The structure of 2D charge transfer salts formed by TCNQ/alkali metal coadsorption on Ag(111)

Blowey, Phil J.; Rochford, Luke A.; Duncan, David A.; Ryan, Paul T. P.; Warr, Daniel; Lee, TL; Costantini, Giovanni; Woodruff, D.P.

doi:10.1016/j.susc.2020.121687

Cited by 2 publications

(2 citation statements)

References 27 publications

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Section: Resultsmentioning

confidence: 55%

“…It is notable, however, that although the Cs atoms are imaged brightly in the STM (Figure 1a), the K atoms are not imaged in this way. This inability to uniquely identify coadsorbed alkali metal adatoms from STM images has also been seen in alkali/TCNQ layers on Ag(111) 64,65 but we infer from the identical arrangement of the TCNQ molecules that this phase has the comparable K(TCNQ) 4 stoichiometry. Two further KTCNQ coadsorption phases were observed with increasing K coverage leading to indicated stoichiometries of K(TCNQ) 2 and KTCNQ, with associated matrices of ( ) S1 summarizes the properties of all four detected coadsorption phases.…”

Section: Experimental Characterization Of Co-adsorptionmentioning

confidence: 52%

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

et al. 2023

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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.

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Section: Resultsmentioning

confidence: 55%

Section: Experimental Characterization Of Co-adsorptionmentioning

confidence: 52%

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

et al. 2023

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Unlocking the Full Redox Capability of Organic Charge‐Transfer Complex in High‐Loading Electrodes for Organic Rechargeable Batteries

Lee,

Kim,

Hong

et al. 2024

Advanced Energy Materials

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Organic charge‐transfer complex (OCTC) comprising redox‐active donor and acceptor molecules is a promising electrode material group, potentially resolving issues of low power and inferior cycle stability of organic electrodes in rechargeable batteries. Strong intermolecular interactions in OCTC such as π–π interaction and hydrogen bonding enable high electronic conductivity and suppress solubility to solvents. However, full redox activities of OCTC have not been achieved yet despite the inherent redox capabilities of respective donor and acceptor molecules. Here, it is revealed that the limited redox activities of OCTC stem from electrolyte‐incorporated complex formation, which weakens the characteristic intermolecular interactions, thereby hindering the redox reaction, particularly in Li‐based electrolytes. It is further shown that tailoring electrolyte types, specifically using Zn‐aqueous electrolytes, can substantially mitigate the complex formation and unlock the four‐electron redox activity of OCTC (phenazine (PNZ)‐7,7,8,8‐tetracyanoquinodimethane (TCNQ), that is, PNZ–TCNQ), with superior cycle stability retaining 88% of maximum capacity over 100 cycles. Surprisingly, the full redox reaction achieves an unprecedentedly high electrode‐level energy density, delivering ≈10 mAh cm−2 of areal capacity (580 µm‐thick electrodes) in Zn‐aqueous batteries. The findings elucidate the complex interplay between organic electrodes and electrolytes in the charge storage mechanism, highlighting the importance of electrolyte design in developing organic electrode materials.

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The structure of 2D charge transfer salts formed by TCNQ/alkali metal coadsorption on Ag(111)

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Cited by 2 publications

References 27 publications

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

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

Unlocking the Full Redox Capability of Organic Charge‐Transfer Complex in High‐Loading Electrodes for Organic Rechargeable Batteries

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