Improved efficiency of smooth and aligned single walled carbon nanotube/silicon hybrid solar cellsElectronic supplementary information (ESI) available: Microscope images, ideality factor calculation, sheet resistance and transmittance results, J-V characteristics in the semi-logarithmic scale at the forward linear region. See DOI: 10.1039/c2ee23716d

Smooth and aligned single walled carbon nanotube (SWNT) thin films with improved optoelectronic performance are fabricated using a superacid slide casting method. Deposition of as made SWNT thin film on silicon (Si) together with post treatments result in SWNT/Si hybrid solar cells with unprecedented high fill factor of 73.8%, low ideality factor of 1.08 as well as overall dry cell power conversion efficiency of 11.5%. Record-breaking smooth and aligned single walled carbon nanotube/silicon hybrid solar cells are fabricated by engineering the carbon nanotube/silicon interface properties.