Current Transmission in KAuBr4 Doped Carbon Nanotube Wiring

Abstract

Chemical doping has been studied extensively in attempts to produce high conductivity carbon nanotube wiring. In the case of KAuBr₄, which has shown excellent performance in experiments, ab initio modeling has shown that the disassociated molecule (potassium and AuBr₄ fragments) produces strong n-type (potassium) and p-type (AuBr₄) doping of the continuous nanotubes. However, dopant performance at the nanotube junctions, an essential feature of CNT based wiring, is not well understood. Recent ab initio modeling of current transmission at the CNT junctions indicates that the potassium atoms induce a moderate level of conventional doping at the junctions, but that AuBr₄ effects on junction current transmission are fundamentally different. As a conventional dopant the AuBr₄ fragments perform poorly, however in an interstitial configuration they produce near perfect current transmission, even at very small nanotube overlaps. Bond current models of the junctions suggest that their ‘perfect’ performance in an interstitial configuration is due to the formation of supramolecular wires, whose noncovalent assembly is assisted by extrusion processes used to fabricate CNT wiring.