Optical gap and fundamental gap of oligoynes and carbyne

Johannes Zirzlmeier (1) , Stephen Schrettl (2) , Jan Brauer (2) , Emmanuel Contal (2, 3) , Laurent Vannay (2) , Eric Brémond (2) , Eike Jahnke (1) , Dirk Guldi (1) , Clémence Corminboeuf (2) , Rik Tykwinski (4) , Holger Frauenrath (2)

1 ICMM - Inorganic Chemistry, Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM)
2 EPFL - Ecole Polytechnique Fédérale de Lausanne
3 UTINAM - Univers, Transport, Interfaces, Nanostructures, Atmosphère et environnement, Molécules (UMR 6213)
4 University of Alberta

The optoelectronic properties of various carbon allotropes and nanomaterials have been well established, while the purely sp-hybridized carbyne remains synthetically inaccessible. Its properties have therefore frequently been extrapolated from those of defined oligomers. Most analyses have, however, focused on the main optical transitions in UV-Vis spectroscopy, neglecting the frequently observed weaker optical bands at significantly lower energies. Here, we report a systematic photophysical analysis as well as computations on two homologous series of oligoynes that allow us to elucidate the nature of these weaker transitions and the intrinsic photophysical properties of oligoynes. Based on these results, we reassess the estimates for both the optical and fundamental gap of carbyne to below 1.6 eV, significantly lower than previously suggested by experimental studies of oligoynes.

Mots clés: Computational chemistry; Optical spectroscopy

Domaines: Chimie

Johannes Zirzlmeier, Stephen Schrettl, Jan Brauer, Emmanuel Contal, Laurent Vannay, et al.. Optical gap and fundamental gap of oligoynes and carbyne. Nature Communications, 2020, 11 (1), ⟨10.1038/s41467-020-18496-4⟩. ⟨hal-02962764⟩