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151.
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P. Ravirajan S.A. Haque J.R. Durrant D.D.C. Bradley J. Nelson 《Advanced functional materials》2005,15(4):609-618
We report a study of the effects of polymer optoelectronic properties on the performance of photovoltaic devices consisting of nanocrystalline TiO2 and a conjugated polymer. Three different poly(2‐methoxy‐5‐(2′‐ethylhexoxy)‐1,4‐phenylenevinylene) (MEH‐PPV)‐based polymers and a fluorene–bithiophene copolymer are compared. We use photoluminescence quenching, time‐of‐flight mobility measurements, and optical spectroscopy to characterize the exciton‐transport, charge‐transport, and light‐harvesting properties, respectively, of the polymers, and correlate these material properties with photovoltaic‐device performance. We find that photocurrent is primarily limited by the photogeneration rate and by the quality of the interfaces, rather than by hole transport in the polymer. We have also studied the photovoltaic performance of these TiO2/polymer devices as a function of the fabrication route and device design. Including a dip‐coating step before spin‐coating the polymer leads to excellent polymer penetration into highly structured TiO2 networks, as was confirmed through transient optical measurements of the photoinduced charge‐transfer yield and recombination kinetics. Device performance is further improved for all material combinations studied, by introducing a layer of poly(ethylene dioxythiophene) (PEDOT) doped with poly(styrene sulfonic acid) (PSS) under the top contact. Optimized devices incorporating the additional dip‐coated and PEDOT:PSS layers produced a short‐circuit current density of about 1 mA cm–2, a fill factor of 0.50, and an open‐circuit voltage of 0.86 V under simulated AM 1.5 illumination (100 mW cm–2, 1 sun). The corresponding power conversion efficiency under 1 sun was ≥ 0.4 %. 相似文献
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In-situ composites based on dispersed poly (ethylene terephthalate) (PET) or polyamide (PA),and continuous Polyethylene (PE) were prepared through a single screw extruder of Haake rheometer system with a rod-die relatively small in diameter.The extrudate was drawn at a drawing ratio of 3.1,and then quickly cooled in cold water.The specimens were obtained by injection molding at processing temperatures less than 190℃,far below the melting temperature of PET (265℃) and PA (230℃),which can maintain the solid state of PET and PA microfiber phase in the composites.Morphological observation with scanning electron microscopy (SEM) indicated that PET and PA can more or less form in-situ microfibers at compositions studied (0-20 wt pct PET or PA),and especially,PET and PA were almost deformed into fibers at the concentration of 15wt pct.Eensile strength and especially.PET and PA were almost deformed into fibers at the concentration of 15wt pct.Tensile strength and modulus of the blends reinforced by PET or PA microfibers showed to be increased from the tensile test results.The most noticeable improvement of the tensile properties occurred at 15wt pct of PET in PET/PE system,corresponding to the highest microfiber content,where the tensile strength reached 32.5 MPa,whereas only 19.5 MPa for the pure PE. 相似文献
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镀液中SiC含量和粒径对Ni-P-SiC复合化学镀层性能的影响 总被引:7,自引:0,他引:7
采用化学镀方法制备了Ni P SiC复合镀层 ,系统研究了镀液中SiC含量和粒径对镀层结构及显微硬度的影响。结果表明 ,镀层中SiC析出量随镀液中SiC含量的增加而增加 ,在SiC含量一定的情况下 ,当SiC粒径为 7.0 μm时 ,析出量最大 ;镀液中SiC的含量和粒度对原始镀层的硬度影响不大 ,但对 4 0 0℃热处理后的镀层硬度有显著影响 相似文献
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WC对铜基和镍基喷焊覆层材料耐气蚀性能的影响 总被引:2,自引:0,他引:2
在CuNiSiB,NiCrSiB自熔合金粉末中添加WC陶瓷颗粒,利用氧乙炔焰粉末喷焊工艺制备覆层材料,用超声波振动气蚀仪对覆层材料进行耐气蚀性能研究,用扫描电子显微镜对覆层材料表面气蚀破坏形貌进行观察,结果表明:复合覆层材料的耐气蚀能力比基体强;提高CuNiSiB覆层材料耐气蚀能力的途径是强化晶界,还探讨了覆层材料的气蚀破坏机理。 相似文献