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Efficient organic solar cells with superior stability based on PM6:BTP-eC9 blend and AZO/Al cathode
No full textAlthough efficiency over 18% has been achieved, the real application of organic solar cells is still impeded by inferior stability because of degradation and limited studies. Here we report efficient normal structure organic solar cells delivering promising stability under different conditions, based on PM6:BTP-eC9 blend and AZO/Al cathode. The impact of cathode on device stability is systematically studied by screening the leading electron transporting layers i.e., AZO, PFN-Br, PDINN, and metal electrodes (Al and Ag). Strong correlation between cathode and stability is demonstrated. The optimal AZO/Al-cathode device delivers the best efficiency of 15.76%, with shelf-stability of T83 > 1,200 h, thermal stability of T60 > 300 h, and MPP operational stability of T87 > 500 h. As far as we know, this is the best stability achieved for PM6:Y6/derivative cells in literature so far, based on well-studied simple cathode system and without any tailoring/dopant for the active blend
Enhanced interface interaction in Cu2S@Ni core-shell nanorod arrays as hydrogen evolution reaction electrode for alkaline seawater electrolysis
No full textExploring cheap, efficient and stable electro-catalysts for hydrogen evolution reaction (HER) is a vital technology for seawater splitting development. Herein, we demonstrate that constructing underlying Cu2S nanorod arrays is crucial for improving the HER activity of surface Ni catalyst. Electrochemical results reveal that nickel coated Cu2S nanoarrays (Cu2S@Ni) on copper foam exhibits a preferable HER activity (similar to 500 mA cm(-2) at <200 mV overpotential), outperforming Cu2O@Ni and pure Ni counterparts. Detailed analyses indicate that the enhanced HER activity of Cu2S@Ni can be attributed to Ni-S interaction between surface nickel and underlying Cu2S nanorods, which optimizes the adsorption energy of hydrogen on the surface. Moreover, the Cu2S@Ni nanoarray electrode shows a remarkable HER stability, highlighting its promising potential in alkaline seawater electrolysis
Ga-doped Czochralski silicon with rear p-type polysilicon passivating contact for high-efficiency p-type solar cells
No full textThe use of Ga-doped Czochralski (CZ) silicon wafers in Passivated Emitter and Rear Cells (PERC) has been confirmed to have a prominent advantage in suppressing light-induced degradation (LID), which will attract considerable attention for the application of Ga-doped wafers in more efficient photovoltaic devices. In this work, we investigate the passivation quality and address the issue of LID in Ga-doped CZ Si wafers equipped with p-type polysilicon passivating contact that consists of an ultrathin SiOx and a heavily doped polysilicon. We also present the modeling results for solar cells using this type of contact. The experiments show that samples with Ga-doped CZ Si wafers have superior anti-LID properties when compared to the samples with B-doped wafers. An excellent passivation performance with a high implied open-circuit voltage (iV(oc)) of 705 mV and a low singlesided saturation current density (J(0,s)) of 9 fA/cm(2) was achieved. Moreover, with the help of the numerical simulations, we predict that the p-type Ga-doped CZ Si solar cells with p-type polysilicon passivating contacts have the potential to achieve a high efficiency of 23.8%, an similar to 0.5% absolute efficiency improvement over that of PERC solar cells. The results demonstrated in this study suggest that Ga-doped CZ Si wafers combined with p-type polysilicon passivating contacts could resolve the LID issue while maintaining good passivation properties, providing a promising alternative for p-type solar cells in the photovoltaic industry
A novel design by constructing MoS2/WS2 multilayer film doped with tantalum toward superior friction performance in multiple environment
No full textTransition metal dichalcogenides (TMDs) are easily oxidized in the humid atmosphere, leading to a decrease in their lubricating properties and limiting their application. In this study, a MoS2/WS2 multilayer film doped with tantalum (MoS2/WS2-Ta) is fabricated by magnetron sputtering to improve the corrosion and oxidation resistance of TMDs. Results show that doping of Ta makes the structure of the MoS2/WS2 multilayer film more compact, and the MoS2 and WS2 crystals exhibit a stronger (0002) preferred orientation than that of un-doped sample. Such compact structure and (0002) preferred orientation of MoS2/WS2-Ta can realize a high corrosion resistance, i.e., a more positive corrosion potential and a lower corrosion current density in comparison with the MoS2/WS2 multilayer. Furthermore, the friction properties of MoS2/WS2 multilayer film doped with 1.1 at% of Ta are improved remarkably under both of high temperature (370 degrees C in air) and vacuum conditions, the result is attributed to its high mechanical properties and (0002) preferred orientation. In a word, the combination of multilayer structure and doping of Ta into the films is a promising approach to accurately design the TMDs toward a wide temperature range and environmentally adaptive lubricants. [GRAPHICS]
Rapid-Thermal-Annealing-Induced Passivation Degradation and Recovery of Polysilicon Passivated Contact with Czochralski and Cast Multicrystalline Silicon Substrates
No full textMetallization of high-efficiency n-type solar cells with tunnel oxide passivated contact (TOPCon) structures often requires a high-temperature rapid-thermal-annealing (RTA) process, which potentially induces a notable degradation of device performance. Herein, the RTA-induced passivation degradation mechanisms and potential recovery processes are clarified by postthermal annealing or hydrogenation based on both Czochralski (Cz) silicon and cast-multicrystalline (cast-mc) silicon wafers. It is found that the RTA process induces at least two kinds of defects, i.e., thermal-quenching-induced defects and hydrogen-release-induced defects. The passivation quality can be partially recovered under a high-temperature annealing at 820 degrees C, which, however, can be fully restored via a postmoisture/nitrogen hydrogenation treatment at 450 degrees C. In general, the two mentioned wafers, i.e., n-type Cz c-Si and cast-mc silicon substrates, demonstrate similar passivation behaviors in most cases before and after RTA treatment. Finally, it is inferred that the inferior passivation properties of the n-type cast-mc silicon samples are related to the relatively low bulk quality. This can be confirmed by the fact that samples with n-type cast-mc Si substrates show an abnormal passivation behavior with highly effective lifetimes in the low-density carrier region, suggesting the existence of electron trapping states
Original Research Paper Synthetic anti-angiogenic genomic therapeutics for treatment of neovascular age-related macular degeneration
No full textIn light of the intriguing potential of anti-angiogenic approach in suppressing choroidal neovascularization, we attempted to elaborate synthetic gene delivery systems encapsulating anti-angiogenic plasmid DNA as alternatives of clinical antibody-based therapeutics. Herein, block copolymer of cyclic Arg-Gly-Asp-poly(ethylene glycol)poly(lysine-thiol) [RGD-PEG-PLys(thiol)] with multifunctional components was tailored in manufacture of core-shell DNA delivery nanoparticulates. Note that the polycationic PLys segments were electrostatically complexed with anionic plasmid DNA into nanoscaled core, and the tethered biocompatible PEG segments presented as the spatial shell (minimizing non-specific reactions in biological milieu). Furthermore, the aforementioned self-assembly was introduced with redox-responsive disulfide crosslinking due to the thiol coupling. Hence, reversible stabilities, namely stable in extracellular milieu but susceptible to disassemble for liberation of the DNA payloads in intracellular reducing microenvironment, were verified to facilitate transcellular gene transportation. In addition, RGD was installed onto the surface of the proposed self-assemblies with aim of targeted accumulation and internalization into angiogenic endothelial cells given that RGD receptors were specifically overexpressed on their cytomembrane surface. The proposed anti-angiogenic DNA therapeutics were validated to exert efficient expression of anti-angiogenic proteins in endothelial cells and elicit potent inhibition of ocular neovasculature post intravitreous administration. Hence, the present study approved the potential of gene therapy in treatment of choroidal neovascularization. In light of sustainable gene expression properties of DNA therapeutics, our proposed synthetic gene delivery system inspired prosperous potentials in long-term treatment of choroidal neovascularization, which should be emphasized to develop further towards clinical translations. (C) 2021 Shenyang Pharmaceutical University. Published by Elsevier B.V
Ultrafine-grained Zn-0.45Li alloy with enhanced mechanical property, degradation behavior and cytocompatibility prepared by hot extrusion and multi-pass drawingUltrafeinkornige durch Heissextrusion und Mehrfachzug hergestellte Zn-0,45Li-Legierung mit verbesserten mechanischen Eigenschaften, Abbauverhalten und Zytokompatibilitat
No full textBiodegradable Zn-0.45Li alloys with high strength and ductility were successfully fabricated by hot extrusion and multi-pass drawing to obtain ultrafine-grained microstructures with a secondary phase of fine LiZn4 participates. The mechanical properties, degradation behavior and cytocompatibility of the alloys were subsequently investigated. Results showed that grain refinement could be achieved in the alloys after hot extrusion and multi-pass drawing. The yield strength, ultimate tensile strength, and elongation to failure of the ultrafine-grained Zn-0.45Li alloys reached 416 MPa, 567 MPa and 55.4 %, respectively. Enhancements in both strength and elongation could be attributed to interactions between LiZn4 and matrix dislocations, the pinning effect of LiZn4 on grain boundaries, and grain refinement. Immersion tests and MTT cytotoxicity assay indicated that the Zn-0.45Li alloys have a corrosion rate and cytocompatibility similar to the values reported for biomedical implants
Compact CubeSat Gamma-ray detector for GRID mission
No full textGamma-Ray Integrated Detectors (GRID) mission is a student project designed to use multiple gamma-ray detectors carried by nanosatellites (CubeSats), forming a full-time all-sky gamma-ray detection network that monitors the transient gamma-ray sky in the multi-messenger astronomy era. A compact CubeSat gamma-ray detector, including its hardware and firmware, was designed and implemented for the mission. The detector employs four Gd2Al2Ga3O12 : Ce (GAGG:Ce) scintillators coupled with four silicon photomultiplier (SiPM) arrays to achieve a high gamma-ray detection efficiency between 10 keV and 2 MeV with low power and small dimensions. The first detector designed by the undergraduate student team onboard a commercial CubeSat was launched into a Sun-synchronous orbit on October 29, 2018. The detector was in a normal observation state and accumulated data for approximately one month after on-orbit functional and performance tests, which were conducted in 2019
Enhanced magnetic softness of surface-crystallized Fe-Si-B-Nb-Mo-Cu amorphous alloys via competitive growth of surface pre-crystals/clusters
No full textThe deterioration of magnetic softness caused by surface crystallization is a common problem in Fe-based amorphous and nanocrystalline alloys. However, we found that the surface crystallization of Fe76Si13B8Nb2xMoxCu1 (x = 0,1,2) amorphous alloys has negligible effects on the onset precipitation temperature, nucleation, and growth activation energy of alpha-Fe(Si) phase, thus forming a nanocrystalline structure similar to that of the fully amorphous sample after proper heat treatment. The ultrafine nano-grains uniformly precipitated in the ribbons due to the competitive growth of numerous tiny pre-crystals/clusters near the surface and the internal grain refinement caused by refractory elements, which helps to form regular magnetic domains, thereby good magnetic softness comparable to that of the fully amorphous sample was obtained. This work provides guidance for eliminating the deteriorating effect of surface crystallization on magnetic properties and expanding the industrial application of surface-crystallized Fe-based amorphous alloys
Additive Manufacturing of Polyamide 66: Effect of Process Parameters on Crystallinity and Mechanical Properties
No full textIn this study, polyamide 66 (PA 66) filaments were prepared for fused filament fabrication (FFF). The effects of the process parameters on the mechanical properties, initial microstructures, dynamic mechanical behavior, and crystallinity of the samples were investigated. The samples obtained at high processing temperatures exhibited high crystallinity, high tensile strength, and low porosity. Almost fully dense samples with excellent mechanical properties were obtained under optimal conditions. The tensile strength of the samples improved by 29.5% (from 68.07 to 88.17 MPa) with an increase in the nozzle temperature from 270 to 290 degrees C. The elongation at break abruptly increased (from 2.38 to 13.17%), because of the plastic behavior of the material and strain hardening. X-ray diffraction results demonstrated that the crystallinity of PA 66, significantly improved (from 47.3 to 65.6%). In addition, the dynamic mechanical performance of the samples was significantly related to the raster angle. The samples fabricated at a raster angle of 0 degrees exhibited the best dynamic mechanical properties, followed by the 45 degrees and 90 degrees samples. The successful fabrication of PA 66 samples demonstrates the potential use of PA 66 for producing parts using FFF, and provides options for utilizing materials with improved performance for additive manufacturing applications in engineering