“Boosting Thermoelectric Performance in Nanocrystalline Ternary Skutterudite Thin Films through Metallic CoTe2 Integration”
Bhawna Jarwal from Prof. Kuei-Hsien Chen’s group
A novel intergrown Metal-semiconductor nanocomposite structure consisting coherent metallic cobalt telluride (CoTe2) nanograins within a nanocrystalline ternary skutterudite (Co(Ge1.22Sb0.22)Te1.58 or CGST) matrix proven to be effective for improving thermoelectric performance. This unique microstructure is achieved by composition fluctuation-induced phase separation and in situ growth during thermal annealing to seamlessly integrate the metallic phase to enhance the thermoelectric properties of CGST matrix by simultaneously tailoring its thermal and electronic transport characteristics. The distinct band structures of both materials led to the development of an ohmic-type contact characteristic at the interface. The difference in work function of both materials cause a charge spillover from metallic to semiconducting phase, significantly increasing carrier density. However, the aligned and coherent interface have minimal impact on carrier mobility, resulting in a substantial enhancement in electrical conductivity. Additionally, the presence of the metallic CoTe2 phase effectively reduced lattice thermal conductivity by promoting phonon scattering at the interface boundaries. Consequently, the thermoelectric figure of merit (zT) of the CGST-7 wt.% CoTe2 nanocomposite film displayed a twofold improvement (zT ~ 1.30) at 655 K compared to that of pristine CGST. The findings provide valuable insights into the design of advanced thermoelectric materials.
This work has been published in ACS Applied Materials & Interfaces, 2024, 16 (12), 14770-14780
https://pubs.acs.org/doi/epdf/10.1021/acsami.3c17695
