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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]

This paper reports on the synthesis of zinc oxide (ZnO nanostructures and examines the performance of nanocomposite thin-film transistors (TFTs fabricated using ZnO dispersed in both n- and p-type polymer host matrices. The ZnO nanostructures considered here comprise nanowires and tetrapods and were synthesized using vapor phase deposition techniques involving the carbothermal reduction of solid-phase zinc-containing compounds. Measurement results of nanocomposite TFTs based on dispersion of ZnO nanorods in an n-type organic semiconductor ([6, 6]-phenvl-C61-butyric acid methyl ester) show electron field-effect mobilities in the range 03-0.6 cm²V-1s-1, representing an approximate enhancement by as much as a factor of 40 from the pristine state. The on/off current ratio of the nanocomposite TFTs approach 106 at saturation with off-currents on the order of 10 pA. The results presented here, although preliminary, show a highly promising enhancement for realization of high-performance solution-processable n-type organic TFTs. [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]