Donor–acceptor co-adsorption ratio controls the structure and electronic properties of two-dimensional alkali–organic networks on Ag(100)

DOI: 10.1021/acs.jpcc.2c08688

Authors: B. Sohail (University of Warwick) , P. J. Blowey (Diamond Light Source, University of Warwick) , L. A. Rochford (University of Birmingham) , P. T. P. Ryan (Diamond Light Source) , D. A. Duncan (Diamond Light Source) , T.-L. Lee (Diamond Light Source) , P. Starrs (Diamond Light Source; University of St. Andrews) , G. Costantini (University of Warwick; University of Birmingham) , D. Phil Woodruff (University of Warwick) , R. J. Maurer (University of Warwick)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: The Journal Of Physical Chemistry C

State: Published (Approved)
Published: January 2023
Diamond Proposal Number(s): 17261 , 20785

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.

Subject Areas: Chemistry, Physics, Materials


Instruments: I11-High Resolution Powder Diffraction

Added On: 29/01/2023 20:31

Discipline Tags:

Surfaces Physics Physical Chemistry Electronics Chemistry Materials Science interfaces and thin films Metal-Organic Frameworks Metallurgy Organometallic Chemistry

Technical Tags:

Diffraction Spectroscopy X-ray Standing Wave (XSW) X-ray Photoelectron Spectroscopy (XPS)