Direct measurement of charge transport through helical poly(ethyl propiolate) nanorods wired into gaps in single walled carbon nanotubes

Abstract

We report the direct measurement of electrical transport through rod-like polymer molecules, of poly(ethyl propiolate) (PEP), utilizing single walled carbon nanotubes (SWNTs) as electrodes. The electrical properties of the devices were measured (i) before cutting a SWNT, (ii) when a SWNT was cut and (iii) after PEP deposition into the nanoscale gap in a cut SWNT. The gate-dependent electrical properties showed a reduction in current from I(on) = 2.4 x 10(-7) A for SWNT devices to I(on) = 3.6 x 10(-9) A for PEP bridge devices, both with the ON/OFF ratio of 10(4). Similarly, metallic SWNT devices showed a reduction in current from a few hundreds of microA for a SWNT device to a few nA for a PEP-SWNT structure. The current density of a single PEP molecule is 10(5)-10(6) A cm(-2), which is relatively high, indicating that the PEP molecule can carry significant current. Use of SWNT electrodes was seen to be an effective method of contacting PEP nanorods to facilitate electrical measurements.