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Rapid Alloy Development of Extremely High-Alloyed Metals Using Powder Blends in Laser Powder Bed Fusion
摘要： The design of new alloys by and for metal additive manufacturing (AM) is an emerging field of research. Currently, pre-alloyed powders are used in metal AM, which are expensive and inflexible in terms of varying chemical composition. The present study describes the adaption of rapid alloy development in laser powder bed fusion (LPBF) by using elemental powder blends. This enables an agile and resource-efficient approach to designing and screening new alloys through fast generation of alloys with varying chemical compositions. This method was evaluated on the new and chemically complex materials group of multi-principal element alloys (MPEAs), also known as high-entropy alloys (HEAs). MPEAs constitute ideal candidates for the introduced methodology due to the large space for possible alloys. First, process parameters for LPBF with powder blends containing at least five different elemental powders were developed. Secondly, the influence of processing parameters and the resulting energy density input on the homogeneity of the manufactured parts were investigated. Microstructural characterization was carried out by optical microscopy, electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS), while mechanical properties were evaluated using tensile testing. Finally, the applicability of powder blends in LPBF was demonstrated through the manufacture of geometrically complex lattice structures with energy absorption functionality.
关键词： multi-principal element alloys,high-entropy alloys,additive manufacturing,rapid alloy development,powder blends,laser powder bed fusion
更新于2025-11-21 11:01:37
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Semiconducting carbon nanotubes in photovoltaic blends: The case of pTB7:PC <sub/>60</sub> BM:(6,5) SWNT
摘要： Blends of carbon nanotubes with conjugated polymer and fullerene derivatives are complex nanocomposite systems, which have recently attracted great research interest for their photovoltaic ability. Therefore, gaining a better understanding of the excitonic dynamics in such materials can be important to boost the efficiency of excitonic solar cells. Here, we studied the photophysics of a ternary system in which the polymer PTB7 and the fullerene derivative PCBM are integrated with (6,5) single walled carbon nanotubes. We highlight the contribution of SWNTs in the exciton dissociation and in the charge transfer process. These findings can be useful for the exploitation of these multi-component systems for organic photovoltaic and, in general, optoelectronic applications.
关键词： excitonic dynamics,PCBM,photovoltaic blends,PTB7,SWNTs,carbon nanotubes
更新于2025-10-22 19:40:53
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Understanding the oxygen barrier property of highly transparent poly(lactic acid)/benzoxazine composite film by analyzing the UV-shielding performance
摘要： This work reports a new composite film from poly(lactic acid) (PLA) and benzoxazine (BOZ). Introduction of BOZ to PLA simultaneously improves the ultraviolet (UV)-shielding and oxygen barrier properties, which show strong dependence on the content of BOZ. The PLA film demonstrates almost no UV-shielding capacity, but the PLA/BOZ composite film can reach UV-shielding capacity of 98.3% at 350 nm. The corresponding average oxygen permeability coefficient of the composite film is as low as 1.168 × 10^{-18} m^3 m m^{-2} s^{-1} Pa^{-1}, which is significantly lower than that of PLA (5.540 × 10^{-17} m^3 m m^{-2} s^{-1} Pa^{-1}). Meanwhile, the composite film retains visible transparency ≥90.0% at 550 nm. The relationship and its implication between the oxygen barrier performance and UV-shielding capacity are discussed, which propose new guidelines for the development of high barrier PLA film.
关键词： thermosets,films,blends,thermoplastics
更新于2025-09-23 15:23:52
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Enhancement of photovoltaic performance in immiscible ternary blends
摘要： Ternary-blend active layers composed of one donor and two acceptors have been actively studied to enhance the power conversion efficiency (PCE) of organic solar cells (OSCs), and numerous advances in miscible ternary blends have been reported. In the present study, we report an unusual behavior of immiscible ternary blends with respect to the enhancement of PCE and stability of OSC devices. The active layer consists of three relatively easily synthesizable materials: poly[(4,8-bis(5-(2-ethylhexyl)thiophen2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl)-alt-((5-bromo-4-octylthiazol-2-yl)thiophene-2,5-diyl)] (POTz) as a donor, 2,2′-((2Z,2′Z)-((4,4,9,9-tetrahexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(methanylylidene))bis(3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (IDIC) as a nonfullerene acceptor, and [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) fullerene. The POTz:IDIC blends showed a typical bicontinuous and uniform nanomorphology; however, the addition of PC70BM to the POTz:IDIC blends led to immiscible domains. When small amounts of PC70BM (8.3–16.7 w%) were incorporated into POTz:IDIC:PC70BM blends, the POTz:IDIC formed a continuous phase and small PC70BM domains were uniformly dispersed into the continuous phase, which resembled raisin bread. The dispersed PC70BM domains enhanced the electron mobility of the POTz:IDIC:PC70BM film and promoted charge balance between holes and electrons, resulting in an enhanced short-circuit current density and fill factor. Notably, the ternary blends with PC70BM exhibited the improved long-term stability in light-soaking tests by reducing the burn-in loss of the devices.
关键词： semi-crystalline polymer,organic solar cells,continuous phase,immiscible blends,ternary blends
更新于2025-09-23 15:21:01
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Efficient, stable and high color rendering index white polymer light-emitting diodes by restraining the electron trapping
摘要： Superior solid-state light source should possess not only a high device efficiency but also high color rendering index (CRI) and excellent color stability. Here, we obtained efficient, stable and high CRI white polymer light-emitting diodes (WPLEDs) through applying the well-chosen trichromatic polymers and restraining the electron trapping. The trichromatic polymers all possess the similar mainchain units, their EL spectra shows an equidistant distribution. Detailed studies revealed that the part of green and red emission in the WPLED derive from the electron trapping which led to the current-dependent spectra. Applied proper electron transporting layer can enhance the direct electron injection which resulted in the electron trapping being restrained and improving the color stability. The optimized WPLED got a LEmax of 10.17 cd A-1 and CRI of 92, the CIE coordinates (0.346, 0.345) almost keep the same with the operating current density increasing from 10.53 mA cm-2 to 263.16 mA cm-2.
关键词： Electron trapping,Polymer blends,WPLED,Fluorescence
更新于2025-09-23 15:21:01
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Polymer functionalized nanoparticles in liquid crystals: combining PDLCs with LC nanocomposites
摘要： Liquid crystal (LC)–polymer blends are important stimuli responsive materials already employed in a wide range of applications whereas nanoparticle (NP)–LC blends are an emerging class of nanocomposites. Polymer ligands offer the advantages of synthetic simplicity along with chemical and molecular weight tunability. Here we compare the phase behavior of 5CB blended with poly(ethylene oxide) (PEO) and with gold NPs functionalized with thiolated PEO (AuNP–PEO) as a function of PEO concentration by DSC, POM and 13C NMR spectroscopy. Both PEO and the AuNP–PEO form uniform dispersions in isotropic 5CB and phase separate below the I–N phase transition temperature. Above the PEO crystallization temperature, the PEO/5CB blends show the expected biphasic state of PEO rich-isotropic liquid co-existing with PEO-poor nematic droplets. At PEO concentrations above 10 wt%, nematic 5CB nucleates with PEO crystallization. Both PEO and AuNP–PEO induce homeotropic alignment of the 5CB matrix immediately below TNI. The AuNP–PEO/5CB blends form thermally reversible cellular networks similar to AuNPs functionalized with low molecular weight mesogenic ligands. A thermodynamic model to account for the observed phase behavior is presented.
关键词： Polymer blends,Nanoparticles,Liquid crystal,Phase behavior,Thermodynamic model
更新于2025-09-23 15:21:01
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Octane prediction from infrared spectroscopic data
摘要： A model for the prediction of research octane number (RON) and motor octane number (MON) of hydrocarbon mixtures and gasoline-ethanol blends has been developed based on infrared spectroscopy data of pure components. Infrared spectra for 61 neat hydrocarbon species were used to generate spectra of 148 hydrocarbon blends by averaging the spectra of their pure components on a molar basis. The spectra of 38 FACE (Fuels for Advanced Combustion Engines) gasoline blends were calculated using PIONA (Paraffin, Isoparaffin, Olefin, Naphthene, and Aromatic) class averages of the pure components. The study sheds light on the significance of dimensional reduction of spectra and shows how it can be used to extract scores with linear correlations to the following important features: molecular weight, paraffinic CH3 groups, paraffinic CH2 groups, paraffinic CH groups, olefinic -CH=CH2 groups, naphthenic CH-CH2 groups, aromatic C-CH groups, ethanolic OH groups, and branching index. Both scores and features can be used as input to predict octane numbers through nonlinear regression. Artificial Neural Network (ANN) was found to be the optimal method where the mean absolute error on a randomly selected test set was within the experimental uncertainty of RON, MON, and octane sensitivity.
关键词： octane prediction,infrared spectroscopy,hydrocarbon blends,artificial neural network,gasoline-ethanol blends,dimensional reduction
更新于2025-09-19 17:13:59
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Hole Transfer Promoted by a Viscosity Additive in an All-Polymer Photovoltaic Blend
摘要： Viscosity modi?ers are widely applied to improve the mechanical compliance of organic optoelectronic devices. However, the e?ect of the viscosity additives on the charge dynamics remains poorly understood. Here, we report the observation of markedly di?erent e?ects of a high-viscosity polymeric additive on the electron- and hole-transfer dynamics in all-polymer organic photovoltaic blends. By using ultrafast transient absorption spectroscopy, we determine that hole transfer from charge-transfer excitations in the acceptor is markedly promoted while the electron transfer from local excitations in the donor remains nearly unchanged upon introduction of viscosity additives into the blends. We argue that the modi?cation of dielectric screening is the mechanism underlying the e?ect of the additive on the charge dynamics. This ?nding suggests a new strategy for designing high-performance ?exible organic photovoltaic devices by manipulating the dielectric environment.
关键词： electron transfer,hole transfer,viscosity additives,dielectric screening,all-polymer photovoltaic blends
更新于2025-09-19 17:13:59
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Light Harvesting at Oblique Incidence Decoupled from Transmission in Organic Solar Cells Exhibiting 9.8% Efficiency and 50% Visible Light Transparency
摘要： For many years, it has been recognized that potential organic photovoltaic cells must be integrated into elements requiring high transparency. In most of such elements, sunlight is likely to be incident at large angles. Here it is demonstrated that light transmission can be largely decoupled from harvesting by optically tailoring an infrared shifted nonfullerene acceptor based organic cell architecture. A 9.67% power conversion efficiency at 50° incidence is achieved together with an average visual transmission above 50% at normal incidence. The deconstruction of a 1D nanophotonic structure is implemented to conclude that just two λ/4 thick layers are essential to reach, for a wide incidence angle range, a higher than 50% efficiency increase relative to the standard configuration reference. In an outdoor measurement of vertically positioned 50% visible transparent cells, it is demonstrated that 9.80% of sunlight energy can be converted into electricity during the course of 1 day.
关键词： transparent solar cells,near-infrared ternary blends,1-D nanophotonic structures,optical trapping,oblique incidence
更新于2025-09-19 17:13:59
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Coupled photothermal and joule-heating process for stable and efficient interfacial evaporation
摘要： A trade-off inevitably exists between soot and NOX emissions in a traditional engine. The addition of an oxygen-containing biofuel can decrease the soot emission but increase the NOX emission. Multi-injection strategy can be used to decrease the NOX emission. Therefore, both simulations and experimental tests were conducted to evaluate the influences of pre-injection on the combustion and emission characteristics of pure diesel (D100) and diesel/n-butanol (30% n-butanol and 70% diesel by volume, B30). The results showed that as the pre-injection interval decreased, the in-cylinder pressure peak increased, the pre-injection heat release ratio increased, and the brake-specific fuel consumption (BSFC) decreased. Only at a small pre-injection interval, the BSFC under pre-injection condition was lower than that obtained using the single injection strategy. When the same pre-injection strategy was used, B30 had a higher BSFC and lower brake thermal efficiency than D100. The soot emission decreased with the increase in pre-injection interval but increased with the increase in pre-injection ratio. More soot was emitted using the pre-injection strategy than that using single injection strategy. B30 had a lower soot emission than D100 due to a longer ignition delay. As the pre-injection interval increased, the decreasing amplitude of NO production became smaller than the increasing amplitude of NO2 production, thus increasing the net NOX emission. As the pre-injection ratio increased, more CO was produced through the reaction paths CH2O → HCO → CO, whereas the transformation of CO to CO2 almost remained unchanged, thus increasing the net CO emission. The increase in pre-injection ratio inhibited the oxidation of CO to CO2 and thus increased the CO emission. The amount of unburned hydrocarbons increased with the increase in both pre-injection ratio and interval.
关键词： Chemical kinetics,CFD,Pre-injection,Diesel/n-butanol blends,Low-temperature combustion
更新于2025-09-16 10:30:52