Strain‐Mediated Lattice Rotation Design for Enhancing Thermoelectric Performance in Bi₂S₂Se

Abstract

A unique strain-mediated lattice rotation strategy is introduced via nanocompositing to upsurge the optimized limits in the composition-to-structural pathway on rationally engineering the efficient thermoelectric material. In this study, a special lattice rotation via strain engineering is realized to optimize the desired electronic and chemical environment for enhancing thermoelectric properties in n-type Bi 2 S 2 Se. This approach results in a unique transport phenomenon to assist high-energy electrons in transferring through the optimized transport channels, and appropriate structure disparity to significantly localize phonons. As a result, Sb over Cl doping in Bi 2 S 2 Se gently reduces E g and introduces defect states in bandgap with shifting down the Fermi level, thus causing increase in carrier concentration, which contributes to a higher power factor of ≈7.18 µW cm −1 K −2 (at T = 773 K). Besides, a lower thermal conductivity of ≈0.49 W m −1 K −1 is driven through lattice strain and defect engineering. Consequently, an ultra-high ZT max = 1.13 (at T = 773 K) and a high ZT ave = 0.54 (323 K-773 K) are realized. This study not only leads to an extraordinary thermoelectric performance but also reveals a unique paradigm for electron transportation and phonon localization via lattice strain engineering.

Ultralow Thermal Conductivity and Enhanced Thermoelectric Properties Realized in Polycrystalline Bi2S2Se via Carrier and Microstructure Modulation

“…The band structure and density of states (DOS) for both samples are illustrated in Figure . The band gap of pure Bi 2 S 2 Se was found to be approximately 0.96 eV consistent with previous studies. , As shown in Figure a, Bi 2 S 2 Se exhibited a clear energy band merging phenomenon compared to Bi 2 S 3 , along with a slightly reduced band gap, which could explain the higher conductivity of Bi 2 S 2 Se compared to Bi 2 S 3 . Both Bi 2 S 2 Se and Bi 2 S 3 are indirect band gap semiconductors.…”

“…25 Bi 2 S 2 Se possesses the orthorhombic crystal structure with a Pnma space group, which is consistent with that of the Bi 2 S 3 material system. 25,26 The ZT value was successfully optimized from 0.18 to 0.36. In the research conducted by Li et al, it was found that incorporating a small amount of BiI 3 (0.7 vol %) leads to a remarkable decrease of approximately 72% in the lattice thermal conductivity.…”

Unrecoverable lattice rotation governs structural degradation of single-crystalline cathodes

“…From a crystallographic standpoint, lattice rotation refers to displacement of the momentum transfer in the 3D reciprocal space in directions orthogonal to the displacement caused by lattice strain ( 28 ). Lattice rotation is commonly associated with the formation of defects and is prevalent in battery materials as a means to accommodate the heterogeneous electrochemical reactions ( 29 , 30 ). Despite its prevalence, its impact on the structural failure and capacity decay is much less understood compared with that of lattice strain owing to difficulties for its characterization by conventional methods.…”

Low Thermal Conductivity and High Thermoelectric Performance of Nb-Doped Quarternary Mixed Crystal Nb0.05W0.95-xMox(Se1–xSx)2

“…The thermoelectric (TE) approach is now progressively recognized as a significant green energy source. − One of the most important methods for effectively harvesting a massive quantity of waste heat is the primary use of thermoelectric resources, which have the potential to directly convert waste heat energy into electricity. − The dimensionless figure of merit ( ZT = σ S 2 T /κ) determines the efficiency of TE materials, where T , S , σ, and κ represent the absolute temperature, the thermopower, the electrical conductivity, and total thermal conductivity, respectively, whereas, total thermal conductivity (κ) is the combined effect (κ = κ e + κ L ) of the electronic part of thermal conductivity (κ e ) and the lattice thermal conductivity (κ L ). − As a result of the coupling between the TE transport parameters, it is a great challenge to achieve large ZT values. To obtain high ZT , one must simultaneously lower thermal conductivity (κ is also expressed as κ = C P Dd where, C P , D , and d are specific heat, thermal diffusivity, and density, respectively) and enhance power factor PF (PF = σ S 2 ). − However, the PF may be increased by enhancing electrical conductivity (σ), thermopower ( S ), or both through optimization of carrier concentration and band-structure engineering. − The low lattice thermal conductivity can be attained by using various methods, such as nanoincorporations and defect engineering, etc. ,, However, it is difficult to achieve significant PF enhancement and significant reduction of thermal conductivity concurrently due to fundamental coupling within TE parameters (κ, S , and σ) by utilizing a simple approach.…”