Reducing thermal conductivity in Bi-Se co-doped InTe for next-generation thermoelectric materials

Chalcogenide semiconductors remain a focal point in developing innovative, high-performance materials for energy conversion technologies. Among these, the narrow-band-gap p-type semiconductor InTe has garnered considerable interest due to its potential for thermoelectric applications. In this study, we significantly reduced the denominator of the figure of merit (ZT) by effectively lowering the thermal conductivity (κ) through strategic Bi/Se co-doping in the InTe matrix. Polycrystalline samples of InTe and Bi/Se co-doped InTe were synthesized using an environmentally sustainable solid-state reaction method. The co-doped samples achieved a remarkable minimum total thermal conductivity of 0.16 W/mK at 600 K, a 4.75-fold reduction compared to pristine InTe (0.76 W/mK). The XRD study confirmed phase stability, while FESEM and EDS analyses revealed uniform microstructures and effective dopant incorporation. Although carrier mobility decreased due to enhanced scattering at point defects and grain boundaries, pristine InTe achieved the highest ZT (∼0.13) at 600 K due to its superior power factor. This study presents Bi and Se co-doped InTe as a promising next-generation, eco-friendly thermoelectric material. The targeted doping strategy effectively reduces thermal conductivity, laying the groundwork for enhancing thermoelectric performance by optimizing the denominator term of the ZT parameter. While the current work primarily focuses on minimizing thermal conductivity, future efforts will aim at enhancing the power factor through precise control of dopant concentrations, striving to achieve a balanced improvement in thermoelectric efficiency.