Fluorescent N-Doped Graphene Quantum Dots Embedded in Transparent Polymer Films for Photon-Downconversion Applications

Abstract

In this work, we demonstrate a simple, facile, and efficient onepot synthesis of polymer−quantum dot nanocomposite films where nitrogendoped graphene quantum dots (N-GQDs) were homogeneously dispersed in UV-curable, transparent polymer host matrix via the thiol−ene "click" reaction pathway. The highly fluorescent NOA−NGQD nanocomposite films exhibited strong hydrophobicity with water contact angle (>69°) owing to restructuring of the polymer chain networks. The various functional groups of the N-GQD surface, as carbonyl, amine, and hydroxyl groups, provided more interactive sites and low agglomeration to develop the strong electrostatic interactions between the NOA and N-GQDs, resulting in flexible NOA−NGQDs nanocomposites. Thus, obtained NOA−NGQD nanocomposites exhibited high transparency (>90%), low band-gap, and strong fluorescence spectral peak (>500 nm) after the homogeneous inclusion of N-GQDs in the NOA polymer matrix. This study paves the way to diverse applications of functionalized GQDs as well as transparent polymers for the development of hydrophobic polymer−QD nanocomposites by using UV catalyzed thiol−ene chemistry. Hence, as synthesized nanocomposite films would be widely applicable in flexible electronic display devices, light emitting diodes (LEDs), and optoelectronic applications.

N, B-Codoping Induces High-Efficiency Solid-State Fluorescence and Dual Emission of Yellow/Orange Carbon Dots

“…o-NB-CDs, y-NB-CDs, and N-CDs show two obvious peaks at 1343, 1352, and 1370 cm –1 and 1621, 1621, and 1625 cm –1 , corresponding to the D band and G band, respectively. In general, the G band represents the vibration of well-organized graphitic carbon, and the D band represents the vibration of disordered or defective carbons, including the intrinsic carbon defect and heteroatom substitution defect, induced by oxygenated functional groups and doped B and N in CDs. , The value of I G / I D is the ratio of sp 2 /sp 3 carbons, which is used to evaluate the degree of graphitization of the CDs, and larger I G / I D indicates a higher degree of graphitization of the CDs . The Raman spectra were deconvoluted by Lorentzian fitting to obtain I G / I D .…”

Tunable Quantum Photoinitiators for Radical Photopolymerization

“…Nazim et al investigated the role of photopolymerization to generate a hydrophobic nanocomposite-based polymeric thin film hybrid [ 69 ]. The polymer–quantum dot nanocomposite films were synthesized via a simple one-pot, two-step procedure, in which nitrogen-doped graphene quantum dots (N-GQDs) were dispersed in a homogeneous manner within a UV-curable polymer host matrix via a thiol–ene “click” reaction ( Figure 10 ).…”

“…The NOA–NGQD nanocomposite films showed hydrophobic behavior, with water contact angle values greater than 69. Several heteroatom functionalities were introduced on the N-GQD surface (e.g., amine, carbonyl, and hydroxyl groups), which served as sites for electrostatic interactions between N-GQDs and NOA that led to the formation of flexible NOA–NGQDs nanocomposites [ 69 ]. The NOA–NGQD nanocomposites demonstrated high transparency (>90%) and a low band gap [ 72 ].…”

“…Nazim et al investigated the role of a photopolymerized polymeric thin film in constructing a copper indium gallium selenide solar cell with high efficiency [67]. The group utilized nitrogen-doped graphene quantum dots with transparency, highly emission, and UV-curable properties to fabricate highly dispersed Norland Optical Adhesive (NOA) nanocomposite-based polymeric thin films referred to as poly-QD films [67][68][69][70][71][72][73][74][75][76][77][78][79]. These flexible films served as luminescent downconversion (LDC) layers, which enhanced the function of copper indium gallium selenide solar cells.…”

“…Schmitt et al investigated the role of nanoscale ZnO with non-photo-reactive levulinic acid for initiating the polymerization of an acrylic ester mixture; the total amount of levulinic acid and the acidity of the reaction solution were shown to affect the photopolymerization process [6]. Nazim et al investigated the role of photopolymerization to generate a hydrophobic nanocomposite-based polymeric thin film hybrid [69]. The polymer-quantum dot nanocomposite films were synthesized via a simple one-pot, two-step procedure, in which nitrogen-doped graphene quantum dots (N-GQDs) were dispersed in a homogeneous manner within a UV-curable polymer host matrix via a thiol-ene "click" reaction (Figure 10).…”