Destructive-quantum-interference suppression in crown ether single molecule junction
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THE EUROPEAN PHYSICAL JOURNAL B
Regular Article
Destructive-quantum-interference suppression in crown ether single molecule junction? Zainelabideen Y. Mijbil a and Haider O. Essa Chemistry and Physiology Department, Veterinary Medicine College, Al-Qasim Green University, Al-Qasim Town, Babylon Province 51013, Iraq
Received 26 November 2019 / Received in final form 10 April 2020 Published online 10 June 2020 c EDP Sciences / Societ`
a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. The electronic transmission coefficient of X-crown ether-Y (X = 3Y ; Y = 4, 5, and 6) have been investigated using density functional theory and Green’s function approximation incorporated with the H¨ uckel method. The results illustrate unexpected role of the oxygen atoms to highly enhance charge transport in the crown ether molecules by moving the destructive quantum interferences (QI) close to the Fermi level. Such slight shifting creates a beneficial peak-valley pattern in the transmission spectra that facilitates the ON/OFF variation. Moreover, the length of the crown ether rings offers an insignificant impact on electronic transmission. Hence, we believe that these findings would deepen our understanding of QI patterns and exploit crown ether molecules more practically and efficiently in molecular devices.
1 Introduction In molecular electronics, it is a fundamental task to know and understand the potentials of the prospective systems to build electronic devices like transistors, light-emitting diodes [1], or solar cells. Without any precedent understanding, manufacturing nanoscale devices would be a time-consuming, expensive, and cumbersome procedure. Therefore, theoretical studies are extensively implemented to investigate the electrical conductance of molecular junctions to establish firm foundations for the next coming nanoscale electronic circuits [2–6]. For instance, studies have shown that a junction of benzene molecule confined between two electrodes would offer three conductance states: para (high), meta(low), and ortho (high) [7]. Five-membered molecules like furan show different set of quantum interference rules [5,8,9]; while, cross-conjugated molecules [10], azulene [11], polyaromatic hydrocarbons [12] may or may not acquire an invariant set of charge transport rules. Regarding that, the crown ether (CR) family represents a potential candidate to expand and consolidate our knowledge and applications. Crown ethers are cyclic organic molecules consisting of carbon, oxygen, and hydrogen atoms at the circumference and typically incorporate alkali metal ions to form a so-called metal complex unit. Hence, one expects ?
Supplementary material in the form of one pdf file available from the Journal web page at https://doi.org/10.1140/epjb/e2020-100573-6. a e-mail: [email protected]
that interacting crown ether with organic materials would enhance the electrical conductivity of these organics because of the metal moieties. The reason is that metals have no energy gaps so that e
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