Interface Tuning of Current-Induced Cooling in Molecular Circuits

• Published in: Journal of physical chemistry. C Vol. 121; no. 2; pp. 1082 - 1088
• Main Authors: Foti, Giuseppe, Vázquez, Héctor
• Format: Journal Article
• Language: English
• Published: American Chemical Society 19.01.2017
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b11955

We study the effect of the atomistic structure of metal–molecule contacts on the current-induced damping and excitation of vibrations in molecular circuits by means of first-principles calculations. We consider a carbene-based molecule bound to Au electrodes via three different tip terminations: a tetramer, a pyramid, and a chainlike structure. The change in the width and position of molecular levels associated with each of these metal–molecule structures under an applied voltage controls the heating and cooling processes. In blunt tips, where the electronic coupling between molecular and Au bulk states is strong, the cooling efficiency decreases as a function of bias which results in the heating of the most active vibrational modes. On the other hand, in chainlike structures where the coupling is weak, the cooling rate has a nonmonotonic behavior as a function of the applied bias and increases sharply beyond a certain voltage. This results in a current-induced cooling at high bias. These findings open the way to the efficient removal of excess heat from the junction through control of the metal–molecule contact structures.