A New Approach to Materials Discovery for Electronic and Thermoelectric Properties of Single-Molecule Junctions

作者：Manrique, David Zsolt^*; Al-Galiby, Qusiy; Hong, Wenjing; Lambert, Colin J.^*

来源：Nano Letters, 2016, 16(2): 1308-1316.

DOI：10.1021/acs.nanolett.5b04715

• Single molecular junction
• quantum circuit
• thermopower
• conductance
• asymmetric and symmetric junctions
• thermoelectricity

We have investigated a large set of symmetric and asymmetric molecules to demonstrate a general rule for molecular-scale quantum transport, which provides a new route to materials design and discovery. The rule states "the conductance G(XBY) of an asymmetric molecule is the geometric mean of the conductance of the two symmetric molecules derived from it and the thermopower S-XBY of the asymmetric molecule is the algebraic mean of their thermopowers". The studied molecules have a structure X-B-Y, where B is the backbone of the molecule, while X and Y are anchor groups, which bind the molecule to metallic electrodes. When applied to experimentally measured histograms of conductance and thermopower, the rules apply to the statistically most probable values. We investigated molecules with anchors chosen from the following family: cyano, pyridl, dihydrobenzothiol, amine and thiol. For the backbones B, we tested 14 different structures. We found that the formulas (G(XBY))(2) = G(XBX)*G(YBY) and S-XBY = (S-XBX + S-YBY)/2 were satisfied in the large majority of the cases, provided the Fermi energy is located within the HOMO-LUMO gap of the molecules. The circuit rules imply that if measurements are performed on molecules with n(A) different anchors and n(B) different backbones, then properties of n(A)(n(A) + 1) n(B)/2 molecules can be predicted. So for example, in the case of 20 backbones and 10 anchors, 30 measurements (or reliable calculations) can provide a near quantitative estimate for 1070 measurements of other molecules, at no extra cost.

• 出版日期2016-2
• 单位厦门大学