Thermoelectric properties of Copper Benzenehexathiol*

Copper benzenehexathiol (CuBHT) is an electrically conductive, two-dimensional (2D) metal-organic framework (MOF). It has a potential to be a new class of organic thermoelectric material because of its high electrical conductivity and low thermal conductivity arising from periodic nano-sized pores [1,2]. We measured the thermal conductivity, electrical conductivity, and Seebeck coefficient of thin flakes of Cu-BHT in a mesoscopic device scale. Our measurement of thermal conductivity shows that the phonon mean free path is determined by pore separations even at room temperature, and the temperature dependence of electrical conductivity shows a wide range of variations due to the highly anisotropic connectivity of the 2D CuBHT domains, giving an independent tunability of σ. The thermoelectric figure of merit, ZT, a measure of the efficiency of the energy conversion from heat to electricity, is found to be relatively small as compared with Bi₂Te₃ but is still one of the highest values for MOFs [2].

[1] X. Huang et al. Nat. Commun. 6, 7408 (2015)
[2] L. Sun et al. Joule 1, 168 (2017)