title: Biexciton Binding of Dirac fermions Confined in Colloidal Graphene Quantum Dots.
abstract: We present transient absorption measurements and microscopic theory of biexciton binding in triangular colloidal graphene quantum dots consisting of 168 sp(2)-hybridized C atoms. We observe optical transitions from the lowest orbitally dark singlet exciton states to states below the energy of an unbound dark+bright singlet-exciton pair. Through microscopic calculations of the low-energy exciton and biexciton states via tight-binding, Hartree-Fock, and configuration interaction methods, the spectra reveal a biexciton consisting primarily of a dark-bright singlet-pair bound by ∼0.14 eV.
authors.affiliation: †Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, United States.
authors.forename: Cheng
authors.initials: C
authors.lastname: Sun
authors.affiliation: †Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, United States.
authors.forename: Florian
authors.initials: F
authors.lastname: Figge
authors.affiliation: §Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Isil
authors.initials: I
authors.lastname: Ozfidan
authors.affiliation: ‡Quantum Theory Group, Security and Disruptive Technologies, Emerging Technologies Division, National Research Council of Canada, Ottawa, Ontario, K1A OR6 Canada.
authors.forename: Marek
authors.initials: M
authors.lastname: Korkusinski
authors.affiliation: ∥Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
authors.forename: Xin
authors.initials: X
authors.lastname: Yan
authors.affiliation: ∥Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States.
authors.forename: Liang-shi
authors.initials: LS
authors.lastname: Li
authors.affiliation: §Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
authors.forename: Pawel
authors.initials: P
authors.lastname: Hawrylak
authors.affiliation: †Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824, United States.
authors.forename: John A
authors.initials: JA
authors.lastname: McGuire
mesh_terms: D003102:Colloids / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry*
chemical_list: D003102:Colloids; D007477:Ions; D006108:Graphite
keywords: Dirac fermions; Graphene quantum dot; Hartree−Fock; biexciton binding; configuration interaction; transient absorption