High performance thermoelectric module through isotype bulk heterojunction engineering of skutterudite materials

We demonstrate filled CoSb3 skutterudite materials with excellent thermoelectric (TE) performance that results in one of the highest reported single stage module efficiency. The improvement in TE material performance was obtained by creating isotype n/n “bulk heterojunction” structure through assembly of novel skutterudite nanocrystals with different Yb-doping content. Combination of significant increase in carrier transport through heterojunction structure and reduction in long-range acoustic phonon transmission by two-phase mixture resulted in enhanced power factor and reduced lattice thermal conductivity. As a result, the figure-of-merit (zT) of heterojunction TE material is improved by more than 35% compared with pristine single homogeneous material. Using these improved TE materials, a high module conversion efficiency of ~9.15% was obtained when operating between 650 °C and 50 °C. This is one of the highest conversion efficiency among the practically measured single stage modules. [Display omitted] •A novel isotype bulk heterojunction (BHJ) structure was designed and achieved.•The stability of BHJ structure was confirmed.•The electrical and thermal transport were optimized simultaneously by BHJ structure.•A high conversion efficiency of 9.15% was achieved under ΔT of 600 °C.