吳欣潔

Abstract:

The advancement of thermoelectric (TE) materials for sustainable energy conversion requires both structural stability and optimized transport properties. Here, we present neutron-based structural insights combined with phonon engineering and dilute doping strategies to enhance the performance of Zn₄Sb₃ and Bi₂Te₃. For Zn₄Sb₃, neutron diffraction and electron microscopy reveal that dilute Ga substitution suppresses Zn-ion mobility and introduces nanoscale moiré fringes, which scatter a broad spectrum of phonons and yield ultralow lattice thermal conductivity (<0.3 W m⁻¹ K⁻¹ at 623 K). The optimized Ga–Zn₄Sb₃ single crystal achieves a peak figure of merit (zT) near 1.0, offering a Pb-free alternative for mid-temperature applications. For Bi₂Te₃, Mg light doping simultaneously enhances carrier concentration and mobility, leading to a twofold increase in power factor at room temperature. Suppressed bipolar conduction further reduces thermal conductivity at high temperature, enabling a maximum zT of ~1.64 at 300 K and an average zT above 1.0 across 300–550 K. Device-level validation demonstrates an output power of 22 mW and ~3.3% efficiency at ΔT = 150 K. These findings highlight the critical role of neutron-guided defect engineering in phonon suppression and carrier optimization, providing a pathway toward environmentally sustainable thermoelectric modules.

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