Realization of an Ultrahigh Power Factor and Enhanced Thermoelectric Performance in TiS₂ via Microstructural Texture Engineering

Abstract

Layered 1T-type TiS2 powders were pretreated by an ethanol-based shear pulverization process, which showed outstanding effectiveness in reducing the average grain size and narrowing the size distribution while maintaining high crystallinity and plate-shaped morphology. The resulting bulk ceramics densified by spark plasma sintering possessed a highly (00l)-oriented texture and pronounced anisotropy. They showed a noticeably increased σ and an unaffected S in the in-plane direction due to the increased carrier mobility μ and the constant carrier concentration n, which resulted in a significant enhancement of the in-plane power factor, optimally to an unprecedented high level of 1.6–1.8 mW m–1 K–2 in a range of 323–673 K. Meanwhile, the lattice thermal conductivity was reduced by approximately 20% due to the intensified grain boundary phonon scattering that overwhelmed the effect due to texturing. These effects not only demonstrated the powder shear pulverization pretreatment as a facial and reliable route toward a high-textured TiS2 but also enabled a remarkable increase of ZT record for TiS2-based thermoelectrics (TEs) to approximately 0.7 at 673 K, indicating clearly the significant effect of texture engineering on TE performance.

Thermoelectric Power Generation of TiS2/Organic Hybrid Superlattices Below Room Temperature

“…Seebeck coefficient at 233 K was recorded as −55 µV/K. This value increased to approximately −72 µV/K by heating the film to 323 K. The obtained values are all negative, indicating that this semiconductor has n-type carriers, which is similar to that of TiS 2 reported by many workers [ 35 , 36 , 37 , 38 ]. The calculated power factor, PF, is shown in Figure 5 b.…”

“…Moreover, due to its elegant features such as an attractive structure, lightweight material, cheap chalcogenide, and high electrical conductivity with a semi-metallic behavior [ 31 ], TiS 2 has been employed as a cathode material in rechargeable batteries [ 32 ], electrode materials of pseudocapacitors [ 33 ], and as a sensor material for uric acid determination [ 34 ]. In addition to these applications, the single crystals of TiS 2 were reported to show good TE performance [ 35 , 36 , 37 , 38 ]. It was also involved in nanocomposites [ 39 ] for producing flexible TE materials and devices [ 40 , 41 , 42 ].…”

High-performance flexible thermoelectric modules based on high crystal quality printed TiS2/hexylamine

“…FWHM of B1 is 0.233° while it is 1.25° in the previous study). Finally, very recently, Gu et al [ 36 ] observed a significant increase of the thermoelectric power factor on a mechanically exfoliated and restacked at high-temperature bulk pristine TiS 2 . In this independent study Gu et al also demonstrate that the crystal quality seems to be the key parameter in achieving the high thermoelectric properties in 2D based materials.…”

Synergistically Enhanced Thermoelectric Performance of Cu2SnSe3-Based Composites via Ag Doping Balance

“…2,3 As α, σ, and κ e strongly couple with each other, it is not easy to boost ZT values simply by adjusting any one of these parameters. 4 In order to optimize the electrical properties, a series of carrier engineering strategies, including the band convergence engineering, 5,6 band alignment engineering, 7,8 resonant level effect, 9 spin− orbit effect, 10,11 magnetoelectric effect, 12−14 modulation doping effect, 15,16 texture engineering, 17,18 and so forth, have emerged to improve the power factor. Meanwhile, various phonon engineering approaches have also been employed to lower the lattice thermal conductivity via phonon−liquid effect, 19,20 lattice softening effect, 21,22 hierarchical architecture engineering, 23−25 and so forth.…”

“…The TE performance of a material is gauged by its dimensionless figure-of-merit ZT value, defined as ZT = α 2 σ T /(κ L + κ e ), where α, σ, κ L , κ e , and T are the Seebeck coefficient, electrical conductivity, lattice thermal conductivity, electronic thermal conductivity, and the absolute temperature, respectively. , As α, σ, and κ e strongly couple with each other, it is not easy to boost ZT values simply by adjusting any one of these parameters . In order to optimize the electrical properties, a series of carrier engineering strategies, including the band convergence engineering, , band alignment engineering, , resonant level effect, spin–orbit effect, , magnetoelectric effect, − modulation doping effect, , texture engineering, , and so forth, have emerged to improve the power factor. Meanwhile, various phonon engineering approaches have also been employed to lower the lattice thermal conductivity via phonon–liquid effect, , lattice softening effect, , hierarchical architecture engineering, − and so forth.…”