Solar cells are provided with carbon nanotubes (CNTs) which are used: to define a micron/sub-micron geometry of the solar cells; and/or as charge transporters for efficiently removing charge carriers from the absorber layer to reduce the rate of electron-hole recombination in the absorber layer. A solar cell may comprise: a substrate; a multiplicity of areas of metal catalyst on the surface of the substrate; a multiplicity of carbon nanotube bundles formed on the multiplicity of areas of metal catalyst, each bundle including carbon nanotubes aligned roughly perpendicular to the surface of the substrate; and a photoactive solar cell layer formed over the carbon nanotube bundles and exposed surfaces of the substrate, wherein the photoactive solar cell layer is continuous over the carbon nanotube bundles and the exposed surfaces of the substrate. The photoactive solar cell layer may be comprised of amorphous silicon p/i/n thin films; although, concepts of the present invention are also applicable to solar cells with absorber layers of microcrystalline silicon, SiGe, carbon doped microcrystalline silicon, CIS, CIGS, CISSe and various p-type II-VI binary compounds and ternary and quaternary compounds.