关键词: thermoelectric materials, lattice thermal conductivity, phonon engineering, bulk nanostructures, low-dimensional structures

Abstract: Thermoelectric materials convert heat directly into electricity and are therefore promising for energy harvesting and environmental applications. Ideal high-performance thermoelectrics combine ultralow lattice thermal conductivity, $\kappa_{\rm L}$, with high carrier mobility, a paradigm commonly termed phonon-glass electron-crystal. However, strong coupling between electronic and phononic transport complicates simultaneous optimization of these properties. Because $\kappa_{\rm L}$ is largely independent of electronic transport, targeted suppression of $\kappa_{\rm L}$ is an effective route to partially decouple heat and charge transport. This review summarizes recent advances in reducing $\kappa_{\rm L}$ via two complementary approaches: phonon engineering of bulk nanostructured systems and phonon engineering of low-dimensional materials. In bulk systems, $\kappa_{\rm L}$ may be minimized while retaining high electrical conductivity and maximizing the thermoelectric figure of merit $ZT$ by controlling three fundamental phonon parameters: the volumetric specific heat $c_{\rm v}$, the phonon group velocity $v_{\rm g}$, and the phonon relaxation time $\tau $. Low-dimensional architectures, including superlattices, nanowires, and nanocomposites, supply additional levers to suppress lattice heat transport and to tailor the electronic structure. Integrating multiscale and multimodal phonon-control strategies enables significant reductions in $\kappa_{\rm L}$ without sacrificing electronic performance, thereby advancing the phonon-glass electron-crystal paradigm.

Key words: thermoelectric materials, lattice thermal conductivity, phonon engineering, bulk nanostructures, low-dimensional structures