Energy-filtering-induced high power factor in PbS-nanoparticles-embedded TiS₂

We report on a greatly enhanced power factor for 1%PbS-nanoparticle-embedded TiS₂ bulk ceramic, about 1 mW/(mK²) at 300 K and 1.23 mW/(mK²) in a wide temperature range of 573 ∼ 673 K, of which the latter is among the highest so far for TiS₂-based thermoelectric materials. Compared to TiS₂, the power factor is increased by ∼110% at 300 K and (50 ∼ 35)% at 573 ∼ 673 K. This enhancement is derived from a large increase in Seebeck coefficient which overwhelmed the modest degradation of electrical conductivity, which should be attributed to energy filtering induced by the band gap offset between TiS₂ and PbS.