White‐Light‐Emitting Melamine‐Formaldehyde Microspheres through Polymer‐Mediated Aggregation and Encapsulation of Graphene Quantum Dots. Issue 2 (22nd November 2018)

• Record Type: Journal Article
• Authors: Wu, Youshen; Zhang, Hui; Pan, Aizhao; Wang, Qi; Zhang, Yanfeng; Zhou, Guijiang; He, Ling
• Is Part Of: Advanced science. Volume 6:Issue 2(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-11-22
• Subjects: graphene quantum dots -- melamine‐formaldehyde -- microspheres -- white light emitting; Science -- Periodicals; 505
• DOI: 10.1002/advs.201801432
• Languages: English
• ISSNs: 2198-3844

Abstract

Abstract: Graphene quantum dot (GQD) encapsulated melamine‐formaldehyde (MF) polymer microspheres with uniform particle size and tunable high‐quality white‐light emissions are prepared via a polymer‐mediated GQD assembly and encapsulation strategy. In solution, GQDs are first aggregated with MF prepolymer through electrostatic interaction and further encapsulated inside the microspheres formed by polymerization of MF prepolymer under acid catalysis and heating. During this process, the aggregated GQDs are fixed in the MF polymer matrix with their emission extended from blue to full visible range, presenting bright white luminescence under ultraviolet excitation. The prepared white‐light‐emitting GQD‐MF microspheres exhibit uniform morphology with an average particle size of 2.0 ± 0.08 µm and their luminescence properties are effectively regulated by the doping concentration of GQDs in the MF polymer matrix. A series of white‐light‐emitting GQD‐MF microspheres with quantum yields from 0.83 to 0.43, Commission Internationale de L'Eclairage coordinates from (0.28, 0.28) to (0.33, 0.32), and color rendering index from 0.75 to 0.88 are obtained with excellent photostability and thermal stability. By dispersing the GQD‐MF microspheres in cross‐linked polydimethylsiloxane matrix, flexible film with dual functions of high‐quality white‐light‐emitting and light diffusion is obtained and successfully applied for white light‐emitting diode fabrication. Abstract : Graphene quantum dot (GQDs) encapsulated melamine‐formaldehyde (MF) polymer microspheres with a uniform particle size distribution and tunable high‐quality white‐light‐emission were prepared via polymer‐mediated assembly and encapsulation. The luminescent properties were effectively regulated by the doping concentrations of GQDs in the MF polymer matrix. The white‐light‐emitting GQDs‐MF microspheres showed excellent photo‐and thermal stability and were successfully used to fabricated white light‐emitting diodes.