%0 Journal Article
%T Self-Organized One-Dimensional Nanotube/Nanowire Array Films for Use in Excitonic Solar Cells: A Review
%A Ningzhong Bao
%A Xinjian Feng
%A Craig A. Grimes
%J Journal of Nanotechnology
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/645931
%X We review the use of self-assembled, vertically oriented one-dimensional (1D) titania nanowire and nanotube geometries in several third-generation excitonic solar cell designs including those based upon bulk heterojunction, ordered heterojunction, F£¿rster resonance energy transfer (FRET), and liquid-junction dye-sensitized solar cells (DSSCs). 1. Introduction Third-generation photovoltaics encompass a variety of designs including liquid-based dye-sensitized (Gr£¿tzel) solar cells, solid-state bulk heterojunction solar cells [1¨C6], ordered heterojunction solar cells [7, 8], F£¿rster resonance energy transfer- (FRET-) based solar cells [9¨C14], and organic solar cells [15, 16]. Liquid-based dye-sensitized solar cells (DSSCs) utilizing for a photoanode a dye-coated layer of TiO2 nanoparticles have reached efficiencies of over 11% [17], but there are concerns with respect to manufacturing photovoltaic panels with a liquid redox electrolyte. Solid-state organic solar cells are easy to handle and manufacture, and have demonstrated efficiencies ranging from 2 to 8.13% [18¨C20]. Other 3rd generation photovoltaic designs include plasmonic resonance devices [21], quantum dot and, hopefully, multiple exciton devices [22, 23]. Various nanostructures have been used as a means of energy conversion enhancement in 3rd generation solar cells. These structures can be classified into four types: (a) Nanocomposite (3-dimensional), (b) quantum well (2-dimensional), (c) nanowire and nanotubes (1-dimensional, 1D), and (d) nanoparticles (0-dimensional). Our interest in this paper is the photovoltaic application of self-assembled TiO2-based 1D nanostructures. Self-organized TiO2 nanowires/nanotubes arrays [24, 25] vertically oriented on a transparent conducting oxide (TCO) substrate offer numerous benefits such as large surface area for dye sensitization resulting in enhanced light harvesting, easy transfer of electrons injected from photon excited dye, vectorial (directed) charge transport to the electrical contact, and a readily assessable space for intercalation of the redox electrolyte or p-type semiconductor. However, while self-assembled vertically oriented 1D titania nanoarchitectured films offer great potential for enhancing 3rd generation photovoltaic efficiencies to date, such films have not yet been achieved. There is, to date, something always lacking in such fields, be it poor crystallinity of the electron transporting backbone which results in poor charge transport, damage to the transparent conductive oxide coating which increases the series resistance and/or reduces
%U http://www.hindawi.com/journals/jnt/2012/645931/