[17a-Z17-1~11] 9.4 Thermoelectric conversion

▲ [17a-Z17-3] Effect of deformation and annealing effect on Thermoelectric Properties of flexible Ag₂S_1-xSe_x (0 < x < 0.55) Material for Energy Applications

〇(PC)Saurabh Singh^1,2, Keisuke Hirata¹, Omprakash Muthusamy¹, Gareoung Kim^1,3, Ying Peng¹, Masahiro Ryu¹, Dogyun Byeon¹, Masaharu Matsunami¹, Tsunehiro Takeuchi^1,2,3 (1.Research Center for Smart Energy Technology, Toyota Technological Institute, Nagoya 468-8511, Japan., 2.CREST, Japan Science and Technology Agency, Tokyo 102-0076, Japan., 3.MIRAI, Japan Science and Technology Agency, Tokyo 102-0076, Japan)

Keywords:Chalcogenides, Thermoelectrics, Device

Recently, Ag₂S is found to be an interesting material, as near room temperature it possesses good flexible properties with very low thermal conductivity (~ 0.5 W/m K) and large Seebeck coefficients (~ –900 mV/K) [3]. However, due to large electrical resistivity (~ 10⁶ mW cm), the value of ZT was found to be very low. To improve the ZT, the partial substitutions of Se, Te at sulfur site are investigated [4,5]. Interestingly, the ductile nature of Ag₂S material found to be excellent with Se substitutions at sulfur site for Ag₂S_1-xSe_x (0 < x < 0.55) compositions, and the maximum ZT of ~0.6 at 300 K is achieved near room temperature [4]. Although the value of ZT is significantly improved, however, the investigations in literature are mainly focused on mechanical properties and their TE properties are studied on bulk samples only [3,5]. In order to know the real performance of flexible, Ag₂S-based thermoelectric devices, it is of great importance to investigate the thermoelectric properties of flexible thin ribbon samples made by mechanical rolling.
In this study, therefore, the TE properties of deformed samples for all the compositions are investigated as function of temperature for both bulk and rolled samples (typical thickness of ~30 mm). The annealing effect treatment on rolled samples is found to be very effective in recovering the value of ZT which is same as obtained for the bulk. This is due to the relaxation of mechanical stress introduced in rolled sample during mechanical deformation.