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Exploration of polymer-assisted crystallization kinetics in CsPbBr3 all-inorganic solar cell
摘要： All-inorganic perovskite material (CsPbBr3) has attracted enormous attention in photovoltaic devices due to superior stability. However, the thickness of CsPbBr3 film beyond 100 nm suffers from poor morphology, impurity phase and defects due to unbalance between fast growth and slow nucleation of film. Here, we introduce polyethylene glycol (PEG) into solution to achieve compact CsPbBr3 film with pure phase via a simple one-step solution process. The Lewis base of PEG interacts with the Lewis acid of Pb2+ to reduce the cluster size of CsBr-PbBr2-DMSO colloids as well as to increase the nucleation rate. The CsPbBr3 film magnitude less in intrinsic defect concentration is obtained by the addition of PEG. The open-circuit voltage increases from 1.15 eV to 1.41 eV with the highest efficiency of 7.8% as a result of less charge recombination of device, which is the highest efficiency ever recorded in one step solution process. The current–voltage curves measured at five different positions of large size device based on PEG (100 mm2) were almost identical, indicating highly uniform of devices. Thanks to the high quality of PEG modified CsPbBr3 film, there is no efficiency reduction during 120 h UV illumination. It was further used as a UV filter in tandem device which effectively restricts the UV degradation of bottom organic-inorganic perovskite solar cell. The tandem solar cell still remains 93% of the initial PCE after 120 h UV aging test, which are the main routes for commercializing device.
关键词： UV stability,CsPbBr3,Crystallization kinetics,Polyethylene glycol (PEG)
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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Application of PEGylated graphene quantum dots in cell imaging
摘要： Polyethylene glycol (PEG) functionalized graphene quantum dots (GQDs-PEG) with average particle size of 2.1 nm were successfully prepared by hydrothermal method with PEG as surface passivation agent. The quantum yield (QY) of GQDs-PEG was 3.7%and its physiological stability was significantly better than that of GQDs. The cell viability assay results showed that GQDs-PEG display no obvious toxicity to cells. The results of cell fluorescence imaging showed that GQDs-PEG could enter the whole cell with high fluorescence recognition.
关键词： cell imaging,graphene quantum dots,Polyethylene glycol
更新于2025-09-11 14:15:04
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Effects of Surface Passivation on Photoluminescence Properties and Biomedical Imaging of Graphene Quantum Dots
摘要： Owing to fluorescence properties and small size, graphene quantum dots (GQDs) have been investigated for biomedical imaging. Although GQDs demonstrate some desirable properties, their poor stability and low biocompatibility have applications in various aspects. Therefore, in this study, we synthesized surface-passivated GQDs and studied their properties. GQDs were prepared using thermal exfoliation of graphite oxide, followed by nitric acid refluxing. Then GQDs were passivated with polyethylene glycol (PEG) using hydrothermal at 120 ℃ for 72 h. Both GQDs and GQDs-PEG were characterized by transmission electron microscopy, UV-Vis absorption and photoluminescence spectroscopy. Compared with GQDs, GQDs-PEG exhibit higher fluorescence intensity and fluorescent quantum yield. Also, GQDs-PEG demonstrates less cytotoxicity than GQDs in terms of cell survival rate in MTT assay. Our findings demonstrate that both fluorescence characteristics and biocompatibility of GQDs can be improved by PEG surface passivation, and GQDs-PEG is desirable for biomedical imaging.
关键词： surface passivation,biomedical imaging,graphene quantum dots,photoluminescence,polyethylene glycol
更新于2025-09-10 09:29:36
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Fluorescent Metal-Semiconductor Hybrid Structures by Ultrasound-Assisted In-Situ Growth of Gold Nanoparticles on Silica-Coated CdSe-Dot/CdS-Rod Nanocrystals
摘要： Gold nanocrystals (AuNCs) were grown on the surface of silica coated CdSe-dot/CdS-rod core/shell nanocrystals by reduction of Au3+ ions in polyethylene glycol under ultrasonic irradiation. The polyethylene glycol not only prevents the penetration of gold ions or precursor molecules into the silica shell, but it also acts as the reducing agent for Au3+ ions. The silica shell’s surface promotes the heterogeneous nucleation of gold nanocrystals, while the ultrasonic irradiation accelerates and enhances the gold nucleation on the silica surface, and ensures the formation of AuNCs with a relatively narrow size distribution. The plasmon-exciton interaction in these metal-semiconductor hybrid systems leads to decreased fluorescence lifetimes and strongly reduced fluorescence blinking of individual hybrid structures.
关键词： ultrasonic irradiation,Gold nanocrystals,CdSe-dot/CdS-rod nanocrystals,plasmon-exciton interaction,polyethylene glycol
更新于2025-09-09 09:28:46