Effect of Increasing Donor Units in Dn–σ–A (n = 1, 2, …5) Type Single-Molecule Diodes Containing Oligomers of 3,4-Ethylenedioxythiophene as Electron Donor: A DFT Study

• Published in: Journal of electronic materials 2025, Vol.54 (1), p.91-102
• Main Authors: Rasheed, Tabish, Angelo, Sandra Winnie, Raghav, Anubhav
• Format: Article
• Language: English
• Subjects: 28th International Conference on Nuclear Tracks and Radiation Measurements; Characterization and Evaluation of Materials; Chemical bonds; Chemistry and Materials Science; Density functional theory; Dipole moments; Electric fields; Electronic circuits; Electronics and Microelectronics; Electrons; Energy Materials; Energy Storage; Instrumentation; Materials Science; Molecular electronics; Optical and Electronic Materials; Organic chemistry; Organic compounds; Quantum chemistry; Solid State Physics; Structural design; Structural models
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-024-11483-1

The field of molecular electronics focuses mainly on the development of novel organic molecules that have the ability to achieve certain specific electronic functionalities due to their unique structural design and properties. One of the most exciting applications of this discipline is the organic single-molecule diode (OSMD), which can deliver efficient current rectification in electronic circuits displaying characteristics identical to those of silicon-based conventional inorganic diodes. The present study showcases newly designed organic molecular systems (OMSs) which can function as OSMDs. The general design of subject OMSs is based on the D n – σ –A ( n  = 1, 2, …5) structural model, which adopts the OSMD scheme proposed by Aviram and Ratner in 1974. In these OMSs, D n , σ , and A denote oligomeric electron donor, σ -bridge, and electron acceptor units, respectively. n represents the number of 3,4-ethylenedioxythiophene compounds which are joined together to form the oligomeric electron donor unit. The electron donor and acceptor moieties are organic compounds which have an electron-donating and electron-accepting nature, respectively. The σ -bridge corresponds to a σ -bonded organic compound that separates D n and A units. The properties of all subject OMSs were simulated using Gaussian 16W quantum chemistry software. Calculations were conducted using density functional theory and the B3LYP hybrid functional along with the 6-311G(d,p) basis set. Detailed investigations were carried out to determine whether subject OMSs have the ability to function as OSMDs. Forward and reverse bias characteristics due to the simulated application of an external electric field on subject OMSs were probed using data obtained for frontier orbitals, dipole moments, and natural bond orbital charges. Also, the effect of an increasing number of donor units was systematically studied by comparative analysis. Molecular electrostatic potential maps were developed for subject OMSs to determine the electron-donating capability of different donor units. Overall, a general trend of increasing efficiency of rectification was observed with an increasing number of donor units in subject OMSs. Graphical Abstract