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Organogels Based on PEDOT:PSS and Carbon‐dots for Efficient Hole Transport in Organic Photovoltaics
摘要： Organic photovoltaic devices (OPVs) have received great attention in the past decades for next-generation renewable energy sources due to the low production cost and ?exible structure. The structure of OPVs is commonly composed of anode, hole transport layer (HTL), photoactive layer, and cathode. In general, an electrically conducting polymer such as poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) is used as the HTL to improve interfacial properties between the anode and photoactive layer. The PEDOT:PSS consists of hydrophobic and conductive PEDOT-chains doped with hygroscopic insulator PSS, resulting in poor electrical properties. It has been known that treatment of PEDOT:PSS with polar organic solvent or acid and annealing caused the conformational change and thus improved the electrical conductivity. However, controlling the orientation and shape of the PEDOT in PEDOT:PSS is still a challenge for improving the electrical percolation pathway. Recently, the electrical conductivity of PEDOT:PSS has been enhanced by inducing the gelation of PEDOT through self-assembly with graphene oxide (GO) and/or graphene quantum dots (GQDs). Although the gelation of PEDOT:PSS improved its mechanical, thermal, and electrical properties, its morphological changes and gelation mechanism in thin ?lms have not been well understood. In this letter is described the development of reticulated charge–transporting networks with enhanced electrical properties of self-assembled PEDOT:PSS organogels containing carbon-dots. Carbon-dots acted as a physical linker with PEDOT-chains in PEDOT:PSS through electrostatic interactions, resulting in the formation of a core–shell (carbon-dot@PEDOT) nanostructure. Furthermore, the blending ratio of carbon-dots and PEDOT:PSS and the gelation time affected the organogel ?lm morphology of a nanostructure which is associated with their electrical properties. The resulting carbon-dot@PEDOT:PSS organogel ?lms were applied as an HTL for typical poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) OPVs. As a result, the power conversion ef?ciency (PCE) of OPVs was enhanced by 30% due to the improvement of the electrical percolation pathway of the PEDOT:PSS ?lms.
关键词： PEDOT:PSS,Hole transport,Carbon-dots,Organic photovoltaics,Organogel
更新于2025-09-12 10:27:22
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Femtosecond Laser Synthesis of Luminescent Carbon Dots from Toluene
摘要： Products of reactions in toluene induced by nonlinear absorption of femtosecond laser pulses are studied. Laser synthesis of carbon dots with characteristic sizes of several nanometers and luminescence in the visible spectrum is demonstrated. A relation between synthesis conditions, morphology, and composition of carbon dots and their optical properties is established. The possibility of single-stage laser synthesis of polyethylene glycol passivated carbon dots having an enhanced quantum yield and improved spectral characteristics of luminescence is demonstrated. The results of the work open up new opportunities for obtaining promising carbon nanomaterials and optimizing their optical properties through the use of femtosecond laser pulses.
关键词： carbon dots,luminescence,toluene,femtosecond laser,polyethylene glycol
更新于2025-09-12 10:27:22
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One-step hydrothermal synthesis of down/up-conversion luminescence F-doped carbon quantum dots for label-free detection of Fe3+
摘要： In this work, a kind of down/up-conversion luminescent F-doped carbon dots (F-CDs) with high fluorescence quantum yield was prepared by one-step hydrothermal treatment of perfluorooctanoic sulfonate (PFOS) and was used for the label-free detection of Fe3+. The obtained F-CDs have a uniform and monodispersed size at 4 nm, and show good properties such as down/up-conversion luminescence, good water-solubility, anti-photo-bleaching, salt tolerance, and high fluorescence quantum yield of about 35.2%. The down/up-conversion photoluminescence emissions both are independent on the excitation and both the emission peaks are at 447 nm, which indicates it is promising to be used as fluorescent whitening agent. Based on the quenching effect of iron ions, a simple, sensitive, low-cost and label-free fluorescent assay for iron ions has been developed with a liner range of 1–100 μM and a limit of detection (LOD) of 10 nM. Furthermore, the label-free nanoprobe has been successfully applied for the detection of Fe3+ in real samples.
关键词： Fe3+,Down/up-conversion,Carbon dots,F-doped,Label-free detection
更新于2025-09-12 10:27:22
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Carbon Dots exhibiting Concentration-Dependent Full-Visible-Spectrum Emission for Light-Emitting Diode Applications
摘要： Carbon dots (CDs) that exhibit emission over the whole visible spectrum are desired for using in light-emitting diodes. Here, CDs displaying tunable fluorescence over the whole visible region are synthesized. Different concentrations of CDs are uniformly dispersed in epoxy resin and coated on 405-nm LED chips to obtain monochrome blue, cyan, green, yellow, red, and deep red LEDs that yield a color gamut covering 99.4% of the National Television Standards Committee (NTSC) standard. These monochrome LEDs display similar stability decay curves. Furthermore, warm and neutral white LEDs are produced by coating cyan- and red-emitting CD layers on 405-nm LED chips, achieving color rendering indexes (CRI) of 96.4 and 96.6, respectively. Two fluorescent conversion layers derived from one material at different concentrations simplifies the preparation of high-CRI white LEDs. The uniform weak changes of the cyan and red PL peaks during operation ensures the high stability of these CD-based white LEDs. This research provides a new avenue to develop low-cost, easy-to-prepare CDs with tunable emission colors as alternative phosphors for LED-based high-performance displays and lighting.
关键词： full-visible-spectrum emission,monochrome light-emitting diodes,concentration-dependent spectrum-tunable carbon dots,high color rendering index,white-light-emitting diodes
更新于2025-09-12 10:27:22
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[IEEE 2019 3rd International Conference on Circuits, System and Simulation (ICCSS) - Nanjing, China (2019.6.13-2019.6.15)] 2019 3rd International Conference on Circuits, System and Simulation (ICCSS) - Carbon Dots/Graphene Hybrids for UV Photodetectors
摘要： The intrinsical poor optical absorption and short carrier lifetime of graphene have restricted its practical application of photodetectors. Carbon dots (CDs) have received much attention due to their fascinating optical properties, environmentally-friendly nature, small size and superiority of a large optical absorptivity. Thus, in this work, hybrid photodetector of graphene and CDs has been proposed for the deep-UV photodetection, in which CDs integrated with graphene to form a planar hybrid structure. An inverse photo-electricity response was observed after illumination, which means the decline of conductivity under irradiation. The mechanism for this behavior is attributed to the built-in electric field generated across the interface between graphene layer and CDs layer, which separates the photogenerated electrons and holes, and promotes the holes to graphene layer and electrons to CDs layer. Our result demonstrates that the integration of graphene and CDs shows better optical absorption and wavelength selectivity. Together with the mechanism, it paves a step for practical applications of quantum dots sensitized graphene-based photodetectors.
关键词： heterostructure,carbon dots,photodetector,graphene
更新于2025-09-12 10:27:22
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Surface state-controlled C-dot/C-dot based dual-emission fluorescent nanothermometers for intra-cellular thermometry
摘要： Fluorescence-based nanothermometers have potential to offer accuracy in the measurement of temperature using non-contact approaches. Herein, a C-dot/C-dot based dual-emission temperature sensing platform is fabricated through the electrostatic self-assembly of two kinds of fluorescent CDs with opposite charges. This dual-emission platform consists of several nearly-spherical CDs with two emission centers in blue (440 nm) and orange (590 nm) regions. The orange fluorescence exhibits discernible response to external temperatures in the range of ～15 to 85 °C; on the other hand, the blue fluorescence remains nearly constant. A continuous fluorescence color change in response to temperature from orange to blue can be clearly observed by the naked eye. Thus, the as-prepared C-dot based dual-emission nanospheres can be used for optical thermometry with high reproducibility and sensitivity (0.93%/°C). Detailed characterization shows that temperature (in the 15–85 °C window) impacts the surface states of orange emissive CDs, leaving the blue emissive CDs unaffected. A model is proposed to explain the observations. Finally, by taking advantage of the excellent biocompatibility and stability, the CD based fluorescent nanothermometer is successfully used for the visual measurement of intracellular temperature variations.
关键词： intracellular thermometry,temperature sensing,nanothermometers,dual-emission,fluorescence,carbon dots
更新于2025-09-11 14:15:04
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Sonochemical Synthesis of Carbon Dots/Lanthanoid MOFs Hybrids for White Light-Emitting Diodes with High Color Rendering
摘要： Although lanthanoid metal-organic frameworks (Ln-MOFs) have been widely developed for white light-emitting diodes (WLEDs), the color rendering index (CRI) values are still lower than 80. To overcome this limitation, a series of carbon dots/Ln-MOFs hybrids namely CDs-2@Ln-MOF, CDs-3@Ln-MOF and CDs-4@Ln-MOF containing blue emitting CDs and yellow emitting bimetallic [(Eu1.22Tb0.78(1,4-phda)3(H2O)](H2O)2 were prepared via sonication at room temperature to restrict the self-quenching of CDs in composite materials. The as-synthesized composite materials were investigated by FT-IR, PXRD, TEM, SEM and photoluminescence. The luminescent color of the materials can be adjusted by varying the amount of CDs and excitation wavelengths. The resulting CDs-3@Ln-MOF achieved excellent CRI up to 93 with the ideal CIE coordinate (0.334, 0.334) and appropriate correlated color temperature, CCT (5443 K). In addition, the tunable multi-colored luminescence based on single and bimetallic EuxTb2-x(1,4-phda)3(H2O)](H2O)2; x = 0, 0.73, 1.22, 1.57, 1.94 and 2 were applied as the luminescent security inks for anti-counterfeiting application through encoding/decoding and rewritable data.
关键词： anti-counterfeiting,luminescence material,white light-emitting diodes,metal-organic frameworks,carbon dots
更新于2025-09-11 14:15:04
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Carbon Dots as Cosensitizers in Dye-Sensitized Solar Cells and Fluorescence Chemosensors for 2,4,6-Trinitrophenol Detection
摘要： Carbon dots (CDs) are a unique class of fluorescent nanomaterials, whose emissions can be tuned by manipulating the reaction conditions of their formation. Herein, we report a facile solvothermal route for producing CDs with tunable properties by employing N,N-dimethylformamide (DMF) as the solvent medium. Using completely green carbon sources, two types of CDs are synthesized: citric acid produces green emitting CDs (G-CDs) while gallic acid produces blue emitting CDs (B-CDs). The optical analysis of the G-CDs suggests their application as co-sensitizers along with N719 dye in dye sensitized solar cells (DSSCs). Following this, the effect of G-CDs in DSSCs was studied and a photo-conversion efficiency of 6.9% was extracted from the device. Meanwhile, the B-CDs produced from gallic acid are hydrophobic in nature and their blue colored emission is quenched in the vicinity of TNP in less than 1 min with a limit of detection of 0.75 μM.
关键词： Carbon dots,Fluorescence chemosensor,Dye sensitized solar cells,2,4,6-Trinitrophenol detection
更新于2025-09-11 14:15:04
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Optimization and performance of nitrogen-doped carbon dots as a color conversion layer for white-LED applications
摘要： In this study, green-emitting nitrogen-doped carbon dots (N-CDots) were synthesized and incorporated into drop-cast composite films for use as color conversion layers in a white-LED configuration to generate white light. In order to resolve the red deficiency of this configuration, a commercial red phosphor was integrated into the system. Moreover, the N-CDots were also processed into polymer/N-CDot composite fibers, for which we determined the amount of N-CDots that yielded adequate white-light properties. Finally, we showed that white light with excellent properties could be generated by employing both of the fabricated N-CDot composites either as drop-cast films or composite fibers. Hence, N-CDots provide a promising alternative to inorganic phosphors that are commonly employed in white-LED configurations.
关键词： PVP,nitrogen-doped carbon dots,color conversion layer,electrospinning,white-light generation,white LED,solid-state lighting
更新于2025-09-11 14:15:04
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Mechanistic Insight into the Carbon Dots: Protonation induced Photoluminescence
摘要： Although several theories have been proposed, the mechanism of complex photoluminescence in carbon dots (CNDs) is a central quest till date. This report presents pH dependent steady state and time resolved spectroscopy study which identifies a possible origin of the complex photoluminescence in CNDs. The multiple emissive species created by the excited state protonation-deprotonation reaction at certain pH gives rise to inhomogeneous broadening and consequently excitation dependent multicolour emission. The origin of the excited state dynamics is attributed to the significant change of the proton dissociation between ground and excited state. We present a new model on protonation dynamics and show how it affects the emissive states in CNDs.
关键词： time resolved fluorescence,origin of photoluminescence,pH dependence,Carbon dots,Excited state protonation
更新于2025-09-10 09:29:36