Thermal-Driven\nCobalt Intercalation Enhances Thermoelectric <i>ZT</i> of\nn‑Type Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub>

Layered materials have emerged as\nstars in the realm of nanomaterials,\nshowcasing exceptional versatility in various fields. This investigation\nemployed a thermally driven method to intercalate cobalt (Co) into\nthe van der Waals gaps of (CuI)<sub>0.002</sub>Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub> crystals and investigated the mechanism\nby which the intercalated Co enhances the thermoelectric performance\nof the material. Co intercalation decreases the carrier concentration,\nthereby improving the Seebeck coefficient and decreasing both the\nmobility and the electrical conductivity. These effects result in\na significant enhancement of the power factor above 400 K. Theoretical\nelectronic structure calculations provide insights into the role of\nCo in this material. Additionally, the presence of intercalated Co\nsignificantly enhances phonon scattering, thereby boosting the thermoelectric\nfigure-of-merit, <i>ZT</i> to 1.33 at 350 K for 0.17% Co\nintercalation. These findings highlight the potential of Co incorporation\nfor improving the thermoelectric energy efficiency of n-type Bi<sub>2</sub>Te<sub>2.7</sub>Se<sub>0.3</sub>, offering avenues for further\noptimization in thermoelectric applications.