Anharmonicity-induced thermal rectification of a single diblock molecular junction inspired by the Aviram–Ratner diode

Abstract

We examined the design of a unimolecular thermal diode inspired by the concept of the Aviram–Ratner diode and analyzed the anharmonic effects of molecular vibrations in the junction on heat transport. Our central idea involves (i) reconfiguring the electron donor and acceptor into “phonon scatter-rich” (strong anharmonicity) and “phonon scatter-deficient” (weak anharmonicity) moieties and (ii) using hydrogen bonds as thermal spacers to prevent nonlocal anharmonic effects on the thermal transport channel. To evaluate the effects of anharmonic interactions, we developed a fictitious electrode model combined with nonequilibrium Green's function theory and then performed thermal transport calculations. Our results indicate that hydrogen bonds are very promising for constructing thermal molecular device materials. Reducing the thermal gradient and mitigating inelastic phonon scattering effects at the interface are critical for increasing the rectification ratio in single molecular junctions.