Liao's main research interest is in nanoscale energy transport and its application to sustainable energy technologies. Specifically, his research aims to understand the transport and interaction processes of fundamental energy carriers, such as electrons, phonons, photons and magnons, at the smallest length and time scales, and then use the knowledge to develop more efficient clean energy devices, e.g. thermoelectric modules and photovoltaic cells. Current projects include first-principles and multiscale simulation of energy carrier transport, visualization of photophysics in space and time with scanning ultrafast electron microscopy, ultrafast optical techniques for thermal and thermoelectric characterization, and applied clean energy devices and systems.