[8a-E203-1~7] 9.4 Thermoelectric conversion

10:30 AM - 10:45 AM JST(1:30 AM - 1:45 AM UTC)Presentation by Applicant for JSAP Young Scientists Presentation AwardEnglish Presentation

[8a-E203-3] Transition Metal Substitution-Driven Enhancement of Power Factor in Ductile p-Type
Ag_0.8Cu_1.2-xCo_xS_0.1Se_0.1Te_0.8 Thermoelectric Material

〇(P)Suresh Prasanna Chandrasekar^1,2, Taiki Kondo^1,2, Masaharu Matsunami^1,2, Tsunehiro Takeuchi^1,2 (1.Toyota Technological Institute, 2.JST Mirai)

Keywords:

Flexible thermoelectric,P type Ductile,AgCu Chalcogenides

Ductile p-type thermoelectric materials based on the AgCu (S, Se, Te) chalcogenide system have attracted significant attention for flexible energy harvesting applications owing to their intrinsic mechanical ductility, and low lattice thermal conductivity (kappa < 0.60 W m-1 K-1), as well as a competitive near-room-temperature figure of merit. However, the power factor (PF = S^2 * sigma) of this material family remains limited by modest Seebeck coefficients in the 150 - 180 microV K-1 range despite low electrical resistivity. Strategies to decouple Seebeck enhancement from carrier mobility degradation are critically needed.In this work, we investigate the effect of transition metal element (TM) substitution at the Cu site in Ag0.8Cu1.2-xTMxS0.1Se0.1Te0.8 (x = 0.01, 0.02, 0.03) as a novel strategy to enhance thermoelectric performance through resonant-level engineering. TM^alpha+ substituting for Cu+ introduces a partially filled 3d7 configuration that is expected to create a localized impurity level within the valence band near the Fermi energy, thereby distorting the electronic density of states and increasing the Seebeck effective mass without proportionately suppressing carrier mobility. This mechanism is well established in In-doped PbTe and SnTe but unreported in ductile AgCu chalcogenides.Our preliminary results show a systematic, monotonic increase in the Seebeck coefficient from 184 to 197 microV K-1 and in the power factor from 0.232 to 0.346 microW m-1 K-2 as Co content increases from x = 0.01 to 0.03. The electrical resistivity, on the other hand, decreases from 14.6 to 11.2 mOhm cm, consistent with optimization of the hole carrier concentration by Co2+ acting as a p-type acceptor. These results establish Co substitution as a promising and mechanistically distinct route to power factor enhancement for ductile p-type AgCu chalcogenide thermoelectrics.