Topic

Investigation of light-induced conductivity switching in photoexcitable molecular wires using STM-BJ methods 

Since the idea that molecules could potentially be used in electrical circuits was proposed by Aviram and Ratner in 1974,[1] research in the field of so-called “molecular electronics” has remained a subject of intensive investigation. Over time, the field has branched into various sub-disciplines focusing on different applications,[2] including charge transport,[3] optoelectronics,[4] and molecular switches.[5] However, a fundamental challenge in ongoing research remains the poor reproducibility, which stems from the dynamic nature of molecules. Various degrees of freedom in molecular rotations, vibrations, and electronic structure contribute to this problem, as do interactions between the molecules and their surrounding environment.[6,7]

To study molecules in an isolated environment, scanning tunneling microscopy (STM) is a widely applied method.[7,8] STM allows for molecular-resolution imaging of the environment surrounding the studied molecules, while simultaneously enabling the probing of electronic properties at the single-molecule level. 

The objective my work is to measure the conductance of molecular wires containing dye units as part of their chemical structure using STM-break junction (BJ) experiments inside a low temperature- (LT-) STM. Furthermore, conductance switching behavior under visible light illumination shall be investigated for these wires.

 

References

[1] A. Aviram, M. A. Ratner, Chemical Physics Letters 1974, 29, 277–283, issn: 00092614, DOI 10.1016/0009-2614(74)85031-1.
[2] S. V. Aradhya, L. Venkataraman, Nature Nanotechnology 2013, 8, 399–410, issn: 17483395, DOI 10.1038/nnano.2013.91.
[3] J. Jang, H. J. Yoon, Journal of the American Chemical Society 2024, 146, 32206– 32221, issn: 0002-7863, DOI 10.1021/jacs.4c11431.
[4] P. Li et al., Reports on Progress in Physics 2022, 85, 086401, issn: 0034-4885, DOI 10.1088/1361-6633/ac7401.
[5] X. Xu, C. Gao, R. Emusani, C. Jia, D. Xiang, Advanced Science 2024, 11, DOI 10.1002/advs.202400877, issn: 2198-3844.
[6] M. Galperin, A. Nitzan, Molecular optoelectronics: The interaction of molecular conduction junctions with light, 2012, DOI 10.1039/c2cp40636e.
[7] W. Xu, R. Li, C. Wang, J. Zhong, J. Liu, W. Hong, Nano Research 2022, 15, 5726–5745, issn: 1998-0124, DOI 10.1007/s12274-022-4102-3.
[8] K. Kuhnke, C. Große, P. Merino, K. Kern, Chemical Reviews 2017, 117, 5174–5222, issn: 0009-2665, DOI 10.1021/acs.chemrev.6b00645.

Poster Presentations

Y. M. Altmann, G. Grunewald, R. Faust, R. Matzdorf
„Effects of functional groups in molecular wires for gas phase deposition“, CINSaT spring colloquium, Friedrichroda, März 13 - 14, 2025.

Y. M. Altmann & N. Kubetschek, U. Kürpick, R. Faust, R. Matzdorf
„STM study of surface supported one-dimensional coordination polymers“, CINSaT autumn colloquium, Kassel, November 6, 2024.

Y. M. Altmann, U. Kürpick, R. Faust, R. Matzdorf
„Break junction measurements of small conductive molecules“, CINSaT spring colloquium, Paderborn, März 7 – 8, 2024.

Thesis

Y. M. Altmann
„Synthesis and investigation of new phenylene-ethynylene molecular wires regarding suitability for conductivity measurements using STM-break-junction methods”, Master Thesis, University of Kassel, 2024

Y. M. Altmann 
„Aza-BODIPY als Grundgerüst für einen molekularen Draht mit Pyridyl-Ankergruppen“, Bachelorarbeit, Universität Kassel, 2021.

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