High thermoelectric properties of shear-exfoliation-derived TiS₂-AgSnSe₂ nano-composites via ionized impurity scattering

Liquid-assisted shear exfoliation (LASE) has been proved previously to be a facile approach for micro-texture engineering and TE performance optimization for TiS₂. Furtherly in this work, ionized impurity scattering was introduced by incorporating 4 mol% nano-AgSnSe₂ via LASE. In a specific temperature range of 373–573 K, Seebeck coefficient increased exceptionally in correspondence to an exceptional variation of electrical conductivity with growing temperature, featuring an ionized impurity scattering characteristic and contributing to a record high power factor of 18.2 μW cm⁻¹ K⁻² at 573 K in the LASE-derived nanocomposite. Moreover, lattice thermal conductivity was further reduced because of enhanced phonon scattering due to intercalation, impurity, and enhanced grain boundary density. Ultimately, a highest ZT of 0.78 at 673 K as a renewed record for TiS₂-based materials was achieved, demonstrating an improved effectiveness of the combination of LASE and ionized impurity scattering in optimization of TE performance of TiS₂-like layered TE materials.