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Ketone derivatives as photoinitiators for both radical and cationic photopolymerizations under visible LED and application in 3D printing
摘要： Six ketones (abbreviated as ketones 1-6) varying by the substitution pattern of the central cyclohexanones and the choice of the peripheral groups (thiophene or furane) were synthesized and proposed as unprecedented visible light sensitive photoinitiators, in combination with an amine and an iodonium salt, for the free radical polymerization of acrylates upon LED irradiation at 405 nm. For the photopolymerization of acrylates carried out as thin samples in laminate, all these ketones showed high photoinitiating abilities. Conversely, when tested as photoinitiators for thick samples, compared to the other 4 ketones, ketone 3 and ketone 5 both based onpiperidin-4-one as the central core and comprising furanes as peripheral groups proved to be the most efficient photoinitiators. Notably, the highest final polymerization conversion of Ebecryl 40, a tetrafunctional polyether acrylate, could be obtained using these two photoinitiators. The high photoreactivity of ketone 3 was highlighted by the steady state photolysis experiments. Meanwhile, ketone 3 could also promote the cationic polymerization of epoxides upon LED irradiation at 405 nm, in the presence of an iodonium salt. Interestingly, some 3D patterns could also be fabricated by free radical polymerization of Ebecryl 40 while using the ketone 3-based photoinitiating system.
关键词： free radical polymerization,ketones,cyclohexanone,photolysis,3D printing,cationic polymerization,LED,photoinitiating system
更新于2025-09-23 15:21:01
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Over 6% Efficient Cu(In,Ga)Se2 Solar Cell Screen-Printed from Oxides on FTO
摘要： A new approach to fabricate copper, indium, gallium diselenide (CIGSe) solar cells on conductive fluorine-doped tin oxide (FTO) reached an efficiency of over six per cent for champion photovoltaic device. Commercial oxide nanoparticles are formulated into high-quality screen printable ink based on ethyl cellulose solution in terpineol. The high homogeneity and good adhesion properties of the oxide ink play an important role in obtaining dense and highly crystalline photoabsorber layers. This finding reveals that solution-based screen printing from readily available oxide precursors provides an interesting cost-effective alternative to current vacuum- and energy-demanding processes of the CIGSe solar cell fabrication.
关键词： screen-printing,ink formulation,photovoltaics,CIGSe,microstructure,oxides nanoparticles
更新于2025-09-23 15:21:01
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Numerical studies of metal particle behaviors inside the selective laser melting (SLM) chamber through computational fluid dynamics (CFD)
摘要： The flow behavior of the shielding gas has been a key factor to improve the quality of products manufactured by the selective laser melting (SLM) technology as it is a major mechanism to remove the ejected metal particles away from the working plane. In this study, to obtain a proper flow field, computational fluid dynamics (CFD) with the application of the Taguchi method was employed to investigate the flow field across the working chamber, with the variations in the geometries of the blowing nozzle, the widths of the suction tunnel, the suction-to-plane distances, and the Reynolds numbers of the blowing flow. The simulation was first verified with experimental measurements. The ejecting motions of the metal powders were also taken into consideration to study the interactions between the shielding gas and the ejected particles. The results demonstrated that axis switching as well as the suction-to-plane distance are the important factors for improving the particle removal efficiency during the SLM operation.
关键词： Selective laser melting,Computational fluid dynamics,Particle removal efficiency,3-D printing,Axis switching,Taguchi method
更新于2025-09-23 15:21:01
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Selective Laser Sintering 3D Printing a?? An Overview of the Technology and Pharmaceutical Applications
摘要： Food and Drug Administration (FDA) has approved a drug product (Spritam?) and many medical devices manufactured by 3-dimensional printing (3DP) processes for human use. There is immense potential to print personalized medicines using 3DP. Many 3DP methods have been reported in the literature for pharmaceutical applications. However, selective laser sintering (SLS) printing has remained least explored for pharmaceutical applications. There are many advantages and challenges in adopting a SLS method for fabrication of personalized medicines. Solvent free nature, availability of FDA approved thermoplastic polymer/excipients (currently used in hot melt-extrusion process), minimal/no post-processing step, etc. are some of the advantages of the SLS printing process. Major challenges of the technology are requirement of at least one thermoplastic component in the formulation and thermal stability of drug and excipients. This review provides an overview of the SLS printing method, excipient requirements, process monitoring, quality defects, regulatory aspects and potential pharmaceutical applications.
关键词： in-process monitoring,selective laser sintering,personalized medication,3D printing,quality defects,pharmaceuticals
更新于2025-09-23 15:21:01
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High efficiency and stability of ink-jet printed quantum dot light emitting diodes
摘要： The low efficiency and fast degradation of devices from ink-jet printing process hinders the application of quantum dot light emitting diodes on next generation displays. Passivating the trap states caused by both anion and cation under-coordinated sites on the quantum dot surface with proper ligands for ink-jet printing processing reminds a problem. Here we show, by adapting the idea of dual ionic passivation of quantum dots, ink-jet printed quantum dot light emitting diodes with an external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours were reported for the first time. The liquid phase exchange of ligands fulfills the requirements of ink-jet printing processing for possible mass production. And the performance from ink-jet printed quantum dot light emitting diodes truly opens the gate of quantum dot light emitting diode application for industry.
关键词： quantum dot light emitting diodes,ink-jet printing,external quantum efficiency,dual ionic passivation,lifetime
更新于2025-09-23 15:21:01
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Inkjet printing a small-molecule binary emitting layer for organic light-emitting diodes
摘要： For inkjet-printed organic light-emitting diodes, it is critical to obtain a homogeneous small molecular-based emitting film. In contrast to the conventional strategy of utilizing mixed solvents, we have successfully inkjet printed a binary electrophosphorescent emitter with a single solvent. The binary emitter consists of a new host material of 3-(3,6-di-t-butylcarbazol-9-yl)-3'-(2-(4-t-butylphenyl)benzoimidazol-1-yl)-[1,1'-biphenyl], and an iridium complex dopant of bis(2-methyldibenzo[f,h]quinoxaline)(acetylacetonate)- iridium(III) (Ir(MDQ)2(acac)). Compatible with Ir(MDQ)2(acac), the newly developed host is highly soluble and amorphous with a glass transition temperature of 137 oC upon cooling from the melt. The inkjet printability and film morphology of the emitting layer are strongly dependent both on substrates and the solvents. With the o-dichlorobenzene (o-DCB) as the single solvent, and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4?-(N-(p-butylphenyl))diphenylamine)] (TFB) as the hole transporting layer, a uniform emitter film morphology without any coffee ring is obtained. The phosphorescent OLEDs with the inkjet-printed emitter yields a maximum current efficiency of 17.89 cd/A, comparable to that of the Ir(MDQ)2(acac)?based OLEDs with spin-cast emitter.
关键词： Dewetting,Coffee ring,Inkjet printing,Phosphorescent OLEDs,Small molecules
更新于2025-09-23 15:21:01
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[Laser Institute of America ICALEO?? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16a??20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Investigation of ablation characteristics for microrobotic materials using laser machining
摘要： Microrobotic devices have been widely investigated as promising alternatives to conventional biomedical technologies. By utilizing magnetic materials, microrobotic devices can be wirelessly manipulated by external magnetic fields without the use of additional power transfer units or batteries. Thus, the overall structures of the microrobotic devices can be effectively minimized to be applied for the human body. To manipulate the devices, various methods such as a magnetic force-based pulling method, cilia-like beating method, and helical propulsion method have been proposed. Conventional helical microrobotic devices have generally been manufactured by using three-dimensional (3D) printing technologies. These technologies are useful when manufacturing spatially complex structures such as the helical structures. However, due to the limitations of the extrusion and lamination processes, microrobotic devices can be constructed with low degree of precision and can have poor surface roughness under the 3D printing technologies. This may cause undesirable damages to the human body tissues. Furthermore, 3D printing requires long processing time due to post-processing to remove unwanted body parts. To improve surface quality and shorten processing time, this research uses laser machining technology. Before directly applying to fabricate helical microrobotic devices, laser ablation characteristics on Acrylonitrile Butadiene Styrene (ABS), which is a common material used for 3D printing, are investigated.
关键词： Acrylonitrile Butadiene Styrene (ABS),ablation characteristics,3D printing,laser machining,microrobotic devices
更新于2025-09-23 15:21:01
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Aerosol Jet Printed Optical Waveguides for Short Range Communication
摘要： This article presents an innovative way for additive manufacturing of optical multimode waveguides for short range data transmission. By the use of aerosol jet printing between conditioning lines on flexible foils, low cost and low weight polymer optical waveguides can be easily fabricated. The main advantages – compared to other waveguide manufacturing techniques – are the maximum fabricable waveguide length (not limited by panel- or wafer size), technology costs and 3D-ability. Furthermore, the printing allows for very long structures, which are not limited to wafer or panel sizes. In order to classify the new manufacturing approach and compare it to other technologies such as photolithography, imprinting, dispensing and ion-exchange, results on the mechanical (shear strength) and optical performance (transmittance, near field and attenuation) are presented. In addition, the experimental results on the data transmission performance are important to prove the suitability of the waveguides for high-speed communication applications. In this context, nearly error-free transmission up to 10 Gbit/s was achieved at a wavelength of 850 nm.
关键词： optical multimode waveguide,additive manufacturing,shear test,aerosol jet printing,optical data transmission
更新于2025-09-23 15:21:01
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Inkjeta??Printed TiO <sub/>2</sub> /Fullerene Composite Films for Planar Perovskite Solar Cells
摘要： Perovskite solar cells have garnered and held international research interest, due to ever-climbing power conversion efficiency values, now >25%. Some high efficiency configurations utilize a compact TiO2 layer underneath a mesoporous TiO2 layer, both of which require high temperature annealing steps that could hinder perovskite commercialization. To address the high thermal budget, we chose to use inkjet-printing to combine the two layers into a single TiO2 film, which incorporates both nanoparticle and molecular precursor as well as organic fullerene additives. We printed the ink on fluorine-doped tin oxide, and after annealing at various temperatures, we found that 400°C was the optimum annealing temperature for the inkjet-printed electron transport layers, which is significantly lower than the 500°C required to anneal typical mesoporous TiO2 films.
关键词： composite transport layer,inkjet printing,perovskite solar cells,solar cells
更新于2025-09-23 15:21:01
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Photoresins based on acrylated epoxidized soybean oil and benzenedithiols for optical 3D printing
摘要： The purpose of this paper is the design and investigation of novel acrylated epoxidized soybean oil-based photocurable systems as candidate materials for optical 3D printing. Aromatic dithiols, benzene-1,3-dithiol or benzene-1,4-dithiol, were used as cross-linking agents of acrylated epoxidized soybean oil in these systems. Kinetics of photocross-linking was investigated by real-time photorheometry using two different photoinitiators, 2, 2-dimethoxy-2-phenylacetophenone or 2-hydroxy-2-methylpropiophenone, in different quantities. The effect of the initial composition on the rate of photocross-linking, mechanical, thermal properties and swelling of obtained polymers was investigated. The rate of photocross-linking was higher, more cross-links and shorter polymer chains between cross-linking points of the network were formed when benzene-1,4-dithiol and 2, 2-dimethoxy-2-phenylacetophenone were used in compositions. The higher yield of insoluble fraction, glass transition temperatures and values of compressive modulus were obtained when benzene-1,3-dithiol and 2, 2-dimethoxy-2-phenylacetophenone were used in compositions. This is the first study of acrylated epoxidized soybean oil-based thiol-ene system by real-time photorheometry. The designed novel photocurable systems based on acrylated epoxidized soybean oil and benzenedithiols are promising renewable photoresins for rapid optical 3D printing on demand.
关键词： Photocross-linking,Thiol-ene,Optical 3D printing,Real-time photorheometry,Acrylated epoxidized soybean oil
更新于2025-09-23 15:21:01