  A thorough understanding of the microscopic picture of heat conduction in
solids is critical to a broad range of applications, from thermal management of
microelectronics to more efficient thermoelectric materials. The transport
properties of phonons, the major microscopic heat carriers in semiconductors
and insulators, particularly their scattering mechanisms, have been a central
theme in microscale heat conduction research. In the past two decades,
significant advancements have been made in computational and experimental
efforts to probe phonon-phonon, phonon-impurity, and phonon-boundary scattering
channels in detail. In contrast, electron-phonon scatterings were long thought
to have negligible effects on thermal transport in most materials under ambient
conditions. This article reviews the recent progress in first-principles
computations and experimental methods that show clear evidence for a strong
impact of electron-phonon interaction on phonon transport in a wide variety of
technologically relevant solid-state materials. Under thermal equilibrium
conditions, electron-phonon interactions can modify the total phonon scattering
rates and renormalize the phonon frequency, as determined by the imaginary part
and the real part of the phonon self-energy, respectively. Under nonequilibrium
transport conditions, electron-phonon interactions can affect the coupled
transport of electrons and phonons in the bulk through the "phonon or electron
drag" mechanism as well as the interfacial thermal transport. Based on these
recent results, we evaluate the potential use of electron-phonon interactions
to control thermal transport in solids. We also provide an outlook on future
directions of computational and experimental developments.
