银纳米颗粒对聚合物太阳能电池性能的提高

采用水溶性银纳米颗粒附着在反型太阳能电池的电子传输层上,用以提高有机太阳能电池的短路电流。所制备的器件结构为ITO/ZnO/Ag NPs/P3HT(Poly 3-hexylthiophene):PC_[60]BM/MoO₃/Ag。其金属银纳米颗粒的表面等离激元在410 nm处出现了共振吸收峰,半峰全宽约为60 nm。器件的光电流在可见光范围内均有所增加,短路电流相对于标准器件提高了20.2%,光电转化效率相对提高了17.2%。     

金纳米四面体增强有机太阳电池光吸收及光伏性能研究

为增强有机太阳能电池的光利用率,提高能量转换效率,本文合成了金四面体形状的纳米粒子,并用聚苯乙烯磺酸钠(PSS)包裹形成了核壳结构的金纳米四面体(Au@PSS tetrahedra NPs).将其掺杂到有机太阳能电池空穴提取层与活性层的界面处,利用表面等离子体共振效应来增强活性层对光的吸收,从而提高有机太阳能电池的能量转换效率.研究了掺杂浓度和PSS包裹厚度对电池性能的影响.结果表明:掺杂浓度为6%时,器件性能最佳,能量转换效率达到3.08%; PSS壳层厚度优化为2.5 nm时,转换效率达到3.65%,较标准电池提升了22.9%.电池性能的改善主要源于金四面体纳米粒子的共振吸收峰位于给体材料吸收谱范围内,纳米粒子的共振促进了给体的吸收,同时PSS壳层的引入促进了激子的解离和电荷的转移,上述因素的改善提升了电池的短路电流、填充因子和转换效率.     

利用叠层一维光子晶体调控半透明有机太阳能电池的性能

利用叠层一维光子晶体提高半透明有机太阳能电池的光电转换效率和调控器件的透视颜色.采用传输矩阵法计算了基于叠层一维光子晶体的半透明有机太阳能电池中活性层的吸收光谱和器件的透过率光谱,进而计算了器件的光电转换效率和透视颜色.研究结果表明,通过合理设计叠层一维光子晶体中顶光子晶体和底光子晶体的禁带中心波长,可以将器件的光电转换效率提高24.4%.此外,通过控制顶光子晶体和底光子晶体的禁带中心波长,可以调控半透明有机太阳能电池的透视颜色,获得透视颜色分别为蓝色、绿色和红色的半透明电池器件.与单层一维光子晶体相比,叠层一维光子晶体可以使器件获得更高的光电转换效率,并能在更大光谱范围内调控器件的透视颜色.     

基于金纳米棒@二氧化硅表面等离子体共振增强的有机太阳能电池

把包裹SiO₂的金纳米棒（Au NRs@SiO₂）掺杂到有机太阳能电池的活性层中,利用表面等离子体共振效应来增强活性层对光的吸收,从而提高有机太阳能电池的能量转换效率。研究了不同掺杂浓度和不同包裹厚度对电池性能的影响。结果表明,掺杂浓度为1.5%时,器件性能最佳,能量转换效率达到4.02%;SiO₂壳层厚度为3 nm时,转换效率达到4.38%,较标准电池提升了29.2%。     

MEH-PPV/CdSe纳米复合器件的光电导特性的研究

以CdO和Se粉作为前驱物,在TOPO/TOP有机体系中制备了CdSe纳米晶,将其与聚合物MEH-PPV复合制备了复合光电导器件,研究了它的光电导特性,并将其与单层MEH-PPV光电导器件的特性进行了比较。结果发现纳米复合光电导器件的光电流响应光谱的2个峰的位置基本上与MEH-PPV和CdSe纳米晶的吸收峰的位置相对应,这说明CdSe纳米晶和聚合物MEH-PPV的吸收对光电流都有贡献,主要是由于CdSe纳米晶和MEH-PPV界面处的激子离化和电荷转移造成的。而且复合器件的光电流较单层有所增强,且MEH-PPV器件光谱的响应范围更宽。     

基于三元非富勒烯体系的高效有机太阳能电池

有机材料的"窄吸收"特性制约了有机太阳能电池(OPVs)性能的进一步突破,二元体异质结薄膜难以实现对太阳能的有效宽光谱利用.三元OPVs在二元体系中引入吸收互补的第三组分,能够增强器件光吸收,实现光电转化效率的大幅提升.近年来,非富勒烯受体材料的飞速进展,多次刷新有机太阳能电池最高效率记录,丰富并扩展了三元受体材料的选择范围.本文以非富勒烯受体材料Y6作为第三组分材料,高效率非富勒烯太阳能电池PBDB-T-2F:IT-4F作为基础二元器件,研究并分析了以双非富勒烯材料为受体的三元有机太阳能电池工作机理.通过光电特性分析,发现Y6的引入不仅能够增强器件近红外区域的光吸收能力,而且能够有效抑制双分子复合,提高电荷取出率,从而提高器件能量转换效率.通过调节Y6在三元体系中的质量百分比,在Y6占比为20 wt%时,器件实现最高的能量转换效率12.48%,相比于基础二元器件(10.59%)实现了17.85%的性能提升.     

一种新的基于频域有限差分方法的小周期有机太阳能电池的光电特性

由MoO₃/Ag/MoO₃ （MAM）组成的多层膜结构非常有希望替代ITO作为有机太阳能电池中的透明阳极.然而,基于MAM结构的有机太阳能电池光吸收能力较弱.为此,引入了一种小周期短节距金属光栅,利用表面等离子激元增强活性层的光吸收.借助于频域有限差分方法求解麦克斯韦方程和半导体方程,探讨了有机太阳能电池结构的光学和电学性质.分析结果表明：与平面结构相比,活性层中的光吸收大大提高;同时,当凹槽宽度为4 nm,能量转换效率提高了49%.相关结果有助于更好地开发和利用无ITO层的有机太阳能电池.     

有机无机杂化固态太阳能电池的研究进展

近年来, 由于钙钛矿材料优良的光学吸收和电荷传导特性, 有机无机杂化固态太阳能电池取得了突破性的进展. 自2009年首次报道了光电转换效率为3.8%的钙钛矿太阳能电池以来, 该类电池的效率不断突破. 基于介孔薄膜的电池已取得了超过16.7%的认证光电转换效率, 基于平板异质结结构电池光电转换效率达到19.3%, 已接近传统硅基太阳能电池的光电转换效率. 本文将介绍有机无机杂化钙钛矿作为光电材料的光学物理结构特性, 以及在固态太阳能电池中的应用. 基于固态钙钛矿太阳能电池结构上的差异, 分别介绍其在多孔结构、平板异质结结构、柔性结构以及无空穴传导材料结构电池工作特性和各自优势, 以及影响电池特性的主要影响因素, 特别是钙钛矿成膜控制等. 并阐述对钙钛矿电池的理解和进一步提高固态钙钛矿电池光电转换效率需要关注的重点以及展望.     

基于Al_2O_3/MoO_3复合阳极缓冲层的倒置聚合物太阳能电池的研究

采用旋涂Al_2O_3前驱体溶液和低温退火的方法在活性层上形成Al_2O_3薄膜,并与MoO_3结合形成Al_2O_3/MoO_3复合阳极缓冲层,制备了以聚3-己基噻吩:[6.6]-苯基-C_(61)-丁酸甲酯(P3HT:PC_(61)BM)为活性层的倒置聚合物太阳能电池,并通过改变Al_2O_3前驱体溶液的浓度来分析复合阳极缓冲层对器件性能的影响.结果发现,Al_2O_3/MoO_3复合阳极缓冲层能有效调控倒置聚合物太阳能电池的光电性能及其稳定性.当Al_2O_3前驱体溶液的浓度为0.15%时,器件光伏性能达到最优值,与MoO_3单缓冲层的器件相比,光电转换效率(PCE)由3.85%提高到4.64%;经过80天老化测试后,具有复合阳极缓冲层的器件PCE保留为初始值的76%,而单缓冲层的器件PCE已经下降到50%以下.器件性能得到改善的原因是Al_2O_3/MoO_3复合阳极缓冲层增强了倒置太阳能电池器件阳极对空穴的收集能力,同时钝化了器件活性层,从而提升了太阳能电池器件的光伏性能及其稳定性.     

利用银纳米立方增强效率的多层溶液加工白光有机发光二极管

金属纳米粒子的局域表面等离子体共振效应常被用于增强有机发光二极管中激子辐射强度,其增强效果与金属纳米粒子的共振波长、共振强度及其与激子之间的耦合密切相关.本文将具有较强局域表面等离子体共振效应的银纳米立方引入多层溶液加工白光有机发光二极管中提升器件性能.在传统的溶液加工有机发光二极管中,发光层主体一般具有较强的空穴传输性,因此激子主要在发光层/电子传输层界面附近复合.本文将银纳米立方掺入电子传输层中,使银纳米立方与激子之间产生充分的耦合作用,提高激子发光强度.对银纳米立方包裹二氧化硅外壳,一方面优化纳米立方与激子之间的距离,另一方面减小其对器件中电荷传输的影响.通过优化银纳米立方的浓度,多层溶液加工白光有机发光二极管的电流效率达到30.0 cd/A,是基础器件效率的2倍.另外,由于银纳米立方的等离子体共振光谱较宽,同时增强了白光中蓝光和黄光的强度,因此引入银纳米立方基本没有影响白光的色度.研究结果表明引入金属纳米粒子是提升多层溶液加工发光二极管性能的有效方法.     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.