Multicolor Graphene Quantum Dots via Solvatochromic Tuning and Sulfur Doping for Light-Emitting Diodes

Abstract

Recently, graphene quantum dots (GQDs) with polychrome emission capability have attracted much attention due to their multifarious applications. In this study, we report a facile and green approach for rapid preparation of multicolor emission GQDs. Experimentally, UV light was used to drive the lowtemperature synthesis, and a tunable emission wavelength of the GQDs was achieved through the synergistic effect of solvatochromic tuning and sulfur doping. Results show that multicolor emission wavelengths of green-GQDs (G-GQDs) from blue to yellow are obtained by simply controlling the polarity of the surrounding solutions. Moreover, red-GQDs with the emission wavelengths extended from green to red are further obtained by sulfur doping. Thereafter, G-GQDs were used to develop a trace water-detecting platform, ascribed to the high sensitivity of water-quenchable fluorescence, and a low detection limit of 0.061% was achieved. Meanwhile, based on the outstanding multicolor tunability of as-prepared GQDs, we successfully manufactured multicolor solid fluorescence films to fabricate multicolor light-emitting diode (LED) devices. Furthermore, high-quality white LEDs (WLEDs) are fabricated with the CIE coordinates of (0.341, 0.354) and a color temperature of 5161 K. This study highlights the potential of GQDs in various applications, including solid-state fluorescence films, optoelectronics, and optical molecular sensing.

Engineering functionalization and properties of graphene quantum dots (GQDs) with controllable synthesis for energy and display applications

“…218 Recently, Xu et al utilized N-GQDs powder as a single emitter in LEDs to achieve WLEDs with CIE coordinates of (0.28, 0.31), a CCT of 7469 K, and a CRI of 92.3. 350 Yang et al have shown that by controlling solvent polarity and S-doping, the emission wavelength of GQDs can be adjusted from blue to red, and these multicolor GQDs can be used as the fluorescent layer in LEDs, resulting in a WLED with CIE coordinates of (0.341, 0.354) and a CCT of 5161 K. 351 On the other hand, the aggregation that occurs in the solidstate GQDs can lead to the PL quenching effect through ACQ, which can compromise the emitting performance of LEDs. Therefore, it is crucial to prevent aggregation when applying GQDs in LEDs.…”

Synthesis and post-synthesis strategies for polychromatic carbon dots toward unique and tunable multicolor photoluminescence and associated emission mechanism

“…Yang et al in another study conducted S-doping into the N-doped CDs to obtain polychromatic CDs (547–612) using UV light treatment at low temperature from o -phenylenediamine and catechol precursor. 76 S-doping specifically tunes the emission wavelength to longer wavelength region (red emission). According to them, the increase in the oxygen content on the surface and nitrogen content in the graphitic structure drives the emission to longer wavelength.…”

Identification of Chinese baijiu from the same brand based on a graphene quantum dots fluorescence sensing array

“…43,44 Hydrogen bonding also becomes more important in the interaction of GQDs with solvents due to the presence of protonating groups such as nitrogen-containing substances. 45 To verify that the constructed uorescence sensor array can effectively discriminate between different environments, the most dominant species, ethanol and water in white wine were used. Six different concentrations of ethanol-water mixture solutions were detected.…”