Investigation of Amperometric Sensing Mechanism in Gold–C₆₀–Gold Molecular Dot

We investigate through simulations the gold–C60–gold molecular junction as a novel single-molecule amperometric gas sensor. We find it promising for NO and NO2 detection in air and at room temperature, with current variations of the order of the microampere, and presenting the potential capability of achieving the single-molecule sensitivity along with selectivity in the presence of common atmospheric gases. Furthermore, and for the first time, we investigate the current modulation mechanism due to target–sensor intermolecular interactions, providing theoretical insights into the functioning and exclusive properties of this novel device. In particular, we show and motivate the peculiar voltage-dependent response of the sensor that we relate to the distinctive mechanism of transport modulation occurring in the presence of a specific target. Finally, we discuss sensing reliability in air and the effects of probable fabrication process variability on sensing performance. Our results motivate future works on molecular dot-based chemical sensors in terms of the sensor–target exclusive interactions and detection principles, oriented to device-level engineering to find optimal operating conditions.