title: pH-Dependent Synthesis of Novel Structure-Controllable Polymer-Carbon NanoDots with High Acidophilic Luminescence and Super Carbon Dots Assembly for White Light-Emitting Diodes.
abstract: We use a pH-dependent solubility equilibrium to develop a one-pot aqueous synthesis of polymer carbon nanodots with novel structures. The chemical structure and photoluminescence (PL) were heavily influenced by the synthesis pH, with cross-linked polymer-carbon film (pH > 7), polymer carbon nanosheets (3 < pH < 7), and amorphous carbon structures (1 < pH < 3) achieved by altering the initial pH. Although pH-dependent structures frequently occur in typical semiconductors and supramolecular architectures involving metal, this is the first experimental work describing it in carbon nanodots. Supersmall carbon nanodots (SCNDs, ∼0.5 nm) were obtained at pH < 1; their direct white emission can be easily applied as an inexpensive color-changing layer in white LEDs. Investigation of the PL mechanism of the SCNDs revealed an uncommon multilevel highly emissive recombination channel, which could be possibly derived from the wide distributions of surface-state PL centers. Theoretical calculation of the single layer of the carbon dots further explored their band gap changes.
authors.affiliation: Department of Physics and Engineering Physics, University of Saskatchewan , Saskatoon, Saskatchewan S7N 5E2, Canada.
authors.forename: Siyu
authors.initials: S
authors.lastname: Lu
authors.affiliation: Hebei Key Laboratory of Optic Electronic Information Materials, College of Physics Science and Technology, Hebei University , Baoding 071002, P. R. China.
authors.forename: Ridong
authors.initials: R
authors.lastname: Cong
authors.affiliation: Department of chemistry, Stanford University , Stanford, California 94305, United States.
authors.forename: Shoujun
authors.initials: S
authors.lastname: Zhu
authors.forename: Xiaohuan
authors.initials: X
authors.lastname: Zhao
authors.forename: Junjun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Physics and Engineering Physics, University of Saskatchewan , Saskatoon, Saskatchewan S7N 5E2, Canada.
authors.forename: John
authors.initials: J
authors.lastname: S Tse
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences , 100190 Beijing, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Meng
authors.forename: Bai
authors.initials: B
authors.lastname: Yang
keywords: carbon core state; carbon dots; fluorophore; molecular state; structure controllable