Dual optimization strategy to improve microwave driven AgInSe2-based thermoelectric materials

AgInSe2 has been regarded as a highly promising candidate for mid-temperature thermoelectricapplications, primarily attributed to its intrinsic low lattice thermal conductivity and superiorenvironmental friendliness. To enhance its practical applicability and address the critical limitationsof inherently low electrical conductivity and suboptimal power factor, this study adopted the rapidmicrowave melting to synthesis the material, and integrated the dual optimization strategies of Fedoping and carbon nanotubes (CNTs) compositing to synergistically regulate the thermoelectrictransport properties. Systematic investigations revealed that Fe doping effectively optimized thecarrier concentration of the material to 2.96×1019 cm–3, laying a foundational framework for furtheroptimization. The incorporation of CNTs not only furnished high mobility pathways for electrontransport but also introduced more interface phonon scattering centers, synergistically decreasingthermal conductivity while enhancing electrical conductivity. Notably, the AgIn0.99Fe0.01Se2-0.6wt% CNTs sample achieved a peak thermoelectric figure of merit (ZT) of ~ 0.55 at 780 K,representing a 1.5-times enhancement compared to the pristine material. Additionally, the Vickershardness of the optimized composite was improved by 32%, realizing the concurrent optimizationof both thermoelectric transport properties and mechanical performance. By orchestrating a dual-optimization paradigm, this investigation elucidates the microscopic mechanisms governingthermoelectric transport properties enhancement in intrinsically low-carrier AgInSe2, therebyfurnishing a transferable roadmap for elevating environmentally benign energy-harvestingtechnologies toward practical deployment.