Thermoelectric thin films:Promising strategies and related mechanism on boosting energy conversion performance

Thermoelectrics can be capable of direct and reversible conversion between heat and electricity.Low dimensional thermoelectric materials,especially two dimensional(2D)thin films,have been considered as a breakthrough to decouple the correlations between electronic and thermal transport,contributing to the optimization of thermoelectric performance.During the past few decades,some effective strategies combined with physical concepts like quantum confinement effect,energy filtering effect,band structure tuning and interface engineering are introduced to design high performance thermoelectrics.Having a thorough understanding the underlyingmechanisms is essential to develop thermoelectric materials.Here,our review summarizes the major strategies that can be utilized in thermoelectric thin films,including fabrication of superlattice structure,formation of two-dimensional electron gas(2DEG)system,orientation regulation,strain engineering and magnetic manipulation,from the aspects of deep mechanisms analyses,recent progress and prospects,inspiring significant improvement of thermoelectric properties.