Thermally-activated charge transport in carbon atom chains
Charge transport through single molecule is at the heart of molecular electronics realizing practical use of rich quantum characteristics of the electrode-molecule-electrode systems. Despite the extensive studies in the past, however, little experimental effort has been paid on the electron transport mechanism at temperature higher than the ambient. In this work, we report on the observation of subtle interplay between electron tunneling and charge hopping in carbon chains connected to two Au electrodes at elevated temperatures. We measured single-molecule conductance of Au-alkanedithiols-Au molecular junctions at various temperature conditions from 300 K to 420 K in vacuum. The temperature dependence of the conductance suggested substantial roles of superexchange inter-chain charge hopping under elevated temperature for the alkane chains longer than heptane. This finding provides a guide to design functional molecular junctions under practical conditions.