Donor–Acceptor Co-Adsorption Ratio Controls the Structure and Electronic Properties of Two-Dimensional Alkali–Organic Networks on Ag(100)

Sohail, B.; Blowey, P. J.; Rochford, L. A.; Ryan, P. T.P.; Duncan, D. A.; Lee, T. L.; Starrs, P.; Costantini, G.; Woodruff, D. P.; Maurer, R. J.

Abstract

The results are presented of a detailed combined experimental and theoretical investigation of the influence of coadsorbed electron-donating alkali atoms and the prototypical electron acceptor molecule 7,7,8,8-tetracyanoquinodimethane (TCNQ) on the Ag(100) surface. Several coadsorption phases were characterized by scanning tunneling microscopy, low-energy electron diffraction, and soft X-ray photoelectron spectroscopy. Quantitative structural data were obtained using normal-incidence X-ray standing wave (NIXSW) measurements and compared with the results of density functional theory (DFT) calculations using several different methods of dispersion correction. Generally, good agreement between theory and experiment was achieved for the quantitative structures, albeit with the prediction of the alkali atom heights being challenging for some methods. The adsorption structures depend sensitively on the interplay of molecule–metal charge transfer and long-range dispersion forces, which are controlled by the composition ratio between alkali atoms and TCNQ. The large difference in atomic size between K and Cs has negligible effects on stability, whereas increasing the ratio of K/TCNQ from 1:4 to 1:1 leads to a weakening of molecule–metal interaction strength in favor of stronger ionic bonds within the two-dimensional alkali–organic network. A strong dependence of the work function on the alkali donor–TCNQ acceptor coadsorption ratio is predicted.

Citation

Sohail, B., Blowey, P. J., Rochford, L. A., Ryan, P. T., Duncan, D. A., Lee, T. L., Starrs, P., Costantini, G., Woodruff, D. P., & Maurer, R. J. (2023). Donor–Acceptor Co-Adsorption Ratio Controls the Structure and Electronic Properties of Two-Dimensional Alkali–Organic Networks on Ag(100). Journal of Physical Chemistry C, 127(5), 2716-2727. https://doi.org/10.1021/acs.jpcc.2c08688

• Journal Article Type: Article
• Acceptance Date: Jan 12, 2023
• Online Publication Date: Jan 26, 2023
• Publication Date: Feb 9, 2023
• Deposit Date: Dec 16, 2024
• Publicly Available Date: Dec 18, 2024
• Journal: The Journal of Physical Chemistry C
• Print ISSN: 1932-7447
• Electronic ISSN: 1932-7455
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 127
• Issue: 5
• Pages: 2716-2727
• DOI: https://doi.org/10.1021/acs.jpcc.2c08688
• Public URL: https://nottingham-repository.worktribe.com/output/41932203
• Publisher URL: https://pubs.acs.org/doi/10.1021/acs.jpcc.2c08688