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Curiosity-Driven Molecular Modeling: Shuttlecock-Shaped Molecular Rectifier’s Asymmetric Electron Transport Coupled with Controlled Molecular Motion

Title
Curiosity-Driven Molecular Modeling: Shuttlecock-Shaped Molecular Rectifier’s Asymmetric Electron Transport Coupled with Controlled Molecular Motion
Authors
Jang, Yun Hee
DGIST Authors
Jang, Yun Hee
Issue Date
2019-11-05
Citation
The 5th International Conference on Molecular Simulation (ICMS 2019)
Type
Conference
Abstract
A Langmuir-Blodgett (LB) monolayer of a shuttlecock-shaped asymmetric fullerene derivative on Au(111) exhibits a rectification (i.e., asymmetric I-V curve or ON/OFF switching) under a conducting AFM measurement. Its rectification ratio at high voltage (1.5 V) is an order-of-magnitude higher than at low voltage (1.0 V). Using a multiscale molecular modeling combining molecular dynamics (MD), density functional theory (DFT), and non-equilibrium Green’s-function formalism (NEGF), we identify the origin of such rectification behavior of this plausible molecular diode, which can be a low-energy-consumption alternative of conventional Si-based diodes. The low rectification ratio exhibited at 1.0 V is reproduced by DFT-NEGF calculations on a metal-molecule-metal sandwich-type model device at a standing-up molecular orientation expected for a fresh LB monolayer. It originates from the slight asymmetry in molecular structure, which creates a non-negligible dipole moment. It is, however, insufficient to explain higher rectification ratios observed in experiments performed at 1.5 V. MD simulations of its self-assembled monolayer on Au(111) show that its molecular orientation can switch between standing-up and lying-on-the-side configurations in order to align its molecular dipole moment with the direction of the applied electric field. Indeed, DFT-NEGF calculations considering such field-induced reorientation yield an order-of-magnitude higher rectification ratio, explaining the experimental observation.
URI
http://hdl.handle.net/20.500.11750/14186
Publisher
대한금속·재료학회
Related Researcher
  • Author Jang, Yun Hee CMMM Lab(Curious Minds Molecular Modeling Laboratory)
  • Research Interests Multiscale molecular modeling (quantum mechanics calculation; molecular dynamics simulation) : Supercomputer-assisted molecular-level understanding of materials and their chemistry; which leads to rational design of high-performance organic-inorganic-hybrid materials for clean and renewable energy as well as low-energy-consumption electronic devices
Files:
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Collection:
Department of Energy Science and EngineeringCMMM Lab(Curious Minds Molecular Modeling Laboratory)2. Conference Papers


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