High-performance perovskite thermoelectrics in BaZrS3 via decoupling of charge and heat transport

• • Record-high thermoelectric figure of merit ZT = 0.81 at 750 K in BaZrS3(1−x)Se3x (x=0.25), surpassing all previously reported perovskite materials and wide-band-gap semiconductors (Eg > 1.5 eV). This breakthrough enables waste-heat recovery in mid-temperature (500–750 K) industrial streams where conventional narrow-gap thermoelectrics suffer from thermal degradation. • • Isovalent Se alloying reduces lattice thermal conductivity from 2.07 to 0.99 W m−1 K−1 at room temperature (a 52% reduction) while electron mobility remains nearly unchanged, demonstrating effective decoupling of charge and heat transport. This decoupling is critical for maintaining high power factor while suppressing thermal losses, a key bottleneck in thermoelectric material design. • • The material is composed exclusively of earth-abundant, eco-friendly elements (Ba, Zr, S, Se), offering a sustainable alternative to toxic and scarce heavy-metal tellurides (e.g., Bi2Te3, PbTe) for large-scale thermoelectric applications. • • The synthesis via flux-assisted solid-state method yields single-phase samples with up to 25% Se content (x=0.25), confirming the feasibility of scalable production. The thermal stability up to 750 K ensures operational reliability in practical devices, unlike halide perovskites which decompose above 400 K.