Frank T, Shmueli S, Cohen Jungerman M, Shekhter P, Selzer Y. Large Seebeck Values in Metal-Molecule-Semimetal Junctions Attained by a Gateless Level-Alignment Method.
NANO LETTERS 2023;
23:10473-10479. [PMID:
37930154 DOI:
10.1021/acs.nanolett.3c03188]
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Abstract
Molecular junctions are potentially highly efficient devices for thermal energy harvesting since their transmission properties can be tailored to break electron-hole transport symmetry and consequently yield high Seebeck and Peltier coefficients. Full harnessing of this potential requires, however, a capability to precisely position their Fermi level within the transmission landscape. Currently, with the lack of such a "knob" for two-lead junctions, their thermoelectric performance is too low for applications. Here we report that the requested capability can be realized by using junctions with a semimetal lead and molecules with a tailored effect of their monolayers on the work function of the semimetal. The approach is demonstrated by junctions with monolayers of alkanethiols on bismuth (Bi). Fermi-level tuning enables in this case increasing the Seebeck coefficient by more than 2 orders of magnitude. The underlying mechanism of this capability is discussed, as well as its general applicability.
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