σ-dominated charge transport in sub-nanometer molecular junctions
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σ-dominated charge transport in sub-nanometer molecular junctions. / Hu, Yong; Zhou, Yu; Ye, Jingyao; Yuan, Saisai; Xiao, Zongyuan; Shi, Jia; Yang, Yang; Solomon, Gemma C.; Hong, Wenjing.
In: Fundamental Research, 2024.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - σ-dominated charge transport in sub-nanometer molecular junctions
AU - Hu, Yong
AU - Zhou, Yu
AU - Ye, Jingyao
AU - Yuan, Saisai
AU - Xiao, Zongyuan
AU - Shi, Jia
AU - Yang, Yang
AU - Solomon, Gemma C.
AU - Hong, Wenjing
N1 - Funding Information: This work was supported by the National Natural Science Foundation of China (Grants No. 21722305 , 21673195 , 21973079 , and 21703188 ), the National Key R&D Program of China (Grant No. 2017YFA0204902 ), and the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2020A151511106 ). Publisher Copyright: © 2022
PY - 2024
Y1 - 2024
N2 - Quantum tunneling conductance of molecular junctions originates from the charge transport through the π-orbitals (π-transport) and the σ-orbitals (σ-transport) of the molecules, but the σ-transport can not be observed due to the more rapid decay of the tunneling conductance in the σ-system compared to that in the π-system. Here, we demonstrate that dominant σ-transport can be observed in π-conjugated molecular junctions at the sub-nanometer scale using the scanning tunneling microscope break junction technique (STM-BJ). We have found that the conductance of meta-connected picolinic acid, which mainly occurs by σ-transport, is ∼35 times higher than that of its para-isomer, which is entirely different from what is expected from π-transport through these systems. Flicker noise analysis reveals that the transport through the meta-connection exhibits more through-bond transport than the para-counterpart and density functional theory (DFT) shows that the σ-system provides the dominant transport path. These results reveal that the σ-electrons, rather than the π-electrons, can dominate charge transport through conjugated molecular junctions at the sub-nanometer scale, and this provides a new avenue toward the future miniaturization of molecular devices and materials.
AB - Quantum tunneling conductance of molecular junctions originates from the charge transport through the π-orbitals (π-transport) and the σ-orbitals (σ-transport) of the molecules, but the σ-transport can not be observed due to the more rapid decay of the tunneling conductance in the σ-system compared to that in the π-system. Here, we demonstrate that dominant σ-transport can be observed in π-conjugated molecular junctions at the sub-nanometer scale using the scanning tunneling microscope break junction technique (STM-BJ). We have found that the conductance of meta-connected picolinic acid, which mainly occurs by σ-transport, is ∼35 times higher than that of its para-isomer, which is entirely different from what is expected from π-transport through these systems. Flicker noise analysis reveals that the transport through the meta-connection exhibits more through-bond transport than the para-counterpart and density functional theory (DFT) shows that the σ-system provides the dominant transport path. These results reveal that the σ-electrons, rather than the π-electrons, can dominate charge transport through conjugated molecular junctions at the sub-nanometer scale, and this provides a new avenue toward the future miniaturization of molecular devices and materials.
KW - Device miniaturization
KW - Flicker noise analysis
KW - Scanning tunneling microscope break junction technique
KW - Sub-nanometer molecular junction
KW - Σ-dominated charge transport
U2 - 10.1016/j.fmre.2022.06.021
DO - 10.1016/j.fmre.2022.06.021
M3 - Journal article
AN - SCOPUS:85140324975
JO - Fundamental Research
JF - Fundamental Research
SN - 2667-3258
ER -
ID: 338440880