Direct Joule-Heated Non-Equilibrium Synthesis Enables High Performing Thermoelectrics

Abstract

High-throughput synthesis of bulk inorganic materials is crucial for accelerating functional materials discovery but is hindered by slow, energy-intensive solid-state methods. We introduce Direct Joule-Heated Synthesis (DJS), a rapid, single-step and scalable solid-state synthesis technique achieving a $10^5$-fold speedup and 20,000x energy efficiency improvement over conventional synthesis. DJS enables the synthesis of dense, bulk chalcogenides ($\mathrm{B}{\mathrm{i}}_{0.5}\mathrm{S}{\mathrm{b}}_{1.5}\mathrm{T}{\mathrm{e}}_3$, $\mathrm{AgSbT}{\mathrm{e}}_2$), achieving a zT of 2.3 at 573 K in optimally Cd/Se co-doped $\mathrm{AgSbT}{\mathrm{e}}_2$, one of the highest for polycrystalline materials at this temperature. DJS enables optimal co-doping and rapid, non-equilibrium solidification, producing lamellar microstructures, interfacial regions, and cation-ordered nanodomains that scatter all-scale phonons, achieving ultralow lattice thermal conductivity (~0.2 $W{m}^{-1}{K}^{-1}$ at 573 K). DJS establishes a new benchmark for scalable and fast synthesis, accelerating functional material discovery.