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The intrinsically disordered periodic architecture inherent in natural biomaterials exhibits significant potential for serving as resonant cavities, enabling the development of eco-friendly, biocompatible, and cost-effective microlaser systems. In this study, we demonstrate a biomaterial-based random laser utilizing birch leaf-derived carbon dots (CDs) as the gain medium. CDs ethanol solution was introduced into the peanut via microinjection, successfully fabricating CDs-doped peanut samples that preserved the fluorescence characteristics of the CDs in solution. Random lasing was observed on multiple surfaces of the CDs-doped peanut under pulsed laser excitation, with varying thresholds across different regions. This demonstrates that the natural disordered microstructure of biological materials can facilitate random lasing. Analysis of surface morphology and scattering patterns indicates that the lasing mechanism arises from multiple light scattering within the disordered structure of the peanut surface, forming coherent feedback loops. Furthermore, the intrinsic biocompatibility of bio-derived CDs effectively addresses the persistent toxicity concerns associated with synthetic laser materials. Such biomaterial-based random lasers could enable eco-friendly and cost-effective photonic applications.

The synthesis of carbon dots (CDs) with tailored properties commonly requires time-consuming trial-and-error experimentation, in part because of a poorly understood and controlled chemical conversion of the precursor material. Here, we first report on the solid-state pyrolysis or solvothermal conversion of an ortho-aminophenol (oAP) precursor, comprising ortho-disposed amino and hydroxyl groups on a benzene ring. We find that both conversion reactions resulted in a two emission-colour product, which could be separated into distinct blue-emitting CDs (bCDs, λpeak = 420 nm) and yellow-emitting CDs (yCDs, λpeak = 565 nm) by repetitive column chromatography. Systematic characterization revealed that both CDs comprise a planar graphene-like interior, but that they are distinguished by that the bCDs comprise an intermixed significant amino-rich fluorophore while the yCDs instead comprise a pyridinic-rich fluorophore. This implies that the bCDs are formed via activation of the amino group of the oAP precursor, whereas the synthesis of the yCDs constituted a simultaneous activation of both the amino and hydroxyl groups. With this knowledge at hand, we managed to direct the chemical conversion of the oAP precursor to yield either solely bCDs or yCDs by adding a catalyst (either the Lewis acid AlCl3·6H2O or the Lewis base NaOH) that selectively and efficiently activated only one of the reaction pathways. This demonstration is important in that it shows that the synthesis of CDs with desired properties can be realized with efficient rational instead of trial-and-error means.

Deep-blue (DB) emitters that feature high photoluminescence quantum yield (PLQY) and narrow spectral bandwidth are desired for a variety of optoelectronic applications, particularly for lighting, illumination, and lasing. Currently favored DB emitters constitute quantum dots comprising cadmium or lead and organic compounds derived from petroleum, but they suffer from toxicity and sustainability issues. Here, we report the solvothermal synthesis of DB-emitting carbon dots (DB-CDs) using bioderivable phloroglucinol as the sole starting material, which exhibit a peak emission wavelength of 403 nm, narrow spectral full width at half-maximum of 35 nm, and high PLQY of 61% in ethanol. The DB-CDs with a planar structure are demonstrated to comprise distinct graphene segments in a polyether-cross-link network, with the former functioning as the fluorophore. The application merit of the DB-CDs is exemplified by their implementation as the gain medium in a random laser device, which exhibits a threshold optical power density of 40.5 kW cm-2. This study thus demonstrates a path toward efficient and sustainable deep-blue emitters, which can be exploited in practical applications.

Blue light emitted by commercial white light-emitting diodes (WLEDs) in the 440-470 nm range poses ocular health risks with prolonged exposure. Effective filtration is crucial for health-conscious lighting, but traditional filters often cause color distortion by completely removing blue emission. In this study, we address this challenge by synthesizing carbon dots (CDs) with strong absorption at 460 nm and bright cyan emission at 485 nm, featuring a photoluminescence quantum yield of 65% and a narrow full width at half-maximum of 30 nm. When embedded in a poly(vinyl alcohol) (PVA) matrix, the CDs@PVA films effectively filter UV-to-blue light, reducing the blue-light ratio from 27.2% to 2.7%. At the same time, the cyan emission preserves the white light’s spectral composition, achieving a color rendering index of 83 ± 5. This dual functionality demonstrates the potential of CDs to enable safer WLEDs that improve both ocular health and lighting quality.

Emissive carbon dots (CDs) that are synthesized from biomass can be highly sustainable, but the number of reported biomass-derived CDs that emit in the ultraviolet (UV) range is small. Moreover, current commercial UV-emitting materials rely heavily on the use of non-sustainable resources, such as rare metals, heavy metals, and petroleum chemicals. This yields that the development of efficient biomass-derived UV-CDs is desired. Here, we report on the hydrothermal conversion of a common green-tea extract (Polyphenon 60) into UV-CDs, which feature a photoluminescence (PL) peak wavelength of 384 nm, a full width at half maximum of 72 nm, and a photoluminescence quantum yield (PLQY) of 17% in water. By shifting to a lower-polarity solvent of 3-phenoxyanisole, the PLQY is strongly enhanced to 81%, and the PL peak blue-shifts to 370 nm, while the maximum solubility is lowered. These observations support the notion that the UV-CDs feature aggregation-induced emission and that they are endowed with hydrophilic surface groups. Moreover, the findings of excitation-wavelength-independent PL and a nanosecond-level short emission lifetime reveal that it is a single distinct fluorophore that produces the UV emission. We finally report preliminary results that the UV-CDs exhibit potential for inhibiting the proliferation of cancer cells.

Near-ultraviolet (NUV) light is critical for applications in lighting, manufacturing, and medical fields, yet existing NUV emitters often suffer from complex syntheses or rely on toxic or unsustainable materials. Herein, we present a facile solvothermal synthesis of high-efficiency, narrow-band NUV-emitting carbon dots (NUV-CDs) derived from bio-derivable phloroglucinol. These NUV-CDs exhibit a sharp emission peak at 403 nm with a high photoluminescence quantum yield (PLQY) of 60 % and a narrow full width at half maximum (FWHM) of 35 nm in ethanol solution. Structural and spectroscopic analyses reveal that the NUV-CDs are formed through dehydration and dehydrogenation reactions, resulting in a single type of emissive center with weak environmental interactions. When integrated into a polyvinyl alcohol (PVA) matrix and applied as a light-conversion coating on a UV-LED chip, the resulting device emits at 408 nm with an FWHM of 50 nm and an exceptional color purity of 87.7 %. This study offers a promising, environmentally friendly alternative for high-performance NUV light sources, complementing the spectral gap of existing CD materials.

Halide perovskite quantum dots (PeQDs) have garnered significant attention for their exceptional optoelectronic properties, particularly in light-emitting diode (LED) applications. However, their susceptibility to thermal degradation at elevated temperatures (>100 °C) poses a critical barrier to commercialization. In this study, we address this challenge through a synergistic ZnF2 post-treatment strategy applied to CsPbBr3 PeQDs. Comprehensive experimental characterizations and density functional theory (DFT) calculations reveal that the ZnF2 treatment induces the formation of a dual-shell structure: CsPbBr3: F inner shell and a zinc-rich outer shell chemically that bonds with Br and F ions from the CsPbBr3: F layer. The inner shell primarily suppresses thermal degradation, while both shells collaboratively mitigate surface defects. This dual-shell engineering endows the CsPbBr3 PeQDs with remarkable thermal stability, maintaining their optical properties and crystallinity even after heating at 120 °C for 60 min, alongside achieving near-unity photoluminescent quantum yield. Furthermore, the dual-shell PeQDs exhibit a 24-fold enhancement in device lifespan in electroluminescent LEDs and superior operational stability in photoluminescent white LEDs. This work offers a simple yet highly effective approach to fabricating thermally stable PeQDs, paving the way for their practical application in next-generation optoelectronic devices.

Quercetin, a flavonoid known for its antioxidant properties, has recently garnered attention as a potential neuroprotective agent for treatment of the injured nervous system. The repair of peripheral nerve injuries hinges on the proliferation and migration of Schwann cells, which play a crucial role in supporting axonal growth and myelination. In this study we synthesized Quercetin-derived carbon dots (QCDs) and investigated their effects on cultured Schwann cells and the NG108-15 cell line. QCDs was obtained by solvothermal synthesis and characterized via UV–vis absorption spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The particles demonstrated significant dose-dependent free radical scavenging activity in DPPH and ABTS radical scavenging assays, supported in vitro proliferation and migration of Schwann cells, expression of neurotrophic and angiogenic growth factors, and stimulated neurite outgrowth from NG108-15 cells. Thus, QCDs could serve as a potential novel treatment strategy to promote regeneration in the injured peripheral nervous system.

The attainment of white emission from a light-emitting electrochemical cell (LEC) is important, since it enables illumination and facile color conversion from devices that can be cost-efficient and sustainable. However, a drawback with current white LECs is that they either employ non-sustainable metals as an emitter constituent or are intrinsically efficiency limited by that the emitter only converts singlet excitons to photons. Organic compounds that emit by thermally activated delayed fluorescence (TADF) can address these issues since they can harvest all excitons for light emission while being metal free. Here, we report on the first white LEC based on solely metal-free TADF emitters, as accomplished through careful tuning of the energy-transfer processes and the electrochemically formed doping structure in the single-layer active material. The designed TADF-LEC emits angle-invariant white light (color rendering index = 88) with an external quantum efficiency of 2.1 % at a luminance of 350 cd/m².

Cadmium-free AgInZnS (AIZS) quantum dots (QDs) have garnered significant research interest for applications in light-emitting diodes (LEDs); however, their performance remains limited by insulating long-chain ligands. In this study, highly fluorescent orange-emitting AIZS QDs are synthesized by replacing long-chain 1-dodecanethiol (DDT) with short-chain 1-octanethiol (OTT), achieving photoluminescence quantum yields of up to 80% in solution and 60% in film. The incorporation of OTT in combination with oleic acid and oleylamine as co-capping ligands enabled excellent dispersion of the QDs in non-polar solvents. The resulting OTT-capped AIZS QDs exhibited improved film smoothness and reduced nonradiative recombination. Furthermore, all-solution-processed QD light-emitting diodes (QLEDs) are fabricated comprising indium tin oxide/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate/hole transporting layer/AIZS QDs/ZnO electron transporting layer/Al. The effects of OTT capping and the thickness of the AIZS emitting layer on device performance are systematically evaluated. As a result, the QLEDs demonstrated enhanced luminance and current efficiency, reaching 515 cd m⁻² and 0.4 cd A⁻¹ respectively, representing improvements of over 50% and 33% compared to devices utilizing DDT-capped AIZS QDs. This study presents a facile and effective approach for developing high-brightness AIZS QLEDs.