Thermal Energy Transport across Hard–Soft Interfaces

Interfacial thermal transport across hard–soft interfaces is of critical importance to a wide variety of energy applications, ranging from composite materials, batteries, thermoelectrics, and photonic crystals to solar–thermal phase transition. In this Perspective, we discuss major experimental and simulation tools used to study such interfacial thermal transport and summarize some new understanding attained. Most studies focus on the interfacial bonding effect, and the underlying relation between bond strength and thermal transport was recently understood from the molecular level: stronger bonds attract soft molecules closer to the hard surface, which leads to more efficient energy communication across the interface. Recent studies have also demonstrated that vibrational spectral coupling is another important factor that influences thermal transport across hard–soft interfaces, a factor that has long been underappreciated for such interfaces. Despite the progress in this field, more research is needed to more deeply understand the physics and transfer the fundamental understanding into rational material design strategies.