In organic electronics, thermal management is a challenge, as most organic materials conduct heat poorly. As these devices become smaller, thermal transport is increasingly limited by organic-inorganic interfaces, for example that between a metal and a polymer. However, the mechanisms of heat transport at these interfaces are not well understood. In this work, we compare three types of metal-polymer interfaces. Polymethyl methacrylate (PMMA) films of different thicknesses (1-15 nm) were spin-coated on silicon substrates and covered with an 80 nm gold film either directly, or over an interface layer of 2 nm of an adhesion promoting metal-either titanium or nickel. We use the frequency-domain thermoreflectance (FDTR) technique to measure the effective thermal conductivity of the polymer film and then extract the metal-polymer thermal boundary conductance (TBC) with a thermal resistance circuit model. We found that the titanium layer increased the TBC by a factor of 2, from 59 × 106 W·m-2·K-1 to 115 × 106 W·m-2·K-1, while the nickel layer increased TBC to 139 × 106 W·m-2·K-1. These results shed light on possible strategies to improve heat transport in organic electronic systems.
Keywords: adhesion layer; enhancement of thermal boundary conductance; organic electronics; thermal characterization of polymer; thermal conductivity of polymer thin films.