Patterned electrodeposition of CdTe nanorod and nanotube arrays for solar cells

Abstract

CdTe nanorod and nanotube arrays have been grown on indium tin oxide-coated glass slides through confined electrodeposition on lithographically patterned nanoelectrodes. While pattern definition by e-beam lithography yielded thinner nanorods and nanotubes, pattern definition by nanosphere photolithography using polystyrene spheres as lenses was successful in creating these nanowire arrays over a large area exceeding several square cm in a single step. The successful creation of clean arrays of nanotubes with uniform diameters underlined the versatility and uniqueness of the protocol. The photoconversion efficiencies of the nanorod/nanotube arrays were determined through photoelectrochemical response under ultraviolet light excitation. The observed photocurrent density of the fabricated nanorod device was more than two times higher than that of thin films fabricated under similar conditions, in spite of having a much lesser surface coverage for the nanorod device (~12% compared to the thin-film device). In addition to the potential of improved solar energy conversion efficiency by the nanorod and nanotube arrays, reduced material consumption due to lower coverage and simplicity of the fabrication technique make this approach ideal for the production of high-efficiency photovoltaic devices at commercial scale. This article contains supporting information that will be made available online once the issue is published.