achieve high photoconversion efficiencies. Atomic layer deposition (ALD) offers an attractive synthetic route for fabricating conformal photoanode coating materials on a nanoporous scaffold. Here, we used silica aerogels processed by doctor blading as structural scaffolds on transparent conducting oxide substrates, to promote subsequent conformal growth of thin films of TiO2 and aluminumdoped zinc oxide (AZO) by ALD. The resulting interdigitated architecture of the photoanodes can facilitate fast electron transfer. Dye sensitization of the photoanodes was accomplished using ditetrabutylammonium cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'dicarboxylate)ruthenium(II) (“N719”, Dyesol, B2 dye) and assembled into photocells using liquid electrolytes. Cosensitization with a second dye was found to increase the photon absorption and cell efficiency.