Dye-sensitized solar cells (DSSCs) offer many advantages in comparison to their Si-based counterparts, including lower cost of raw materials, faster manufacturing time, and the ability to be integrated with flexible substrates. Although many advances have been made in DSSC fabrication over recent years, their efficiency remains lower than commercially available Si photovoltaic cells. Here we report improved efficiency of TiO(2)/anthocyanin dye solar cell using vertically aligned arrays of carbon nanotubes (CNTs) as a counter electrode. Dense vertically oriented CNT arrays are grown directly on the counter electrode using microwave plasma chemical vapor deposition and a trilayer (Ti/Al/Fe) catalyst. The resulting arrays are 30 mu m in height and have a number density of approximately 5x10(8)/mm(2). By directly growing the CNTs on the counter electrode substrate, electrical interface conductance is enhanced. The performance of both as-grown and N-doped (using a nitrogen plasma) CNT arrays is reported. The fabricated DSSCs are tested under AM1.5 light. Increased short-circuit current is observed in comparison to graphite and Pt counter electrodes. We attribute this improvement to the large surface area created by the 3D structure of the arrays in comparison to the planar geometry of the graphite and Pt electrodes, as well as the excellent electrical properties of the CNTs.
Available at: http://works.bepress.com/robert_sayer/5/