Polyaniline/single-walled carbon nanotube composite electronic devices

Composites of high molecular weight polyaniline (PANI) and various weight percentages of single-walled carbon nanotubes (SWNT) were fabricated using solution processing. Electrical characteristics of metal-semiconductor (MS) devices fabricated from the PANI/SWNT composites were studied. Current-voltage (I-V) characteristics of these devices indicate a significant increase in current with an increase in carbon nanotube concentration in the composite. The dominant transport mechanisms operating in these devices were investigated by plotting the forward I-V data on a log-log scale, which revealed two power-law regions with different exponents. In the lower voltage range, the exponent is approximately 1, implying that the charge transport mechanism is governed by Ohm's law. The charge transport mechanism in the higher voltage range, where the exponent varies between 1.1 and 1.7, is consistent with space-charge-limited (SCL) emission in the presence of shallow traps. The critical voltage (V-c), which characterizes the onset of SCL conduction, decreases with increasing SWNT concentration. In addition, V-c was observed to increase with temperature. These initial results indicate that with further improvements in material consistency and reduction in defect densities, the polyaniline/single-walled carbon nanotube composite material can be used to fabricate organic electronic devices leading to many useful applications in microelectronics. (C) 2004 Elsevier Ltd. All rights reserved.