Mesoporous hierarchical anatase for dye-sensitized solar cells achieving over 10% conversion efficiency

Interest in both one-dimensional and hierarchical architectures of metal oxide semiconductors has intensified within the field of materials science over recent years. Herein, a new mesoporous anatase TiO2 architecture that combines these two concepts, as it is composed of individual, high-aspect-ratio, nanoribbon-like components, was synthesized via a facile hydrothermal method without any surfactant or template. An 8.3% solar-to-electric conversion efficiency was obtained when these structures were used in photoanodes for dye-sensitized solar cells, which are superior to commercial state-of-the-art TiO2 (6.6%), due to enhanced dye loading and efficient light scattering. To further improve the light scattering effect, a bi-layer structure was rationally designed (with this architecture as a scattering layer on top of a transparent, 12-μm-thick layer of nanocrystalline TiO2). A high efficiency of 10.3% was achieved, compared with an efficiency of 8.2% for the control electrode (optimized transparent/reflective commercial titania paste) with a scattering layer of similar thickness.