Anodic Aluminum Oxide Templated Channel Electrodes via Atomic Layer Deposition A. B. F. Martinson a,b , J. W. Elam b , J. T. Hupp *,a , M. J. Pellin b a Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA b Argonne National Lab, Division of Materials Science, Argonne, Illinois 60439, USA Dye-sensitized solar cells (DSSCs) utilize high surface area metal oxide sintered particle networks to absorb molecular dyes and transport injected charge carriers. While this sintered particle architecture allows liquid electrolyte DSSCs to achieve efficiencies up to 11%, slow charge transport through the semiconductor network limits the amount of modification that can be made to the electrolyte and dye without adversely affecting the efficiency. The functionalization of anodic aluminum oxide membranes with thin films of transparent, semiconducting oxides via atomic layer deposition may allow for significantly faster charge transport. We demonstrate the fabrication of ZnO thin films within and upon commercially available anodic aluminum oxide membranes via atomic layer deposition. Introduction Dye sensitized solar cells (DSSCs) comprise an increasingly attractive alternative energy conversion technology.(1, 2) These photoelectrochemical cells use molecular dyes to sensitize high area, wide band gap semiconductor oxide photoanodes. Typically, a liquid electrolyte based on iodide/triiodide scavenges the hole left on the dye and shuttles it to a Pt-coated counter electrode where the circuit is completed. Solid-state (molecular or polymeric) hole scavenger/conductor have also been used.(2) The most efficient DSSCs convert AM1.5 solar insolation to electrical energy with 11% efficiency, but suffer from relatively poor photovoltages due to the overpotential needed to drive the dye regeneration reaction. Furthermore, they show less than optimal photocurrents due to insufficient light collection at wavelengths > 700 nm.(3) Compared to the most efficient nanocrystalline TiO 2 photoanodes, devices fabricated with ZnO electrodes show significantly lower conversion efficiencies (4%).(4-6) Despite superior recombination dynamics, poor dye loading and charge injection into ZnO reduce the total photocurrent yield.(7) Yet ZnO DSSCs continue to be actively investigated due to the ease with which alternative and potentially superior high-area semiconductor morphologies may be fabricated. Particularly interesting are nominally 1-D arrays. Compared with standard photoanodes based on sintered nanocrystalline particles, 1-D photoanodes should show significantly faster electron transport, owing to a more direct path to the conductive glass electrode combined with fewer sites for trapping electrons. To this end, several novel photoanode architectures have been fabricated, including but not limited to hydrothermally grown ZnO nanorod arrays, electrodeposited ZnO platelets, and TiO 2 pores formed via titanium anodization.(8-10) In the most successful application of this idea to date, a 1.5% efficient ZnO nanorod array has been shown to exhibit significantly faster transport compared to nanoparticle networks.(11, 12) The efficiency ECS Transactions, 6 (25) 389-394 (2008) 10.1149/1.2943259, ©The Electrochemical Society 389 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 211.71.30.97 Downloaded on 2014-10-14 to IP