Effective Thermoelectric Switch of Hollow Weakly-Coupled Molecular Junction Based on Twist Angle Effect with Boron-Doping

ABSTRACT

Rational design and adjustment of flexible thermoelectric devices are key points for sustainable and effective thermoelectric conversion, which remains a fundamental challenge due to inherent high thermal conductivity and uncontrolled carrier concentration induced by non-uniform dispersion. Under ingenious combination of weakly-coupled hollow interface and nanotube structure, thermoelectric performance of a dumbbell-like molecular junction comprised of a phenyl-terminated polyyne as central molecule and two semi-infinite 1D single-walled carbon nanotube (SWCNT) as electrodes has been investigated at certain twisted angles (θ). The results indicate that molecule twisting can be reviewed as an effective thermoelectric switch to coordinatingly control electronic and phononic transmission properties simultaneously. Resonance of molecular discrete state and electrode continuous state leads to low thermal conductance, which is sensitively affected by twist angle. Meanwhile, cyclic transformation between p-type and n-type flexible thermoelectrics can be realized by manipulating twist angle in a certain period of rotation. Thermoelectric performance of such a molecular junction can be further improved by boron atom doping at head-to-tail positions, and an excellent figure of merit (ZT = 1.75) is observed near Fermi level under 25° twisted angle. This result inspires an effective strategy to modulate and control thermoelectric conversion, which will greatly broaden applications in thermoelectric twistronics.

KEYWORDS:

• thermoelectric performance
• hollow weakly-coupled interface
• twist angle
• resonance transmission interference
• first-principle calculation

Acknowledgments

The authors wish to acknowledge the support of National Natural Science Foundation of China (NSFC No. 12164046). This work is partly supported by Hunan key laboratory of super micro-structure and ultrafast process.

Disclosure statement

The author declares that there is no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15567265.2023.2252884

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [12164046].