Marcus Theory and Long-Range Activationless Transport in Molecular Junctions.
J Phys Chem Lett
; 15(27): 6996-7002, 2024 Jul 11.
Article
em En
| MEDLINE
| ID: mdl-38949503
ABSTRACT
Intrachain transport in molecular junctions (MJs) longer than 5 nm has been modeled within the theoretical framework of Marcus theory. We show that in oligo(bisthienylbenzene)-based MJs, electronic transport involves polarons, localized on three monomers that are close to 4 nm in length. They hop and tunnel between adjacent localized sites with reorganization energies λ close to 400-600 meV and electronic coupling parameters Hab close to λ/2. As a consequence, the activation energy for intrachain transport, given by the equation ΔG* = (λ/4)(1 - 2Hab/λ)2, is close to zero, and transport along the chain is activationless, in agreement with experimental observation. On the contrary, similar calculations on conjugated oligonaphthalenefluoreneimine wires show that Hab is much less than λ/2 and predict that the activation energies for intrachain hopping between adjacent sites, close to λ/4, are â¼115 meV. This work proposes a new perspective for understanding long-range activationless transport in MJs beyond the tunneling regime.
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MEDLINE
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En
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2024
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Article