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71.
Fullerene thin films have been deposited by thermal evaporation on glass substrates at room temperature. A comprehensive optical characterization was performed, including low-level optical absorption measured by photothermal deflection spectroscopy. The optical absorption spectrum reveals a direct bandgap of 2.3 eV and absorption bands at 2.8 and 3.6 eV, which are related to the creation of charge-transfer excitons. Various photodiodes on indium-tin-oxide coated glass substrates were also fabricated, using different metallic contacts in order to compare their respective electrical characteristics. The influence of a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) buffer layer between the indium-tin-oxide electrode and the fullerene semiconductor is also demonstrated. These results are discussed in terms of the workfunction for each electrode. Finally, the behaviour of the external quantum efficiency is analyzed for the whole wavelength spectrum. 相似文献
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73.
FM光端机的光器件选择及其应用电路设计 总被引:1,自引:0,他引:1
主要介绍了FM光端机中光发射机及接收机所用的光源和光检测器的工作原理,阐述了光源和光检测器等光器件的选择原则,提出了光源驱动电路和光接收及放大电路的设计方法. 相似文献
74.
A series of 2′,7′‐diarylspiro(cyclopropane‐1,9′‐fluorene) derivatives are efficiently synthesized and characterized to determine the reason for the “green‐light” emission of these compounds. These compounds exhibit bright‐violet to blue photoluminescence (PL) (λPLmax = 353–419 nm) with excellent PL quantum efficiencies (ΦPL = 83–100 %) in solution and show high thermal stabilities (Td = 267–474 °C). The variation of the optical properties of these molecules in the solid state depends on the different stacking modes of these compounds containing different substituents, which are revealed by crystallographic analysis. CH…π hydrogen bonds instead of intermolecular π–π interactions act as the driving force between adjacent fluorenes, even though a very small dialkyl group (cyclopropane) is introduced at the C‐9 position of fluorene. The crosslike molecular stacking efficiently reduces the energy transfer between the herring‐like aggregates and therefore results in the absence of a “green‐light” emission tail. In order to determine the cause of the “green‐light” emission tails, the fluorescence spectra of the films annealed in N2 or in air are recorded. Broad green‐light emission tails were observed for the films annealed in air, which might be caused by fluorenone defects generated during processing or during the course of the photophysical analysis by reaction with residual oxygen. 相似文献
75.
针对Vertical Bell Laboratories Layered Space-Time(V-BLAST)系统中干扰抵消-最小均方误差滤波(Interference Cancellation-Mimmum Mean Square Error filtering:IC-MMSE)迭代检测算法,本文对使用实际估计CSI(Channel State Information)的IC—MMSE迭代检测算法进行了研究.通过在MMSE滤波中考虑信道估计误差,提出了修正的MMSE滤波.与忽略信道估计误差的MMSE滤波相比,修正的MMSE滤波能够获得较小的均方误差.仿真结果表明采用修正的MMSE滤波能够获得显著的性能增益,同时不会增加计算复杂度。 相似文献
76.
液晶空间光调制器是实时光学信息处理中的重要器件,本文分析了液晶空间光调制器的光学调制特性及其目前在全息领域的主要应用.并根据液晶空间光调制器实时再现计算全息图的原理,提出利用计算全息技术得到单元合成全息图阵列,通过计算机控制向液晶空间光调制器输出合成全息图序列进行实时光电再现进而实现合成全息动感的方法,分析了基本原理和实现方法并给出了相应实验结果. 相似文献
77.
火/气探测系统(FGS)是保护人员、环境及设备关键的安全部件,但火/气探测系统的产品、技术和设计基础与仪控系统不完全相同,因此国际上一直质疑是否应将FGS纳入安全仪表系统(SIS)及要求具有SIL2或SIL3安全完整性等级认证。本文综合TüV及ISA专家的视点从不同视角探讨如何妥善使用安全标准及技术并优化火/气探测设备布置以期获得最大的风险减轻效果。 相似文献
78.
Daniel Lersch Gheorghe Pascovici Benedikt Birkenbach Bart Bruyneel Jürgen Eberth Herbert Hess Peter Reiter Andreas Wiens Heinz Georg Thomas for the AGATA Collaboration 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,640(1):223
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80.
P.A.C. Quist T.J. Savenije M.M. Koetse S.C. Veenstra J.M. Kroon L.D.A. Siebbeles 《Advanced functional materials》2005,15(3):469-474
The effect of annealing blends of poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐1,4‐phenylenevinylene) (MDMO‐PPV) and a poly(cyanoether phenylenevinylene) (PCNEPV) on the photoconductivity is studied. Charge carriers are generated by pulsed‐laser excitation and their mobility and decay kinetics are monitored using time‐resolved microwave conductivity (TRMC) measurements. Photoexcitation leads to the formation of an exciton, which can undergo charge separation at an interface between the electron‐donating MDMO‐PPV and the electron‐accepting PCNEPV. The electrons and holes formed in this way must escape from each other to contribute to the photoconductivity. The photoconductivity of the blends is found to increase by almost two orders of magnitude upon thermal annealing for three hours at 100 °C. This increase is attributed to the occurrence of phase separation in the polymer/polymer film, resulting in PCNEPV‐rich parts. The formation of PCNEPV‐rich parts allows the electron to diffuse away from the interface, which favors escape from geminate recombination, leading to a higher photoconductivity. 相似文献