Functional optimization by control of the electronic and structural properties of organic molecules on surfaces studied by scanning tunnelling microscopy

• Applicants: Professor Dr. Saeed Amirjalayer; Professor Dr. Harald Fuchs
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2016 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 332724838

• Final Report Year: 2022

Final Report Abstract

n our joined experimental and theoretical work, we investigated the structural, electronic, and dynamic properties of molecular species at metal surfaces. Both single molecules, complex molecular assemblies as well as functional and dynamic systems were the subject of our research. In this context, we could provide a detailed insight into the impact of metal substrates on the fabricated molecular architectures. Our results emphasize the importance to tune the on-surface confinement by balancing the interaction between functional groups and the metal. By combining scanning probe microscopy with atomistic calculations, we could further show that the variation of the metal substrates leads to the formation of different 2D coordination polymers with different electronic properties. In addition, we utilized our methodology to investigate a new class of ligands to functionalize and even modify the metal surfaces with atomic precision. In particular, our DFT-based calculations could provide a detailed mechanistic insight into these phenomena. To further control the self-assembly of molecular structures, we investigated the potential of using nanostructured surfaces as templates. On the one hand, we analyzed the interaction of single molecules with a metal/metal oxide phase boundary. Here, we could provide a detailed picture of the energetically preferred adsorption site and the charge redistribution, by combining noncontact atomic force microscopy experiments combined with XPS spectroscopy and atomistic calculations. On the other hand, we considered more complex surface structures, by investigating the growth process of molecules on a polymer surface. Our theoretical investigations enabled us to decipher the change of the molecular packing depending on the atomic structure of the polymer. Based on this, the optoelectronic properties are changed. Within our project, we could transfer this fundamental understanding into applications, by using the polymeric surface as a guiding element in optoelectronic devices. These devices showed an unprecedented high charge mobility. Since a pure quantum mechanical representation of these complex and hierarchical structures is too time-demanding, in particular, if dynamic phenomena (such as the growth process of molecular assemblies) are involved, we have extended our theoretical methodology within this project. We have developed a new parametrization protocol for interatomic potentials. We demonstrate the potential of this approach in a proof-of-principle study for a highly dynamic molecular system. Grounded on the results obtained within this project on single molecules and molecular assemblies, future research efforts aim to apply this approach together with our experimental techniques to reveal the correlation of dynamic phenomena with electronic properties of hierarchical molecular assemblies.

Publications

• Surface Polarity and Self-structured Nanogrooves Collaborative Oriented Molecular Packing for High Crystallinity towards Efficient Charge Transport, J. Am. Chem. Soc., 139, 2734 (2017)
  D. Ji, X. Xu, L. Jiang, S. Amirjalayer, L. Jiang, Y. Zhen, Y. Zou, Y. Yao, H. Dong, J. Yu, H. Fuchs, W. Hu
  
• Chemistry of 4-[(4-bromophenyl)ethynyl]-pyridine at metal surfaces studied by STM, Chem. Commun., 54, 9305 (2018)
  J. Ren, E. Larkin, C. Delaney, Y. Song, X. Jin, S. Amirjalayer, A. Bakker, S. Du, H.-Y. Gao, Y.-Y. Zhang, S. M. Draper, H. Fuchs
  
• Site-Specific Adsorption of Aromatic Molecules on a Metal/Metal Oxide Phase Boundary, Nano Lett., 18, 4123 (2018)
  A. Timmer, H. Mönig, M. Uphoff, O. Díaz Arado, S. Amirjalayer, H. Fuchs
  
• Band-like Transport in Small-Molecule Thin Films toward High Mobility and Ultrahigh Detectivity Phototransistor Arrays, Nature Comm., 10, 12 (2019)
  D. Ji, T. Li, J. Liu, S. Amirjalayer, M. Zhong, Z. Zhang, X. Huang, Z. Wei, H. Dong, W. Hu, H. Fuchs
  
• Quinone-Facilitated Coordinated Bipyrene and Polypyrene on Au(111) by Capture of Gold Adatoms, J. Phys. Chem. C, 123, 26, 16281 (2019)
  X. Liu, Y. Du, A. Timmer, H. Mönig, X. Wan, X. Huang, Q. Ji, E. Kan, K. Ariga, J.P. Hill, H. Fuchs, and H. Kong
  
• Elucidating the Impact of Molecular Motors on Their Solvation Environment, J. Phys. Chem. B, 124, 10879 (2020)
  E. Kolodzeiski, S. Amirjalayer
  
• Highly Efficient Charge Transport in a Quasi‐Monolayer Semiconductor on Pure Polymer Dielectric, Adv. Funct. Mater., 1907153 (2020)
  D. Ji, Y. Zou, K. Wu, F. Yang, S. Amirjalayer, L. Li, X. Huang, T. Li, W. Hu, H. Fuchs
  
• Tunable thiolate coordination networks on metal surfaces, ChemNanoMat, 6, 1 (2020)
  X. Meng, E. Kolodzeiski, X. Huang, A. Timmer, B. S. Lammers, H.-Y. Gao, H. Mönig, L, Liu. W. Xu, S. Amirjalayer, D. Zhu, H. Fuchs
  
• Conformational evolution following the sequential molecular dehydrogenation of PMDI on a Cu(111) surface, Nanoscale Adv., 3, 6373 (2021)
  L. Liu, A. Timmer, E. Kolodzeiski, H.-Y. Gao, H. Mönig, H. Klaasen, X. Meng, J. Ren, A. Studer, S. Amirjalayer, H. Fuchs
  
• On-the-Fly Training of Atomistic Potentials for Flexible and Mechanically Interlocked Molecules, J. Chem. Theory Comput. 17, 7010 (2021)
  E. Kolodzeiski, S. Amirjalayer