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排序方式: 共有543条查询结果,搜索用时 15 毫秒
61.
62.
Effects of a perfluorinated compound as an additive on the power conversion efficiencies of polymer solar cells 总被引:1,自引:0,他引:1
Seonju JeongSung-Ho Woo Hong-Kun LyuYoon Soo Han 《Solar Energy Materials & Solar Cells》2011,95(7):1908-1914
A perfluorinated compound, 4-amino-2-(trifluoromethyl)benzonitrile (ATMB), was applied as an additive to polymer solar cells (PSCs) with P3HT [poly(3-hexylthiophene)]:PCBM [[6,6]-phenyl-C61-butyric acid methyl ester] blend films. The addition of 6 wt% ATMB to a P3HT:PCBM layer led to an increased power conversion efficiency of 5.03% due to the enhanced short circuit current and fill factor when compared with that of the reference cell without an additive. On the other hand, the devices with 4-aminobenzonitrile as an additive, not containing fluorine atoms in the molecule, displayed lower PCEs than that of the reference cell. The UV-visible absorption spectra, X-ray measurements and carrier mobility studies revealed that ATMB facilitated ordering of the P3HT chains, resulting in higher absorbance, larger crystal size of P3HT and enhanced hole mobility. XPS depth profiling measurements also showed that the additive molecules were predominantly positioned in the range of 25 nm under the surface of the P3HT:PCBM film, leading to improved fill factor. 相似文献
63.
旋转机械振动信号基于EMD的HT和STFT时频分析比较 总被引:2,自引:0,他引:2
基于经验模态分解(Empinrical Mode Decomposition,EMD)的希尔伯特变换(Hilbert Transformation,HT),是先把一列时间序列数据通过经验模态分解,然后经过希尔伯特变换获得频谱的信号处理新方法。介绍了该方法的理论和算法。对仿真和旋转机械油膜涡动故障振动信号分别用基于EMD和基于STFT(Short-Time Fourier Transformation,STFT)的时频分析进行了比较研究,研究结果说明,用基于EMD的HT方法对旋转机械的振动信号进行时频分析比STFT有效。 相似文献
64.
《International Journal of Hydrogen Energy》2020,45(58):33111-33127
A numerical method was developed for optimising solar–hydrogen energy system to supply renewable energy for typical household connected with the grid. The considered case study involved household located in Diyala Governorate, Iraq. The solar–hydrogen energy system was designed to meet the desired electrical load and increase the renewable energy fraction using optimum fuel cell capacity. The simulation process was conducted by MATLAB based on the experimental data for electrical load, solar radiation and ambient temperature at a 1-min time-step resolution. Results demonstrated that the optimum fuel cell capacity was approximately 2.25 kW at 1.8 kW photovoltaic power system based on the average of the daily energy consumption of 6.8 kWh. The yearly renewable energy fraction increased from 31.82% to 95.82% due to the integration of the photovoltaic system with a 2.25 kW fuel cell used as a robust energy storage unit. In addition, the energy supply, which is the economic aspect for the optimum system, levelised electricity cost by approximately $0.195/kWh. The obtained results showed that the proposed numerical analysis methodology offers a distinctive property that can be used effectively to optimise hybrid renewable energy systems. 相似文献
65.
Jong Bok Kim Ze-Lei Guan Stephanie Lee Eleni Pavlopoulou Michael F. Toney Antoine Kahn Yueh-Lin Loo 《Organic Electronics》2011,12(11):1963-1972
Contrary to polymer solar cells with bulk-heterojunction active layers, devices with planar-heterojunction active layers allow the decoupling of active layer phase separation from constituent crystallization, and their relative influence on device performance. We fabricated planar-heterojunction devices by first processing the electron donor and electron acceptor in isolation; they were subsequently laminated across the donor–acceptor interface to establish electrical contact. Thermal annealing was intentionally avoided after lamination to maintain the pristine charge transfer interface. Lamination thus obviates the need for solvent orthogonality; more importantly, it provides independent process tuning of individual organic semiconductor layers, ultimately allowing control over constituent structural development. We found the short-circuit current density of planar-heterojunction solar cells comprising poly(3-hexyl thiophene), P3HT, and [6,6]-phenyl-C61-butyric acid methyl ester, PCBM, as the electron donor and acceptor, respectively, to be generally independent of the annealing history of P3HT. On the contrary, thermal annealing PCBM prior to lamination mainly led to a reduction in short-circuit current density. This deterioration is correlated with the development of preferentially oriented PCBM crystals that hinders electron transport in the vertical direction. 相似文献
66.
Claudio Girotto Davide Moia Barry P. Rand Paul Heremans 《Advanced functional materials》2011,21(1):2-2
In this study, we report high performance organic solar cells with spray coated hole‐transport and active layers. With optimized ink formulations we are able to deposit films with controlled thickness and very low surface roughness (<10 nm). Specifically we deposit smooth and uniform 40 nm thick films of poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as well as films composed of a mixture of poly(3‐hexyl thiophene) (P3HT) and the C60‐derivative (6,6)‐phenyl C61‐butyric acid methyl ester (PCBM) with thicknesses in the range 200–250 nm. To control film morphology, formation and thickness, the optimized inks incorporate two solvent systems in order to take advantage of surface tension gradients to create Marangoni flows that enhance the coverage of the substrate and reduce the roughness of the film. Notably, we achieve fill factors above 70% and attribute the improvement to an enhanced P3HT crystallization, which upon optimized post‐drying thermal annealing results in a favorable morphology. As a result, we could extend the thickness of the layer to several hundreds of nanometers without noticing a substantial decrease of the transport properties of the layer. By proper understanding of the spreading and drying dynamics of the inks we achieve spray coated devices with power conversion efficiency of 3.75%, with fill factor, short circuit current and open circuit voltage of 70%, 9.8 mA cm?2 and 550 mV, respectively. 相似文献
67.
Anthony J. Morfa Alexandre M. Nardes Sean E. Shaheen Nikos Kopidakis Jao van de Lagemaat 《Advanced functional materials》2011,21(13):2580-2586
The charge‐collection dynamics in poly(3‐hexylthiophene:[6,6]‐phenyl‐C61‐butyric acid methyl ester (P3HT:PCBM) bulk heterojunctions are studied in thick (>1 μm) devices using time‐of‐flight measurements and external quantum‐efficiency measurements. The devices show Schottky‐diode behavior with a large field‐free region in the device. Consequently, electron transport occurs by diffusion in the bulk of the active layer. At high applied biases where the depletion region spans the entire active layer, normal time‐of‐flight transients are observed from which the electron mobility can be determined. Here, the electron mobility follows Poole–Frenkel behavior as a function of field. At lower applied biases, where the depletion region only spans a small portion of the active layer, due to a high density of dark holes, the recombination kinetics follow a first‐order rate law with a rate constant about two orders of magnitude lower than that predicted by Langevin recombination. 相似文献
68.
[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) / poly (3-hexylthiophene) (P3HT) heterojunction has not only the absorption in ultraviolet light for PCBM,but also the absorption in visible light for P3HT, which widens the incident light harvest range, improving the photoelectrical response of hybrid solar cell effectively.Using conducting polymers blend heterojunetion consisting of C60 derivatives PCBM and P3HT as charge carrier transferring medium to replace I3-/I- redox electrolyte and dye, a novel flexible solar cell was fabricated in this study.The influence of PCBM/P3HT mass ratio on the photovoltaic performance of the solar cell was also studied.flexible solar cell achieved a light-to-electric energy conversion efficiency of 1.04%, an open circuit voltage fill factor (FF) of 0.46. 相似文献
69.
设计了一种直流电能充电器,该充电器可将直流电源的能量传递到3.6 V以上的可充电电池中。系统根据输入电压不同采用MC34063和HT7750来构建供电电路给电池充电,经过89C51单片机控制AD0832来检测电源输出电压的大小,从而判断是否对电池进行充电,并且检测时间的长短可以根据用户的需要进行设定,并通过数码管显示出来。为了提高单片机的工作效率,对单片机处于休眠和工作两种状态进行断续的检测。 相似文献
70.
《Organic Electronics》2014,15(9):2059-2067
Polymer solar cells (PSCs) are of great interest in the past decade owing to their potentially low-cost in the manufacturing by the solution-based roll to roll method. In this paper, a novel inverted device structure was introduced by inserting a high conductive PEDOT:PSS (hcPEDOT:PSS) layer between the Au nanoparticles (NPs)-embedded hole transport layer (PEDOT:PSS) and the top electrode layer. Power conversion efficiency (PCE) initially reached up to 4.51%, illustrating ∼10% higher compared with the device similarly enhanced by Au NPs plasmonics where only one PEDOT:PSS layer with the embedded Au NPs was used in single bulk heterojunction inverted PSCs based on the poly(3-hexylthiophene):[6,6]-phenyl C61-butyric acid methylester (P3HT:PCBM). The PCE was further improved from 4.51% to 5.01% by adding the high-boiling point solvent of 1,8-diiodooctane (DD) into the active layer, presenting ∼20% enhancement in PCE through dual effects of introducing the high boiling point solvent and the high conductive PEDOT:PSS layer. Morphologies of the active layers were characterised by SEM and AFM separately in the paper. 相似文献