Electroluminescence from Graphene Quantum Dots Prepared by Amidative Cutting of Tattered Graphite

Abstract

Size-controlled graphene quantum dots (GQDs) are prepared via amidative cutting of tattered graphite. The power of this method is that the size of the GQDs could be varied from 2 to over 10 nm by simply regulating the amine concentration. The energy gaps in such GQDs are narrowed down with increasing their size, showing colorful photoluminescence from blue to brown. We also reveal the roles of defect sites in photoluminescence, developing long-wavelength emission and reducing exciton lifetime. To assess the viability of the present method, organic light-emitting diodes employing our GQDs as a dopant are first demonstrated with the thorough studies in their energy levels. This is to our best knowledge the first meaningful report on the electroluminescence of GQDs, successfully rendering white light with the external quantum efficiency of ca. 0.1%.

Multilevel Data Encryption Using Thermal‐Treatment Controlled Room Temperature Phosphorescence of Carbon Dot/Polyvinylalcohol Composites

“…The high resolution TEM (HRTEM) images of CD‐1 and CD‐2 reveal their lattice fringes to be 0.21 and 0.25 nm, which is consistent with the (102) and (100) lattice planes of graphitic carbon,33, 34, 35 respectively. As shown in Figure 1d, the X‐ray photoelectron spectroscopy (XPS) spectra of the CD‐1 and CD‐2 contain three peaks at 284.0, 400.0, and 530.6 eV, which are attributed to C 1s , N 1s , and O 1s , respectively 36, 37. The oxygen content decreases in CD‐2.…”

Recent Advances in Graphene Quantum Dots as Bioimaging Probes

“…Generally, the approaches can be divided into two groups: top-down and bottom-up methods. In the top-down methods, GQDs are usually synthesized through the cleavage of relatively large bulk precursors, such as graphite [53][54][55], carbon black [56][57][58], coal [59][60][61], metal-organic framework (MOF) [40], 3D graphene [62], graphene oxide (GO) [63][64][65][66][67], carbon nanotubes [68][69][70], carbon fiber [53,[71][72][73] and C 60 [74,75] into small pieces of graphene sheets by chemical oxidation etching [76][77][78][79][80][81], electrochemical exfoliation [65,[82][83][84][85], Li/K intercalation [86,87], hydrothermal/solvothermal treatment [88][89][90][91][92][93][94], microwave irradiation [95...…”

Properties and Synthesis Strategies of Graphene Quantum Dots

“…The top-down strategy involves cutting carbonaceous materials containing graphene sheets into smaller nanosheets through chemical and physical approaches, including hydrothermal, 16 solvothermal, 37 ultrasonic, 17 microwave 13 and electrochemical treatment, electron-beam lithography, pulsed laser. 38 The carbonaceous materials may be carbon fibers, 7 graphene, 30 GO, 39 graphite, 37,[40][41][42][43]44 carbon black, 45 carbon nanotubes, 46,47 coal.…”

“…38 The carbonaceous materials may be carbon fibers, 7 graphene, 30 GO, 39 graphite, 37,[40][41][42][43]44 carbon black, 45 carbon nanotubes, 46,47 coal. 48 Here, we summarize the top-down synthesis of GQDs and the related cutting mechanisms.…”