Enhanced Thermoelectric Properties in Bulk Nanowire Heterostructure-Based Nanocomposites through Minority Carrier Blocking

Yang, Haoran; Bahk, Je‐Hyeong; Day, Tristan; Mohammed, Amr; Snyder, G. Jeffrey; Shakouri, Ali; Wu, Yue

doi:10.1021/nl504624r

Cited by 127 publications

(99 citation statements)

References 32 publications

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“…Solution synthesis is a typical bottom-up assembly approach, which is a facile and scalable method to achieve various nanostructures such as nanowires [23], nanobelts [24], nanoplatelets [25][26][27], nanonetworks [28], and even heterostructures [29]. Using these nanostructures as building blocks one can harness great possibilities to achieve various novel nanostructured bulk materials for enhancing the thermoelectric performance.…”

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confidence: 99%

Controlled growth of bismuth antimony telluride Bi Sb2−Te3 nanoplatelets and their bulk thermoelectric nanocomposites

et al. 2015

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Section: Introductionmentioning

confidence: 99%

Controlled growth of bismuth antimony telluride Bi Sb2−Te3 nanoplatelets and their bulk thermoelectric nanocomposites

et al. 2015

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“…[20] The advances include the growth of branched and hyperbranched nanowire structures [21,22], two-nanowireheterostructures-based nanocomposites [23,24], ZnO nanotetrapod bridging networks, [25] and planar nanowire cross-junction architectures. [26] These works have shown the advantages of two-dimensional cross-junction over "bridge" junction.…”

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confidence: 99%

Nano-cross-junction effect on phonon transport in silicon nanowire cages

et al. 2016

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Wave effects of phonons can give rise to controllability of heat conduction beyond that by particle scattering at surfaces and interfaces. In this work, we propose a new class of 3D nanostructure: a silicon-nanowire-cage (SiNWC) structure consisting of silicon nanowires (SiNWs) connected by nano-cross-junctions (NCJs). We perform equilibrium molecular dynamics (MD) simulations, and find an ultralow value of thermal conductivity of SiNWC, 0.173 Wm -1 K -1 , which is one order lower than that of SiNWs.By further modal analysis and atomistic Green's function calculations, we identify that the large reduction is due to significant phonon localization induced by the phonon local resonance and hybridization at the junction part in a wide range of phonon modes. This localization effect does not require the cage to be periodic, unlike the phononic crystals, and can be realized in structures that are easier to synthesize, for instance in a form of randomly oriented SiNWs network.KEYWORDS: Nano-cross-junction, silicon-nanowires-cage, thermal conductivity, local phonon resonance, random network of silicon nanowiresOver the past decades, nanostructures have attracted great attentions due to its unique properties, including the low thermal conductivity. Most-commonly exercised approach is to lower thermal conductivity by phonon scattering at boundaries (surfaces and interfaces) that becomes dominant over intrinsic scattering as the length scales of the nanostructures decreases. Taking silicon nanowires (SiNWs) as a representative material, reduction of thermal conductivity has been realized by enhanced phonon scatterings at surfaces or boundaries due to high surface-to-volume ratio. Another line of effort to further reduce thermal conductivity which works on bulk materials is to utilize wave nature of phonons. Periodic phononic crystals can terminate or inhibit phonon propagation by inducing interference of phonons reflected at boundaries [12][13][14][15]. A challenge here is to ensure the occurrence of wave interferences, which requires strict periodicity of the internal structure with a size on the order of the phonon waves, which is about 1 nm at room temperature. [16] In addition, boundaries of the internal structures need to be smooth enough to specularly reflect phonons. These make production of the phononic crystals by bottom-up synthesis and top-down fabrication extremely challenging. [17] Therefore, there is a strong need for a structure that can give rise to wave effects (interference, localization, and resonance) "locally" so that the periodicity is no longer and planar nanowire cross-junction architectures.[26] These works have shown the advantages of two-dimensional cross-junction over "bridge" junction.In this letter, based on the above bottom-up approach and planar nano-cross-junctions (NCJs), [26] we take a step further and propose a silicon-nanowire-cage (SiNWC) ( Fig. 1(c)) structure consisting of SiNWs ( Fig. 1(a)) and 3D-NCJs ( Fig. 1(b)). Thus, the 1DSiNW is turned into a 3D bulk material as show...

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“…So far, most of the reported Sb 2 Te 3 related materials are p-type semiconductors. [19,[27][28][29][30] For example, Sb 2 Te 3 with 2D nanoplates morphology presents a 30% increase in S (S = 125 µV K −1 ) near room temperature. Typically, Sb 2 Te 3 bulk single crystals stand out for their unique advantages including a high electrical conductivity (σ) around 3-5 × 10 5 S m −1 , and a reasonable thermal conductivity (κ) around 1-6 W m −1 K −1 .…”

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3D Printing of Solution‐Processable 2D Nanoplates and 1D Nanorods for Flexible Thermoelectrics with Ultrahigh Power Factor at Low‐Medium Temperatures

et al. 2019

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graphene, [10] conductive polymer, and hybrids, [11] have the ability to interconvert thermal to electrical energy without moving parts. These f-TEGs can be integrated with portable/wearable electronics and sensors, and enable selfpowered devices. In this context, V 2 -VI 3 metal chalcogenides (Bi 2 Te 3 , Sb 2 Te 3 , and related alloys and compounds) [1,[12][13][14][15][16][17] have attracted particular attention because of their high figure of merit (ZT) near room temperature. [18] For example, p-type Bi 2 Te 3 -Sb 2 Te 3 alloys show high performance near room temperature and benefit considerably from nanostructuring. [19] Similar to Bi 2 Te 3 , Sb 2 Te 3 is also a topological insulator, [20] which leads to a complex, nonparabolic band structure, often highly favorable for thermoelectric (TE) performance. [21] It has an extremely high dielectric constant of ε 0 ≈ 100, favorable for high mobility even with large concentration of defects. [22][23][24] Thus Sb 2 Te 3 is potentially an important TE material, the key challenge being to find methods to control its carrier concentration and to effectively nanostructure the material while maintaining this control. So far, most of the reported Sb 2 Te 3 related materials are p-type semiconductors. This is caused by intrinsic defects including Sb vacancies and antisite defects of Sb atoms on the Te sites (Sb Te ) [25] that occur during normal synthesis procedures. Typically, Sb 2 Te 3 bulk single crystals stand out for their unique advantages including a high electrical conductivity (σ) around 3-5 × 10 5 S m −1 , and a reasonable thermal conductivity (κ) around 1-6 W m −1 K −1 . However, Sb 2 Te 3 also has a less competitive Seebeck coefficient (S) around 83-105 µV K −1 . This is due to its high degenerate hole concentration (n > 10 20 cm −3 ) created by the acceptor states mentioned above, [26] especially Sb Te . Thus key problem is to find ways to control the doping level and thereby reduce the hole concentration and to determine the extent to which this can lead to enhanced S and TE performance. Nanostructuring has been employed to enhance S, and to reduce κ as a result of the increased phonon scattering effect. [19,[27][28][29][30] For example, Sb 2 Te 3 with 2D nanoplates morphology presents a 30% increase in S (S = 125 µV K −1 ) near room temperature. [31] S and ZT enhancement in nanostructured Solution-processable semiconducting 2D nanoplates and 1D nanorods are attractive building blocks for diverse technologies, including thermoelectrics, optoelectronics, and electronics. However, transforming colloidal nanoparticles into high-performance and flexible devices remains a challenge. For example, flexible films prepared by solution-processed semiconducting nanocrystals are typically plagued by poor thermoelectric and electrical transport properties. Here, a highly scalable 3D conformal additive printing approach to directly convert solution-processed 2D nanoplates and 1D nanorods into high-performing flexible devices is reported. The flexible films printed using Sb ...

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Enhanced Thermoelectric Properties in Bulk Nanowire Heterostructure-Based Nanocomposites through Minority Carrier Blocking

Cited by 127 publications

References 32 publications

Controlled growth of bismuth antimony telluride Bi Sb2−Te3 nanoplatelets and their bulk thermoelectric nanocomposites

Controlled growth of bismuth antimony telluride Bi Sb2−Te3 nanoplatelets and their bulk thermoelectric nanocomposites

Nano-cross-junction effect on phonon transport in silicon nanowire cages

3D Printing of Solution‐Processable 2D Nanoplates and 1D Nanorods for Flexible Thermoelectrics with Ultrahigh Power Factor at Low‐Medium Temperatures

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