1,720,969 research outputs found
Study of Organic Polymer/Inorganic Semiconductor Hybrid Solar Cells in Inverted Structure
No full text有機太陽能電池具有質輕、可撓曲且在大面積下製作可以有較低的成本，近年來引起廣大的注意。在本論文中，我們使用PV2000做為倒置結構元件的主動層，比起P3HT/PCBM系統能提供較大的開路電壓。首先我們嘗試使用後退火處理來改善元件效率，藉由熱引發主動層型態的改善以及界面缺陷的修補，在這邊我們能發現後退火處理對於此元件的重要性。接著我們利用溶液製程的方式將金屬氧化物氧化鎳（稱作電子阻擋層/電洞傳輸層）旋轉塗佈在主動層上面，利用其較高的最低分子未佔據軌域，來阻擋電子直接傳輸到陽極與收集到此處的電洞進行復合，減少元件的漏電流產生增加元件的填充因子，進而提升反向結構元件之效率。當二氧化鈦奈米柱添加後，光吸收以及光電流的改善是顯而易見的，我們可以歸納出以下功能。第ㄧ,使主動層變厚從200nm提升至280nm，因此增加光吸收，使得光電流能有效提升。第二，其奈米結構型態能提供主動層與無機層間更大的接觸面積，能在有機層內幫助收集電子，並藉由高載子遷移率的無機通道傳送至ITO電極。第三，此二氧化鈦奈米柱可以降低激子復合的機率，幫助激子分離。因此元件效率能有效的被改善至5.61%。在論文的最後，我們將工研院研發的低能隙材料(ITRI P47:PC70BM)應用在我們倒置結構太陽能電池上，藉由調整主動層厚度改善光吸收之外，同時配合使用NiO層介於主動層以及銀電極之間做為電子阻擋層，阻擋電子傳送到電極銀處與電洞復合，有效抑制漏電流。Organic photovoltaic devices are very attractive for their advantages of flexibility, light-weight, and large-area production at a dramatically low cost. In this study, the PV2000 material is used as a photoactive layer, which has a larger relative energy difference between the HOMO level of the electron-donating polymer and the LUMO level of the electron acceptor (energy difference ~1.7 eV) as compared to the standard P3HT:PCBM system, thereby leading to a larger VOC.
The better contact in the interface is achieved by the post-annealing process, which corrects the defects between electrode and polymer layer interface. Moreover, the thermally induced morphology modification, crystallization and improved interfacial transportation, thereby leading to better charge collection and reduced series resistance. These results show that the process of post-annealing is very important for our PV2000 inverted device.
We used solution process to replace deposition to spin NiO layer on active layer. NiO layer acts as an interfacial electron-blocking layer/hole-transporting layer (EBL/HTL). Utilizing its higher LUMO (lowest unoccupied molecular orbital) could block electron leakage to anode to recombine with hole. The leakage current is reduced to improve the power conversion efficiency of inverted structure devices.
When the TiO2 nanorods are introduced, an improvement of light harvest and photocurrent is achieved due to several factors. First, the photoactive layer is thickened and the light path is increased to have more light absorption. Second, the morphology is modified to provide the photoactive layer and inorganic layer a larger contact area for efficient charge collection. Third, the TiO2 nanorods enhance the photoluminescence quenching, indicating improved electron-hole dissociation. In this way, the high PCE of 5.61% from inverted PSCs is achieved.
In the second part of this work, our investigation apply the low band gap material (ITRI P47:PC70BM) as the photoactive layer. The light harvest is improved by adjusting the thickness of photoactive layer. In addition, we introduce the solution-process NiO layer between photoactive layer and silver as an electron blocking layer, therefore, the electron is forced to move toward the ITO electrodes, increasing the selectivity of the charge carriers and the shunt resistance of the photovoltaic cell
Performance Analysis of IEEE 802.11 Distributed Coordination Function With Frozen Time
No full textIEEE 802.11 無線網路在最近幾年中成為了最受歡迎的無線區域網路技術(WLAN)，其中媒體存取控制協定(MAC)跟分散式擷取協定(DCF)已被明確規範為媒體存取技術，且廣泛的應用在新穎網路技術上；因此有效且深入的了解IEEE802.11 分散式擷取協定(DCF)技術為本篇論文主要探討重點，現存許多研究已經討論過這項議題，但這些研究都忽略許多實際上協定的細部行為規範。
本篇論文將細部討論現存模型在討論分散式擷取協定(DCF)上的問題，並針對此些問題提出一個新穎的分析模型，此模型考慮實際擷取通道協定狀況，並細部考慮各端點間的行為模式。根據此分析模型，我們可以簡易，但有效率且正確的分析無線區域網路效能。分析結果包含有效傳送機率(Transmission Probability) 、各端點吞吐量(Throughput) 、整體吞吐量(Aggregate Throughput)、傳送延遲(Delay Time)、及有效傳送時間間距(Interarrival Time)。最後藉由Qaulnet 模擬軟體模擬分析無線網路環境，與現存分析模型比較可有效證明我們模型正確性。Recently, IEEE 802.11 protocol has been widely implemented in wireless local area networks (WLAN). The primary medium access control (MAC) technique, distributed coordination function (DCF), that specified contention-based medium access mechanism has been widely used to support applications in new regimes. Fully understanding IEEE 802.11 DCF is the focus of this article. This topic has already been discussed by several existing models, however most of them ignored some protocol details.
This thesis is about the problems of existing models with DCF protocol and provides a new model that takes behaviors of the channel and more details into consideration. Based on the proposed model,we perform simple, but rigorously accurate analysis model of saturation extensive performance in WLAN to present our results in the transmitted probability, throughput, and interarrival time. All the findings are verified by Qualnet Simulation to ensure the accuracy and thoroughness of the proposed model
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
