Rigid adamantane tripod linkage for well-defined conductance of a single-molecule junction

We present a systematic analysis of molecular level alignments and electron transport characteristics based on the non-equilibrium Green's function (NEGF) approach combined with density functional theory (DFT) for phenyl dithiol (PDT) derivatives with two different linkages, simple thiol (ST) and tripod-shaped adamantane trithiol (ATT). The substantial adamantane-metal bonds afford a rigid contact structure and well-defined conductance of a single-molecule junction irrespective of interfacial phenomena, which accordingly allows us to utilize the intrinsic nature of the molecule for designing molecular devices with prescribed transport characteristics. We suggest a feasible application of the ATT linkage embedded single-molecule junction to a molecular transistor based on the practical feature of the ATT linkage, which is the unsusceptible behavior of transmission under the applied bias voltage. The present result may serve as an important reference point for designing molecular devices with prescribed transport properties.