title: Exciton dynamics of C60-based single-photon emitters explored by Hanbury Brown-Twiss scanning tunnelling microscopy.
abstract: Exciton creation and annihilation by charges are crucial processes for technologies relying on charge-exciton-photon conversion. Improvement of organic light sources or dye-sensitized solar cells requires methods to address exciton dynamics at the molecular scale. Near-field techniques have been instrumental for this purpose; however, characterizing exciton recombination with molecular resolution remained a challenge. Here, we study exciton dynamics by using scanning tunnelling microscopy to inject current with sub-molecular precision and Hanbury Brown-Twiss interferometry to measure photon correlations in the far-field electroluminescence. Controlled injection allows us to generate excitons in solid C60 and let them interact with charges during their lifetime. We demonstrate electrically driven single-photon emission from localized structural defects and determine exciton lifetimes in the picosecond range. Monitoring lifetime shortening and luminescence saturation for increasing carrier injection rates provides access to charge-exciton annihilation dynamics. Our approach introduces a unique way to study single quasi-particle dynamics on the ultimate molecular scale.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Merino
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Große
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Rosławska
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Kuhnke
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstraße 1, Stuttgart 70569, Germany.|Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Kern