The performance of three wireless local-area network(WLAN) media access control(MAC) protocols is investigated and compared in the context of simulcast radioover-fiber-based distributed antenna systems(RoF-DASs) where...The performance of three wireless local-area network(WLAN) media access control(MAC) protocols is investigated and compared in the context of simulcast radioover-fiber-based distributed antenna systems(RoF-DASs) where multiple remote antenna units(RAUs) are connected to one access point(AP) with different-length fiber links.The three WLAN MAC protocols under investigation are distributed coordination function(DCF) in basic access mode,DCF in request/clear to send(RTS/CTS) exchange mode,and point coordination function(PCF).In the analysis,the inter-RAU hidden nodes problems and fiber-length difference effect are both taken into account.Results show that adaptive PCF mechanism has better throughput performances than the other two DCF modes,especially when the inserted fiber length is short.展开更多
Photovoltaic performance of the organic solar cells （OSCs） based on 2-（（5＇-（4-（（4-（（E）-2-（5＇-（2,2-dicyanovinyl）-3＇,4-dihexyl- 2,2＇-bithiophen-5-yl）vinyl） phenyl）（phenyl）amino）styryl）-4~4＇-dihe...Photovoltaic performance of the organic solar cells （OSCs） based on 2-（（5＇-（4-（（4-（（E）-2-（5＇-（2,2-dicyanovinyl）-3＇,4-dihexyl- 2,2＇-bithiophen-5-yl）vinyl） phenyl）（phenyl）amino）styryl）-4~4＇-dihexyl-2,2＇-bithiophen-5-yl）methylene）malononitrile （L（TPA- bTV-DCN）） as donor and PC70BM as acceptor was optimized using 0.25 vol% high boiling point solvent additive of 1-chloronaphthalene （CN）, 1,6-hexanedithiol （HDT）, or 1,8-diodooctane （DIO）. The optimized OSC based on L（TPA-bTV- DCN）-PC70BM （1：2, w/w） with 0.25 vol% CN exhibits an enhanced power conversion efficiency （PCE） of 2.61%, with Voc of 0.87 V, Jsc of 6.95 mA/cm2, and FF of 43.2%, under the illumination of 100 mW/cm2 AM 1.5 G simulated solar light, whereas the PCE of the OSC based on the same active layer without additive is only 1.79%. The effect of the additive on absorption spectra and the atomic force microscopy images of L（TPA-bTV-DCN）-PCv0BM blend films were further investigated. The improved efficiency of the device could be ascribed to the enhanced absorption and optimized domain size in the L（TPA-bTV-DCN）-PC70BM blend film.展开更多
An appropriate diameter and wire-to-wire dis- tance is critical for optimizing the performance of hybrid inorganic/organic photovoltaic devices. For a deep under- standing of their influences on such hybrid structures...An appropriate diameter and wire-to-wire dis- tance is critical for optimizing the performance of hybrid inorganic/organic photovoltaic devices. For a deep under- standing of their influences on such hybrid structures, the well-ordered ZnO nanowires with different diameters are fabricated by the versatile hydrothermal growth. The dependence of the photovoltaic performance on the surface states, wire diameter and wire-to-wire distance is investi- gated. We demonstrate that the pristine thick ZnO nanowires film possess a higher surface photovoltage （SPV） response than the thin one. This is mainly due to the influence of surface states on the thin ZnO nanowires, which can capture the photo-generated carriers. When the two kinds of ZnO nanowires are fabricated into a hybrid inorganic/organic structure, the thin ZnO nanowires/poly（3-hexylthiophene） hybrid film has a higher SPV response than the thick one, which is contrary to the pristine ZnO nanowires. This is benefited from the smaller diameter and wire-to-wire dis- tance of the thin ZnO nanowires owned. The crystallinity, wire diameter and wire-to-wire distance have the crucial influence on the final photovoltaic performance. The results shown here give us insights toward designing efficient hybrid photovoltaic devices.展开更多
基金supported in part by National 973 Program(2012CB315705)NSFC Program(61302086,61271042,61107058, 61302016,and 61335002)+2 种基金Specialized Research Fund for the Doctoral Program of Higher Education(20130005120007)Program for New Century Excellent Talents in University(NCET-13-0682)Fundamental Research Funds for the Central Universities
文摘The performance of three wireless local-area network(WLAN) media access control(MAC) protocols is investigated and compared in the context of simulcast radioover-fiber-based distributed antenna systems(RoF-DASs) where multiple remote antenna units(RAUs) are connected to one access point(AP) with different-length fiber links.The three WLAN MAC protocols under investigation are distributed coordination function(DCF) in basic access mode,DCF in request/clear to send(RTS/CTS) exchange mode,and point coordination function(PCF).In the analysis,the inter-RAU hidden nodes problems and fiber-length difference effect are both taken into account.Results show that adaptive PCF mechanism has better throughput performances than the other two DCF modes,especially when the inserted fiber length is short.
基金supported by the National Basic Research Program of China(2014CB643501)the National Natural Science Foundation of China(91333204)the support from Ministry of Education and Jiangsu Province(20100092120037,XNY-48-037)
文摘Photovoltaic performance of the organic solar cells （OSCs） based on 2-（（5＇-（4-（（4-（（E）-2-（5＇-（2,2-dicyanovinyl）-3＇,4-dihexyl- 2,2＇-bithiophen-5-yl）vinyl） phenyl）（phenyl）amino）styryl）-4~4＇-dihexyl-2,2＇-bithiophen-5-yl）methylene）malononitrile （L（TPA- bTV-DCN）） as donor and PC70BM as acceptor was optimized using 0.25 vol% high boiling point solvent additive of 1-chloronaphthalene （CN）, 1,6-hexanedithiol （HDT）, or 1,8-diodooctane （DIO）. The optimized OSC based on L（TPA-bTV- DCN）-PC70BM （1：2, w/w） with 0.25 vol% CN exhibits an enhanced power conversion efficiency （PCE） of 2.61%, with Voc of 0.87 V, Jsc of 6.95 mA/cm2, and FF of 43.2%, under the illumination of 100 mW/cm2 AM 1.5 G simulated solar light, whereas the PCE of the OSC based on the same active layer without additive is only 1.79%. The effect of the additive on absorption spectra and the atomic force microscopy images of L（TPA-bTV-DCN）-PCv0BM blend films were further investigated. The improved efficiency of the device could be ascribed to the enhanced absorption and optimized domain size in the L（TPA-bTV-DCN）-PC70BM blend film.
文摘An appropriate diameter and wire-to-wire dis- tance is critical for optimizing the performance of hybrid inorganic/organic photovoltaic devices. For a deep under- standing of their influences on such hybrid structures, the well-ordered ZnO nanowires with different diameters are fabricated by the versatile hydrothermal growth. The dependence of the photovoltaic performance on the surface states, wire diameter and wire-to-wire distance is investi- gated. We demonstrate that the pristine thick ZnO nanowires film possess a higher surface photovoltage （SPV） response than the thin one. This is mainly due to the influence of surface states on the thin ZnO nanowires, which can capture the photo-generated carriers. When the two kinds of ZnO nanowires are fabricated into a hybrid inorganic/organic structure, the thin ZnO nanowires/poly（3-hexylthiophene） hybrid film has a higher SPV response than the thick one, which is contrary to the pristine ZnO nanowires. This is benefited from the smaller diameter and wire-to-wire dis- tance of the thin ZnO nanowires owned. The crystallinity, wire diameter and wire-to-wire distance have the crucial influence on the final photovoltaic performance. The results shown here give us insights toward designing efficient hybrid photovoltaic devices.
