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Molecular Junctions: Control of the Energy Gap Achieved by a Pinning Effect

Journal Article · · Journal of Physical Chemistry. C
Single-molecule junctions are the constitutive components of molecular electronics circuits. For any potential application, the energy gap in the junction, i.e., the accumulated energy difference between the electrode Fermi level and the two frontier energy levels of the molecule, is a key property. In this study, using the nonequilibrium Green’s function coupled to the density functional theory framework (NEGF-DFT) method, we show that the gap of the molecule inserted between electrodes can differ largely from the gap of the same molecule, at the isolated level. It can be widely compressed by tuning the alignment mechanism at each metal/molecule interface. In the context of molecular rectification, we show that this mechanism relates to the pinning effect. We discuss the different parameters affecting the compression of the gap and its efficiency. Interestingly, we find that the structure both of the molecule and of the anchoring group plays an important role. Finally, we investigate the evolution of these features out-of-equilibrium.
Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Center for Bio-Inspired Energy Science (CBES)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
SC0000989
OSTI ID:
1388636
Journal Information:
Journal of Physical Chemistry. C, Journal Name: Journal of Physical Chemistry. C Journal Issue: 5 Vol. 121; ISSN 1932-7447
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English

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Impact of offset energies on the yield of interfacial charge separation in molecular photocells journal August 2018