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We report on the improvement of power conversion efficiency (PCE) of PTB7/PC70BM solar cells by the addition of small quantities (0.02%-0.04%) of pristine single-walled carbon nanotubes (SWNTs) in the active-layer. SWNTs and purified semiconducting SWNTs (S-SWNTs) were added in quantities, which is 2 orders of magnitude lower than previously reported value and resulted in a reduction in the series resistance of the solar cell with minor changes on the shunt resistance. On addition of purified S-SWNT, the PCE of air measured devices enhanced by 29% from 4.9% to 6.3%, with short-circuit current density (JSC) improving from 12.1mA/cm² to 14.4 mA/cm² and a fill factor improvement from 54% to 61%. In addition, the role of processing additive N-Methyl-2-pyrrolidone, which acts as a SWNT dispersant, is also investigated. A single diode model of a solar cell is used to extract the cell parameters and understand the effect of SWNTs. Based on experimental data and it's fitting to the single diode model, we propose that S-SWNT improve the transport and extraction of photogenerated charges within the solar cell device. [ABSTRACT FROM AUTHOR]

Highly transparent zinc oxide (ZnO) nanowire networks have been used as the active material in thin film transistors (TFTs) and complementary inverter devices. A systematic study on a range of networks of variable density and TFT channel length was performed. ZnO nanowire networks provide a less lithographically intense alternative to individual nanowire devices, are always semiconducting, and yield significantly higher mobilites than those achieved from currently used amorphous Si and organic TFTs. These results suggest that ZnO nanowire networks could be ideal for inexpensive large area electronics. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) nanowires (NWs) grown on carbon fibers using a vapor transport and condensation approach are used as the cathode of a photoelectrochemical cell. The carbon fibers were obtained by electrospray deposition and take the form of a flexible carbon fabric. The ZnO NW on carbon fiber anode is combined with a “black dye” photoabsorber, an electrolyte, and a platinum (Pt) counterelectrode to complete the cell. The results show that ZnO NW and carbon fibers can be used for photoinduced charge separation/charge transport and current collection, respectively, in a photoelectrochemical cell. [ABSTRACT FROM AUTHOR]