title: Ordinary and Hot Electroluminescence from Single-Molecule Devices: Controlling the Emission Color by Chemical Engineering.
abstract: Single-molecule junctions specifically designed for their optical properties are operated as light-emitting devices using a cryogenic scanning tunneling microscope. They are composed of an emitting unit-a molecular chromophore-suspended between a Au(111) surface and the tip of the microscope by organic linkers. Tunneling electrons flowing through these junctions generate a narrow-line emission of light whose color is controlled by carefully selecting the chemical structure of the emitting unit. Besides the main emission line, red and blue-shifted vibronic features of low intensity are also detected. While the red-shifted features provide a spectroscopic fingerprint of the emitting unit, the blue-shifted ones are interpreted in terms of hot luminescence from vibrationally excited states of the molecule.
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS-Université de Strasbourg), 67034 Strasbourg, France.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Chong
authors.affiliation: Institut Parisien de Chimie Moléculaire, Sorbonne Universités, UPMC Univ Paris 06, CNRS , 75005 Paris, France.
authors.forename: Lydia
authors.initials: L
authors.lastname: Sosa-Vargas
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS-Université de Strasbourg), 67034 Strasbourg, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Bulou
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS-Université de Strasbourg), 67034 Strasbourg, France.
authors.forename: Alex
authors.initials: A
authors.lastname: Boeglin
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS-Université de Strasbourg), 67034 Strasbourg, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Scheurer
authors.affiliation: Institut Parisien de Chimie Moléculaire, Sorbonne Universités, UPMC Univ Paris 06, CNRS , 75005 Paris, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Mathevet
authors.affiliation: Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 (CNRS-Université de Strasbourg), 67034 Strasbourg, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Schull
keywords: STM-induced light emission; Scanning tunneling microscopy; low-temperature fluorescence; porphyrin-based emitters; single-molecule spectroscopy; vibronic microscopy