Polymer-Assisted Self-Assembly of Multicolor Carbon Dots as Solid-State Phosphors for Fabrication of Warm, High-Quality, and Temperature-Responsive White-Light-Emitting Devices

Abstract

White-light-emitting devices (WLEDs) are considered to be a promising illumination source; especially, the WLEDs based on carbon dots (CDs) with white fluorescence have attracted extensive research interest. Herein, we report the design and implementation of solid white-light-emitting phosphors (WCDs@PS), which combine blue and orange emissive CDs (BCDs and OCDs) assisted by polystyrene (PS) through a self-assembly technique. Based on these phosphors (OCDs/BCDs = 1.2:1), the obtained WLEDs display a warm white light with International Commission on Illumination (CIE) coordinates of (0.35, 0.36), a high color rendering index of 93.2, a low correlated color temperature of 4075 K, and a luminous efficiency of up to 14.8 lm•W −1 . Interestingly, these WLEDs exhibit temperature-dependent emission performance, whose light-emission spectrum can be adjusted in situ from white (λ ∼ 400−730 nm) to blue (λ ∼ 440 nm) in the range of 20−80 °C. A change in CIE coordinates from (0.35, 0.36) to (0.32, 0.23) was also observed. The temperature-driven tunable LEDs as a thermochromism device could broaden the application of CDs-based lighting systems in special displays.

Evaluation of the Environmental Impact and Efficiency of N-Doping Strategies in the Synthesis of Carbon Dots

“…Furthermore, CDs can be produced through green and simple methods of synthesis [7], using even waste biomass as a precursor [8,9]. Given this, it is not surprising that CDs have attracted significant attention from the research community, and that they have been gaining several practical applications, such as in sensing [10][11][12], bioimaging [13], fabrication of light emission devices [14,15], and in photocatalysis [2].…”

“…Given this, it is not easy to predict the efficiency exerted by using different nitrogen precursors on the QY FL of the resulting CDs. This makes difficult the rational development of CDs with high QY FL , which is a feature required for most (if not all) current applications of these NPs [1][2][3][10][11][12][13][14][15]. In fact, it has not been fully assessed whether using either a nitrogen-rich solvent in a solvothermal route or a nitrogen-rich small organic molecule in a hydrothermal route would offer a greater potential.…”

The Rapid and Large‐Scale Production of Carbon Quantum Dots and their Integration with Polymers

“…can be simply prepared from CD/polymer solutions using different fabrication methods,s uch as molding, [51,52] dipcoating, [53] spin-coating, [54] drop-casting, [55,56] electrospinning, [58] drying, [59,60] and pH adjustment. [61][62][63][64] To date,various polymers have been applied, such as poly(methyl methacrylate) (PMMA), [51,52] polyvinyl alcohol (PVA), [54][55][56][57][58] polyvinyl pyrrolidone (PVP), [59] polycaprolactone (PCL), [33] chitosan (CS), [62] and starch. [61] In this case,C Ds with abundant functional groups are effectively conjugated with polymers through physical interactions,which results in good dispersion of the CDs in the polymers and avoidance of aggregationintroduced PL quenching.N otably,t he PL band positions of CD/polymer composites are not only dependent on the types and concentration of the CDs,b ut also on the polymer species.…”

Rare Earth‐Free Luminescent Materials for WLEDs: Recent Progress and Perspectives

“…The CIE coordinates of the prepared WLED were (0.35, 0.36), the CRI was 93.2, and the LE was as high as 14.8 lm W −1 . [51] Moreover, Shan et al obtained carbon-ZnO alternating QD chains through the selfassembly of negatively charged blue CDots and positively charged yellow emitting ZnO nanoparticles. The staggered chain structure formed by zinc oxide and CDots effectively overcame the aggregation quenching of the CDots, and consequently, the material presented a high PLQY of 49%.…”