PT  - JOURNAL ARTICLE
AU  - Doppagne, Benjamin
AU  - Chong, Michael C.
AU  - Bulou, Hervé
AU  - Boeglin, Alex
AU  - Scheurer, Fabrice
AU  - Schull, Guillaume
TI  - Electrofluorochromism at the single-molecule level
AID  - 10.1126/science.aat1603
DP  - 2018 Jul 20
TA  - Science
PG  - 251--255
VI  - 361
IP  - 6399
4099  - http://science.sciencemag.org/content/361/6399/251.short
4100  - http://science.sciencemag.org/content/361/6399/251.full
SO  - Science2018 Jul 20; 361
AB  - The fluorescence of electrochromic molecules changes with their charge state. Doppagne et al. studied the optical emission of single zinc-phthalocyanine molecules excited by electron injection from a scanning tunneling microscope tip. The molecules were adsorbed on salt layers grown on a gold surface, so that the cationic and neutral molecules could both be observed. The primary emission shifted to lower energy for the cation, and, in addition, vibrational side bands were observed.Science, this issue p. 251The interplay between the oxidation state and the optical properties of molecules is important for applications in displays, sensors, and molecular-based memories. The fundamental mechanisms occurring at the level of a single molecule have been difficult to probe. We used a scanning tunneling microscope (STM) to characterize and control the fluorescence of a single zinc-phthalocyanine radical cation adsorbed on a sodium chloride–covered gold (111) sample. The neutral and oxidized states of the molecule were identified on the basis of their fluorescence spectra, which revealed very different emission energies and vibronic fingerprints. The emission of the charged molecule was controlled by tuning the thickness of the insulator and the plasmons localized at the apex of the STM tip. In addition, subnanometric variations of the tip position were used to investigate the charging and electroluminescence mechanisms.