Laser co-ablation of bismuth antimony telluride and diamond-like carbon nanocomposites for enhanced thermoelectric performance

For decades, the V2VI3 compounds, specifically p-type Bi2–x Sb x Te3 and n-type Bi2Te3–x Se x , have remained the cornerstone of commercial thermoelectric solid-state cooling and power generation near room temperature. However, a long-standing problem in V2VI3 thermoelectrics is that n-type Bi2Te3–x Se x is inferior in performance to p-type Bi2–x Sb x Te3 near room temperature, restricting the device efficiency. In this work, we developed high-performance n-type Bi2–x Sb x Te3, a composition long thought to only make good p-type thermoelectrics, to replace the mainstream n-type Bi2Te3–x Se x . The success arises from the synergy of the following mechanisms: (i) the donorlike effect, which produces excessive conduction electrons in Bi2Te3, is compensated by the antisite defects regulated by Sb alloying; (ii) the conduction band degeneracy increases from 2 for Bi2Te3 and Bi2Te3–x Se x to 6 for Bi2–x Sb x Te3, favoring high Seebeck coefficients; and (iii) the larger mass fluctuation yet smaller electronegativity difference and smaller atomic radius difference between Bi and Sb effectively suppresses the lattice thermal conductivity and retains decent carrier mobility. A state-of-the-art zT of 1.0 near room temperature was attained in hot deformed Bi1.5Sb0.5Te3, which is higher than those for most known n-type thermoelectric materials, including commercial Bi2Te3–x Se x ingots and the popular Mg3Sb2. Technically, building both the n-leg and p-leg of a thermoelectric module using similar chemical compositions has key advantages in the mechanical strength and the durability of devices. These results attested to the promise of n-type Bi2–x Sb x Te3 as a replacement of the mainstream n-type Bi2Te3–x Se x near room temperature.

Section: Results and Discussionmentioning

confidence: 99%

n-Bi_2–xSb_xTe₃: A Promising Alternative to Mainstream Thermoelectric Material n-Bi₂Te_3–xSe_x near Room Temperature

Zhou

Meng

et al. 2020

“…Taking into account that the electrical conductivity of inorganic materials will decrease when they are reduced in dimensionality and that the interfacial contact resistance is relatively high when incorporating them into the conductive polymer, many researchers have tried to address it by adding carbon allotropes. ,,− The significant enhancement of the PF was observed because of the enhanced σ caused by the optimized carrier concentration and/or reduced void volume fraction between inorganic particles. Among these carbon allotropes, graphene, a one-atom-thick sp 2 -bonded planar carbon sheet, has frequently been considered as a promising filler to construct better conducting channels because of its higher theoretical surface area, high electrical conductivity, stable thermal properties, and excellent mechanical and chemical properties.…”

Section: Resultsmentioning

confidence: 99%

Flexible n-Type Abundant Chalcopyrite/PEDOT:PSS/Graphene Hybrid Film for Thermoelectric Device Utilizing Low-Grade Heat

Wang

Pang

Guo

et al. 2021

Combining inorganic thermoelectric (TE) materials with conductive polymers is one promising strategy to develop flexible thermoelectric (FTE) films and devices. As most inorganic materials tried up until now in FTE composites are composed of scarce or toxic elements, and n-type FTE materials are particularly desired, we combined the abundant, inexpensive, nontoxic Zndoped chalcopyrite (Cu 1−x Zn x FeS 2 , x = 0.01, 0.02, 0.03) with a flexible electrical network constituted by poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and graphene for n-type FTE films. Hybrid films from the custom design of binary Cu 1−x Zn x FeS 2 /PEDOT:PSS to the optimum design of ternary Cu 0.98 Zn 0.02 FeS 2 /PEDOT:PSS/graphene are characterized. Compared with the binary film, a 4-fold enhancement in electrical conductivity was observed in the ternary film, leading to a maximum power factor of ∼ 23.7 μW m −1 K −2 . The optimum ternary film could preserve >80% of the electrical conductivity after 2000 bending cycles, exhibiting an exceptional flexibility due to the network constructed by PEDOT:PSS and graphene. A five-leg thermoelectric prototype made of optimum films generated a voltage of 4.8 mV with a ΔT of 13 °C. Such an evolution of an inexpensive chalcopyrite-based hybrid film with outstanding flexibility exhibits the potential for cost-sensitive FTE applications.

“…Because of its relatively low tuneable thermal conductivity of ∼10 –1 to 0 –2 Wm –1 K –1 , − it may be applied as a potential candidate to suppress the thermal conductivity of the thermoelectric matrix without seriously affecting the overall conductivity. A series of thermoelectric hetero-nanocomposite films consisting of well-aligned oriented Bi–Sb–Te (BST) nanocrystals and randomly dispersed DLC clusters have been demonstrated using dual-beam pulsed laser co-deposition . Thus far, most of the reported heteroadditives have been randomly dispersed in a matrix because of the difficulty of simultaneous introduction, precipitation, or self-assembly of orderly configured nanoscale additives while fabricating both heterobulk and -films.…”

Section: Introductionmentioning

confidence: 99%

Periodic DLC Interlayer-Functionalized Bi–Sb–Te-Based Nanostructures: A Novel Concept for Building Heterogenized Superarchitectures with Enhanced Thermoelectric Performance

Wang

Chen

Giri

et al. 2022

Self Cite

According to the innovative design concept of omnidirectional quasi-order hetero-nanocomposites proposed for potentially realizing high thermoelectric performance, a series of superarchitectures consisting of longitudinally periodic diamond-like carbon (DLC) interlayers in latitudinally well-aligned Bi–Sb–Te (BST)-based nanostructures were successfully demonstrated for the first time using dual-beam pulsed laser deposition. This work confirmed that the periodic appearance of DLC is a practical approach to instantly resetting the BST deposition into another new crystal growth cycle. The optimized Seebeck coefficient of ∼500 μV K–1 and the corresponding power factor of ∼40 μW cm–1 K–2 achieved are comparable to or higher than the reported values for BST or BST-based nanocomposites, which evidently originated from the periodically added DLC, as clarified in the Pisarenko plot. In addition, the DLC additives effectively reduce the thermal transport as qualitatively evidenced by micro-Raman characterizations.