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排序方式: 共有108条查询结果,搜索用时 437 毫秒
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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
3.
A Thieno[3,2‐b][1]benzothiophene Isoindigo Building Block for Additive‐ and Annealing‐Free High‐Performance Polymer Solar Cells 下载免费PDF全文
4.
R. Pacios A.J. Chatten K. Kawano J.R. Durrant D.D.C. Bradley J. Nelson 《Advanced functional materials》2006,16(16):2117-2126
A study of the photo‐oxidation of films of poly[2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylene vinylene] (MDMO‐PPV) blended with [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM), and solar cells based thereon, is presented. Solar‐cell performance is degraded primarily through loss in short‐circuit current density, JSC. The effect of the same photodegradation treatment on the optical‐absorption, charge‐recombination, and charge‐transport properties of the active layer is studied. It is concluded that the loss in JSC is primarily due to a reduction in charge‐carrier mobility, owing to the creation of more deep traps in the polymer during photo‐oxidation. Recombination is slowed down by the degradation and cannot therefore explain the loss in photocurrent. Optical absorption is reduced by photo‐bleaching, but the size of this effect alone is insufficient to explain the loss in device photocurrent. 相似文献
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Abigail Durrant David S. Kirk Steve Benford Tom Rodden 《Computer Supported Cooperative Work (CSCW)》2012,21(1):43-79
In this paper, we present the theme park as a novel commercial setting and distinct cultural ecology for CSCW research, presenting
challenges to technology designers interested in supporting cultural visiting activities. We report findings from an empirical
field study of theme park visiting by groups. Our account focuses on how visitors encountered the theme park, and how they
worked with or “geared in” to what the park provided in order to pursue leisure activities to their own ends. We further demonstrate
that, whilst theme park visiting features thrilling and fun activities, it also features the prosaic concerns of planning,
parenting and money that connect it to ordinary social life. As such, we present the theme park as a setting in which work
and leisure are intertwined as concerns of both visitors and the park, for producing and consuming theme park experience.
We have focussed on the work of visiting groups to pursue leisure, and their combined use of park-provided and personal technologies
in various “trajectories of interaction” within the park. Our findings point to considerations for the design of services
that connect with park-provided and personal technologies to support group visiting, in theme parks and related settings. 相似文献
8.
J. X. Dong P. A. Karnezis G. Durrant B. Cantor 《Metallurgical and Materials Transactions A》1999,30(5):1341-1356
This article describes the results of an investigation into the microstructure and mechanical properties of a gravity die
cast and direct squeeze cast LM25 alloy (Al-7Si-0.3Mg-0.3Fe). The direct squeeze cast LM25 alloy has superior mechanical properties
compared to the gravity die cast LM25 alloy, especially with regard to ductility, which is increased from ∼1.7 pct for the
gravity die cast LM25 alloy to ∼8.0 pct for the direct squeeze cast LM25 alloy in the T6 heat-treated condition. This increase
in ductility is due to (1) the removal of porosity, (2) a decrease in Si particle size, and (3) a refinement of the Fe-Si-aluminide
particles. High cooling rates in direct squeeze casting result in quench modification of the Si particles, such that chemical
modification with Sr or Na may not be required. In addition, direct squeeze casting is more tolerant of Fe impurities in the
alloy, due to the formation of smaller Fe-Si-aluminide particles than those in gravity die cast material. The direct squeeze
cast LM25+Fe alloy (Al-7Si-0.3Mg-1.0Fe) has a ductility of ∼6.5 pct, compared to that of ∼0.5 pct for the gravity die cast
LM25 + Fe alloy in the T6 heat-treated condition. This increase in tolerance to Fe impurities can lead to a substantial reduction
in manufacturing costs due to (1) reduced raw-material costs, (2) reduced die sticking, and (3) improved die life. 相似文献
9.
Degradation of organic solar cells due to air exposure 总被引:1,自引:0,他引:1
Kenji Kawano Roberto Pacios Dmitry Poplavskyy Jenny Nelson Donal D.C. Bradley James R. Durrant 《Solar Energy Materials & Solar Cells》2006,90(20):3520-3530
We present a study of dark air-exposure degradation of organic solar cells based on photoactive blends of the conjugated polymer, poly[2-methoxy-5-(3′,7′-dimethyloctyloxy)-1,4-phenylene vinylene] (MDMO-PPV) with [6,6]-phenyl C61-butyric acid methyl ester (PCBM). Photovoltaic devices were fabricated on indium tin oxide (ITO) glass with or without a layer of poly (3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS), and were studied without encapsulation. Photovoltaic performance characteristics were measured as a function of time for different ambient conditions (under white light irradiation and in the dark, and under air, dry oxygen and humid nitrogen atmospheres). It was found that a key cause of degradation under air exposure is light independent and results from water adsorption by the hygroscopic PEDOT:PSS layer. Measurements of the charge mobility and hole injection after air exposure showed that the degradation increases the resistance of the PEDOT:PSS/blend layer interface. 相似文献
10.
Dan Credgington Rick Hamilton Pedro Atienzar Jenny Nelson James R. Durrant 《Advanced functional materials》2011,21(14):2744-2753
The physical origin of the open‐circuit voltage in bulk heterojunction solar cells is still not well understood. While significant evidence exists to indicate that the open‐circuit voltage is limited by the molecular orbital energies of the heterojunction components, it is clear that this picture is not sufficient to explain the significant variations which often occur between cells fabricated from the same heterojunction components. We present here an analysis of the variation in open‐circuit voltage between 0.4–0.65 V observed for a range of P3HT/PCBM solar cells where device deposition conditions, electrode structure, active‐layer thickness and device polarity are varied. The analysis quantifies non‐geminate recombination losses of dissociated carriers in these cells, measured under device operating conditions. It is found that at open‐circuit, losses due to non‐geminate recombination are sufficiently large that other loss pathways may effectively be neglected. Variations in open‐circuit voltage between different devices are shown to arise from differences in the rate coefficient for non‐geminate recombination, and from differences in the charge densities in the photoactive layer of the device. The origin of these differences is discussed, particularly with regard to variations in film microstructure. By separately quantifying these differences in rate coefficient and charge density, and by application of a simple physical model based upon the assumption that open‐circuit is reached when the flux of charge photogeneration is matched by the flux of non‐geminate recombination, we are able to calculate correctly the open‐circuit voltage for all the cells studied to within an accuracy of ±5 mV. 相似文献