title: Chemical control over the energy-level alignment in a two-terminal junction.
abstract: The energy-level alignment of molecular transistors can be controlled by external gating to move molecular orbitals with respect to the Fermi levels of the source and drain electrodes. Two-terminal molecular tunnelling junctions, however, lack a gate electrode and suffer from Fermi-level pinning, making it difficult to control the energy-level alignment of the system. Here we report an enhancement of 2 orders of magnitude of the tunnelling current in a two-terminal junction via chemical molecular orbital control, changing chemically the molecular component between a stable radical and its non-radical form without altering the supramolecular structure of the junction. Our findings demonstrate that the energy-level alignment in self-assembled monolayer-based junctions can be regulated by purely chemical modifications, which seems an attractive alternative to control the electrical properties of two-terminal junctions.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Li
authors.initials: L
authors.lastname: Yuan
authors.affiliation: Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Franco
authors.affiliation: Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Crivillers
authors.affiliation: Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Mas-Torrent
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Liang
authors.initials: L
authors.lastname: Cao
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: C S Suchand
authors.initials: CSS
authors.lastname: Sangeeth
authors.affiliation: Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain.
authors.forename: Concepció
authors.initials: C
authors.lastname: Rovira
authors.affiliation: Department of Molecular Nanoscience and Organic Materials, Institut de Ciència de Materials de Barcelona (ICMAB-CSIC) and Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Campus de la UAB, Bellaterra 08193, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Veciana
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.|Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546, Singapore.|Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, Singapore 117574, Singapore.
authors.forename: Christian A
authors.initials: CA
authors.lastname: Nijhuis