Azaindole: A Candidate\nAnchor for Regulating Charge\nPolarity and Inducing Resonance Transmission at the Fermi Level via\nDehydrogenation

Tuning\nthe polarity of charge carriers is essential for designing\nmolecular logic devices in molecular electronics. In this study, the\nelectrical transport properties of a family of azaindole-anchored\nsingle-molecule junctions have been investigated using density functional\ntheory combined with the nonequilibrium Green’s function method.\nThe obtained results reveal that dehydrogenation is an effective method\nfor reversing the polarity of charge carriers. The molecular junctions\nbased on the entire azaindole unit are n-type and contain electrons\nas the principal charge carriers, whereas the dehydrogenated junctions\nare p-type and contain holes as the main carriers. Furthermore, the\nazaindole anchors undergo a transition from an electron-rich to an\nelectron-deficient state due to dehydrogenation, which is the original\ncause of the charge carrier polarity conversion. Dehydrogenated molecular\njunctions also exhibit the Fermi pinning effect and a sharp highest\noccupied molecular orbital (HOMO) resonance peak at the Fermi level.\nIn addition, using Pt electrodes instead of Au electrodes is a means\nof producing a HOMO resonance peak a for azaindole-based molecular\njunctions. This work demonstrates the enormous potential of utilizing\nazaindole-anchored molecular junctions for the implementation of molecular\nlogic and multifunctional molecular devices.