Incident-photon-to-current-conversion efficiency of TiO2 photoanodes is increased significantly in the visible and near infrared range of the electromagnetic spectrum by assembling films that are structured on both micrometer and nanometer length scales. Photoanodes assembled from alternating layers of TiO2 nanoparticles and mesoporous TiO2 microspheres increase the overall power conversion efficiencies of dye-sensitized solar cells by as much as 26. This increase is due to enhanced light scattering by porous TiO2 microspheres and is achieved without sacrificing the specific surface area.
Bibliographical noteFunding Information:
This work was supported primarily by the MRSEC Program of the National Science Foundation under Award Number DMR-0819885. Part of this work was carried out (i) in the Institute of Technology Characterization Facility, University of Minnesota, which has received capital equipment funding from the NSF through the MRSEC, ERC, and MRI programs, and (ii) in the Minnesota Characterization Facility, which receives partial support from the NSF-NNIN program. We thank Ankur Khare for assistance with TEM/HRTEM and Professor Lorraine Francis and David Norris for discussions on drop casting from colloidal suspensions.
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