Assembling π‑Conjugated Molecules with
Negative Gaussian Curvature for Efficient Carbon-Based Metal-Free
Thermoelectric Material
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Abstract
The development of
efficient, lightweight, cost-effective, and
environmentally friendly thermoelectric materials is critical for
energy conversion devices. However, none of the existing thermoelectric
materials satisfy these requirements. Herein, we predict a novel carbon-based
metal-free thermoelectric material denoted as bct-C<sub>80</sub>S<sub>16</sub> that is composed of a π-conjugated saddle-shaped molecular
unit with a negative Gaussian curvature, leading to a low lattice
thermal conductivity while maintaining a high charge mobility. The
resulting peak figure of merit (<i>ZT</i>) of 2.41 at 1000
K is much larger than those of conventional Bi- and Pb-based thermoelectric
materials. Additionally, bct-C<sub>80</sub>S<sub>16</sub> is highly
porous and light, with a mass density of 1.11 g/cm<sup>3</sup>. Such
a high thermoelectric performance and low mass density would make
this metal-free semiconducting material promising for practical applications
in space-based technologies