Dye-Sensitized Solar Cell Constructed with Titanium Mesh and 3-D Array of TiO2 Nanotubes

We have designed and constructed dye sensitized solar cells based on new, 3-D configurations of TiO2 nanotubes. The overall efficiency of our best cells is 5.0% under standard air mass 1.5 global (AM 1.5 G) solar conditions, and the incident photon-to-current efficiency exceeds 60% over a broad part of the visible spectrum. Unlike prior nanotube-based cells where tubes are grown vertically in a 2-D array, the anodes of the present cells consist of tubes that extend radially in a 3-D array from a grid of fine titanium wires. The nanotubes are tens of micrometers in length, and the radial nature of the anode allows the photon absorption path length to exceed the electron transport distance (nanotube length). The cells are front-illuminated and do not require a transparent conductive oxide substrate at either the anode or cathode. The use of 3-D configured nanotubes and low-resistance titanium metal substrates are expected to enhance the performance and simplify the construction of large area dye-sensitized solar cells.