Phonon thermal conductivity suppression of bulk silicon nanowire composites for efficient thermoelectric conversion

Chen, Ting-Gang; Yu, Peichen; Chou, Rone-Hwa; Pan, Ci‐Ling

doi:10.1364/oe.18.00a467

Cited by 15 publications

(9 citation statements)

References 21 publications

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“…In this case, the material exhibits the highest porosity (41%), which seems to have the greatest impact on the decrease in the thermal conductivity. Analyses of heat transport in composites and porous thermoelectric materials have been widely reported [62][63][64][65][66]. The commonly applied effective media theory (EMT) [67] is a very useful tool for predicting the value of the thermal or electrical conductivity of a composite using the properties and content of its components.…”

Section: Thermal Conductivitymentioning

confidence: 99%

New synthesis route of highly porous InxCo4Sb12 with strongly reduced thermal conductivity

et al. 2020

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Highly porous, In-filled CoSb 3 skutterudite materials with an attractive thermoelectric figure of merit (ZT * 1) and corresponding dense samples were fabricated through the cost-effective method of reduction in oxides in dry hydrogen and the pulsed electric current sintering (PECS) method, respectively. The reduction process was described in detail using in situ thermogravimetric analysis of Co 2 O 3 , Sb 2 O 3 and In(NO 3) 3 Á5H 2 O separately and in a mixture. Two methods to synthesise the same material were examined: (a) free sintering of an initially reduced powder and (b) PECS. The free-sintered materials with higher porosities (up to * 40%) exhibited lower values of electrical conductivity than the dense PECS samples (porosity up to * 5%), but the benefit of an even sixfold reduction in thermal conductivity resulted in higher ZT values. The theoretical values of thermal conductivity for various effective media models considering randomly oriented spheroid pores are in good agreement with the experimental thermal conductivity data. The assumed distribution and shape of the pores correlated well with the scanning electron microscope analysis of the microstructure. The lowest value of thermal conductivity, equal to 0.5 W/m K, was measured at 523 K for In 0.1 Co 4 Sb 12 with 41% porosity. The highest value of ZT max = 1.0 at 673 K was found for the In 0.2 Co 4 Sb 12 sample in which the porosity was 36%.

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Section: Thermal Conductivitymentioning

confidence: 99%

New synthesis route of highly porous InxCo4Sb12 with strongly reduced thermal conductivity

et al. 2020

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“…The motivation of replicating tremendous successes achieved by using silicon (Si) in the microelectronic industry led researchers to synthesize silicon nanowires and determine their electrical, electronic, optical, and optoelectronic properties [93,94,96]. Along these lines, Si nanowires were also extensively studied for their thermoelectric performances [3,23,[143][144][145][146]. Theoretical studies indicate that thermal conductivities of low diameter (<115 nm) Si nanowires have a quadratic dependence on diameter and surface roughness, which can be written as…”

Section: Elemental Nanowiresmentioning

confidence: 99%

“…Large-area Si nanowire composites, of various nanowire lengths, synthesized via silver-assisted electroless etching exhibit thermal conductivities significantly lower than bulk Si [143]. Composites comprising 310 μm long nanowires have thermal conductivities 43% lower than bulk, while 60 μm and 215 μm long nanowires show a reduction of 17% and 29%, respectively, over bulk [143]. At 200 nm, the nanowires were found to have diameters smaller than the phonon mean free path of ∼250-300 nm [143].…”

Section: Leadmentioning

confidence: 99%

Nanowire-based thermoelectrics

et al. 2017

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Research on thermoelectrics has seen a huge resurgence since the early 1990s. The ability of tuning a material's electrical and thermal transport behavior upon nanostructuring has led to this revival. Nevertheless, thermoelectric performances of nanowires and related materials lag far behind those achieved with thin-film superlattices and quantum dot-based materials. This is despite the fact that nanowires offer many distinct advantages in enhancing the thermoelectric performances of materials. The simplicity of the strategy is the first and foremost advantage. For example, control of the nanowire diameters and their surface roughnesses will aid in enhancing their thermoelectric performances. Another major advantage is the possibility of obtaining high thermoelectric performances using simpler nanowire chemistries (e.g., elemental and binary compound semiconductors), paving the way for the fabrication of thermoelectric modules inexpensively from non-toxic elements. In this context, the topical review provides an overview of the current state of nanowire-based thermoelectrics. It concludes with a discussion of the future vision of nanowire-based thermoelectrics, including the need for developing strategies aimed at the mass production of nanowires and their interface-engineered assembly into devices. This eliminates the need for trial-and-error strategies and complex chemistries for enhancing the thermoelectric performances of materials.

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“…Silicon nanowire forests have been already characterized in the past both embedding them in a polymer [21] and using optical techniques [22,23]. In our work, we characterize devices based on nanowire forests, completed with metal contacts for the electrical and thermal transport, so that they are legs ready to be assembled in a thermoelectric generator.…”

Section: Introductionmentioning

confidence: 99%

Thermal conductivity of silicon nanowire forests

2018

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A large amount of parallel silicon nanowires, placed perpendicularly to a silicon substrate (silicon nanowire forests), has been contacted and assembled in order to fabricate legs of a thermoelectric generator. This paper reports the measurement of the main parameter for thermoelectric applications, which is the thermal conductivity. The reported value, which confirms the strong reduction of the thermal conductivity in nanostructures, is measured on a large amount (> 10 7 ) of parallel nanowires with a diameter variable in the range 60 -120 nm, and takes into account eventual non uniformities which are unavoidable on surfaces of several mm 2 . As silicon nanowire forests are very thin, it has been necessary to develop a suitable measurement apparatus. The fabrication of devices based on silicon nanowire forests, the apparatus and the measurement procedure, as well as the the results, are illustrated and discussed.

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Phonon thermal conductivity suppression of bulk silicon nanowire composites for efficient thermoelectric conversion

Cited by 15 publications

References 21 publications

New synthesis route of highly porous InxCo4Sb12 with strongly reduced thermal conductivity

New synthesis route of highly porous InxCo4Sb12 with strongly reduced thermal conductivity

Nanowire-based thermoelectrics

Thermal conductivity of silicon nanowire forests

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