The continuous white-light emission of carbon dots (CDs) can be applied to producing multicolor laser emissions by one single medium. Meanwhile, the solid-state emission greatly contributes to its practical application. In this work, a strategy to realize the in-situ hybridization of silane-functionalized CDs (SiCDs) and 1,3,5-benzenetricarboxylic acid trimethyl ester (Et3BTC) by a one-pot solvothermal method is reported. Significantly, the SiCDs/Et3BTC hybrid crystals exhibit ultra-broadband random laser emission over the near ultraviolet-visible region under 265 nm nanosecond pulsed laser excitation. The wavelength region of laser emission is achieved from 315 to 600 nm within an emission band of CDs-based materials. It is worth noting that the wavelength range of the laser is wider than the previously reported works. It is proposed that the continuous white-light emission of SiCDs caused by multiple fluorescence centers mainly gives rise to the broadband random laser emission. Moreover, the crystals are conducive to forming resonance and realizing solid-state laser emission. This in-situ method is expected to enable a more convenient, cheaper, and greener approach to prepare luminescent hybrids for application in multicolor laser displays, multi-level laser anti-counterfeiting, supercontinuum light sources, and so on.
Tanglue Feng,Qingsen Zeng,Siyu Lu,Xianju Yan,Junjun Liu,Songyuan Tao,Mingxi Yang,Bai Yang
In this paper, a unique strategy is proposed to modulate fluorescence color of carbon dots (CDs) under both aqueous solution and solid state for bright multicolor light-emitting diodes (LEDs) applications. We report facile synthesis of dual-peak-emissive CDs with self-quenching-resistant character under solid state through hydrothermal method, and investigate the origins of dual-peak emission for the first time. In addition, based on the unique dual-peak-emissive phenomenon, acid-mediated PL behaviors were realized by changing the pH value of hydrothermal precursors. We realized the color-tunable fluorescence under aqueous solution from blue (B-CDs) to yellow-green (YG-CDs) color and solid state from yellow to orange-red color. The changed PL behaviors are attributed to the more conjugated structure inside CDs due to elevated carbonization degree. Furthermore, the red-shifted fluorescence from aqueous solution to solid state is ascribed to supramolecular cross-linking between adjacent particles. Thus, by manipulating the supramolecular cross-linking degree of YG-CDs in PVA, a series of luminescent blue-shifted CDs/PVA composite phosphors were obtained. Finally, we fabricate the almost full-color and white color LEDs with decent performances, which indicate their potential for solid-state lighting applications.
Jiangchen Wu,Qiang Li,Xinghua Liu,Jingxia Zheng,Lin Chen,Yongzhen Yang,Chunhui Su
A simple and rapid one-step microwave-assisted method was employed to synthesize solid-state red emissive carbon dots (R-CDs) using phloroglucinol, urea, and ammonium fluoride in a high-boiling point solvent. Raw material ratios and solvent types were investigated. The optimal emission of R-CDs at 625 nm was achieved when the molar ratio was 3:1:6 in a 50% N , N -dimethyl formamide/water for 15 min. When formamide and water (v/v = 5:95) were used, R-CDs with longer emission (640 nm) were obtained and the reaction time was shortened to 3 min, enhancing both efficiency and cost-effectiveness. Both R-CDs maintained >96% fluorescence intensity after UV exposure and <5% weight loss at 200°C. Combined with polyvinyl pyrrolidone, R-CDs baesed red LEDs with CIE coordinates (0.67, 0.33) and (0.62, 0.38) were achieved. Combined with blue/green CDs, white LEDs showed color rendering indexes of 91–92. This study advances solid-state red CDs for high-quality white LEDs.
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