title: Deep ultraviolet photoluminescence of water-soluble self-passivated graphene quantum dots.
abstract: Glucose-derived water-soluble crystalline graphene quantum dots (GQDs) with an average diameter as small as 1.65 nm (∼5 layers) were prepared by a facile microwave-assisted hydrothermal method. The GQDs exhibits deep ultraviolet (DUV) emission of 4.1 eV, which is the shortest emission wavelength among all the solution-based QDs. The GQDs exhibit typical excitation wavelength-dependent properties as expected in carbon-based quantum dots. However, the emission wavelength is independent of the size of the GQDs. The unique optical properties of the GQDs are attributed to the self-passivated layer on the surface of the GQDs as revealed by electron energy loss spectroscopy. The photoluminescence quantum yields of the GQDs were determined to be 7-11%. The GQDs are capable of converting blue light into white light when the GQDs are coated onto a blue light emitting diode.
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong SAR.
authors.forename: Libin
authors.initials: L
authors.lastname: Tang
authors.forename: Rongbin
authors.initials: R
authors.lastname: Ji
authors.forename: Xiangke
authors.initials: X
authors.lastname: Cao
authors.forename: Jingyu
authors.initials: J
authors.lastname: Lin
authors.forename: Hongxing
authors.initials: H
authors.lastname: Jiang
authors.forename: Xueming
authors.initials: X
authors.lastname: Li
authors.forename: Kar Seng
authors.initials: KS
authors.lastname: Teng
authors.forename: Chi Man
authors.initials: CM
authors.lastname: Luk
authors.forename: Songjun
authors.initials: S
authors.lastname: Zeng
authors.forename: Jianhua
authors.initials: J
authors.lastname: Hao
authors.forename: Shu Ping
authors.initials: SP
authors.lastname: Lau
mesh_terms: D003116:Color; D006108:Graphite / Q000737:chemistry*; D049449:Luminescence; D008422:Materials Testing; D045663:Quantum Dots; D012995:Solubility; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D006108:Graphite