Weak interaction engineering on thermal transport in metal-organic semiconductor nanocomposites with self-assembled monolayers

Abstract

The engineering of weak interactions between metals and organic semiconductors is crucial in regulating energy carrier transport within organic semiconductor electronics. In this study, we introduce self-assembled monolayers (SAMs) to improve thermal transport in metal-organic semiconductor nanocomposites. SAM molecules with different terminal groups (-CH3, -COOH, and -C6H5) and chain lengths are utilized to modify the surface of Au nanoparticles with multiple core diameters. The introduction of SAMs significantly boosts the thermal transport of metal-organic semiconductor nanocomposites, which can be attributed to improved vibrational coupling and stronger nonbonding interactions. Furthermore, longer SAM chains broaden the area of van der Waals regions and further strengthen the intermolecular interaction across the interface, reducing the interfacial thermal transport barrier. Additionally, quantum chemistry calculation and evaluations of interfacial adhesion energy indicate that the π-π stacking interaction between TPD and SAM(-C6H5) molecules forms the best interfacial combination of nanoparticles and TPD molecules, resulting the greatest thermal transport characteristics. Finally, free energy calculations demonstrate that the variation of nanoparticle surface topology with the increase of the SAM chain length induces more obvious free energy fluctuation, which leads to tighter connections between TPD and SAM molecules under weak interaction.