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Efficient thermoelectric energy conversion on quasi-localized electron states in diameter modulated nanowires.

Zianni X - Nanoscale Res Lett (2011)

Bottom Line: It is known that the thermoelectric efficiency of nanowires increases when their diameter decreases.We showed that the electron thermoelectric properties depend strongly on the geometry of the diameter modulation.It is demonstrated that quasi-localized states can be formed that are prosperous for efficient thermoelectric energy conversion.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Applied Sciences, Technological Institution of Chalkida, Psachna, 34400 Evia, Greece. xzianni@teihal.gr.

ABSTRACT
It is known that the thermoelectric efficiency of nanowires increases when their diameter decreases. Recently, we proposed that increase of the thermoelectric efficiency could be achieved by modulating the diameter of the nanowires. We showed that the electron thermoelectric properties depend strongly on the geometry of the diameter modulation. Moreover, it has been shown by another group that the phonon conductivity decreases in nanowires when they are modulated by dots. Here, the thermoelectric efficiency of diameter modulated nanowires is estimated, in the ballistic regime, by taking into account the electron and phonon transmission properties. It is demonstrated that quasi-localized states can be formed that are prosperous for efficient thermoelectric energy conversion.

No MeSH data available.


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ZT0 versus EF, at T = 10 K, for nanowires modulated by one dot (red), three dots (blue) and five dots (dark green).
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Figure 6: ZT0 versus EF, at T = 10 K, for nanowires modulated by one dot (red), three dots (blue) and five dots (dark green).

Mentions: At NB, ZT0 increases when more modulating units are added (Figure 6) because a narrow band with sharper transmission thresholds is formed. This can be seen by comparing T(E) for a single dot and for a finite superlattice of three dots (Figure 2b). It should be noted that the formation of the transmission band edges is completed after a small number of periods and adding more dots does not result in any further increase in ZT0. It should, though, be emphasized that adding more modulating units could result in increase in ZT (Equation 7) due to decreased κph. Phonon conductance decreases due to additional phonon scattering when additional inhomogeneities are introduced in a nanowire.


Efficient thermoelectric energy conversion on quasi-localized electron states in diameter modulated nanowires.

Zianni X - Nanoscale Res Lett (2011)

ZT0 versus EF, at T = 10 K, for nanowires modulated by one dot (red), three dots (blue) and five dots (dark green).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211351&req=5

Figure 6: ZT0 versus EF, at T = 10 K, for nanowires modulated by one dot (red), three dots (blue) and five dots (dark green).
Mentions: At NB, ZT0 increases when more modulating units are added (Figure 6) because a narrow band with sharper transmission thresholds is formed. This can be seen by comparing T(E) for a single dot and for a finite superlattice of three dots (Figure 2b). It should be noted that the formation of the transmission band edges is completed after a small number of periods and adding more dots does not result in any further increase in ZT0. It should, though, be emphasized that adding more modulating units could result in increase in ZT (Equation 7) due to decreased κph. Phonon conductance decreases due to additional phonon scattering when additional inhomogeneities are introduced in a nanowire.

Bottom Line: It is known that the thermoelectric efficiency of nanowires increases when their diameter decreases.We showed that the electron thermoelectric properties depend strongly on the geometry of the diameter modulation.It is demonstrated that quasi-localized states can be formed that are prosperous for efficient thermoelectric energy conversion.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Applied Sciences, Technological Institution of Chalkida, Psachna, 34400 Evia, Greece. xzianni@teihal.gr.

ABSTRACT
It is known that the thermoelectric efficiency of nanowires increases when their diameter decreases. Recently, we proposed that increase of the thermoelectric efficiency could be achieved by modulating the diameter of the nanowires. We showed that the electron thermoelectric properties depend strongly on the geometry of the diameter modulation. Moreover, it has been shown by another group that the phonon conductivity decreases in nanowires when they are modulated by dots. Here, the thermoelectric efficiency of diameter modulated nanowires is estimated, in the ballistic regime, by taking into account the electron and phonon transmission properties. It is demonstrated that quasi-localized states can be formed that are prosperous for efficient thermoelectric energy conversion.

No MeSH data available.


Related in: MedlinePlus