硒化锑薄膜太阳电池的模拟与结构优化研究

采用wx-AMPS模拟软件对硒化锑(Sb_2Se_3)薄膜太阳电池进行建模仿真,将CdS, ZnO和Sn02的模型应用到Sb_2Se_3太阳电池的电子传输层中.结果显示,应用CdS和ZnO都能实现较高的器件性能,并发现电子传输层电子亲和势(Xe-ETL)的变化能够调节Sb_2Se_3太阳电池内部的电场分布,是影响器件性能的关键参数之一.过高或者过低的Xe-ETL都会使电池的填充因子降低,导致电池性能劣化.当Xe-ETL为4.2eV时,厚度为0.6μm的Sb_2Se_3太阳电池取得了最优的7.87%的转换效率.应用优化好的器件模型,在不考虑Sb_2Se_3层缺陷态的理想情况下,厚度为3μm的Sb_2Se_3太阳电池的转换效率可以达到16.55%(短路电流密度J_(SC)=34.88 mA/cm~2、开路电压V_(OC)=0.59 V、填充因子FF=80.40%).以上模拟结果表明,Sb_2Se_3薄膜太阳电池在简单的器件结构下就能够获得优异的光电性能,具有较高的应用潜力.     

Ag-ZnO混合薄膜在聚合物太阳能电池中的应用

采用旋涂法研制了Ag浆SC100-ZnO混合薄膜,系统研究了不同混合比例SC100∶ZnO薄膜作为电子传输层或光散射层对聚合物太阳能电池器件性能的影响,并讨论了其中存在的物理机制。研究发现,采用少量SC100(1%和2.5%)混合的薄膜作为光散射层,可以提高器件的性能参数(短路电流密度和填充因子),器件的光电转换效率分别提高了4.4%和5%。     

双电子传输层结构硫硒化锑太阳电池的界面特性优化

硫硒化锑薄膜太阳电池因其制备方法简单、原材料丰富无毒、光电性质稳定等优点,成为了光伏领域的研究热点.经过近几年的发展,硫硒化锑太阳电池的光电转换效率已经突破10%,极具发展潜力.本文针对硫硒化锑太阳电池中n/i界面引起的载流子复合进行了深入研究.发现硫硒化锑太阳电池的界面特性会受到界面电子迁移能力和能带结构两方面的影响.界面电子迁移率的提高能使电子更有效地传输至电子传输层,实现器件短路电流密度和填充因子的有效提升.在此基础上,引入ZnO/Zn_1-xMg_xO双电子传输层结构能够进一步优化硫硒化锑太阳电池性能.其中,Zn_1-xMg_xO能级位置的改变可以同时调节界面和吸光层的能级分布,在Zn_1-xMg_xO导带能级为-4.2 eV,对应Mg含量为20%时,抑制载流子复合的效果最为明显,硫硒化锑太阳电池也获得了最佳的器件性能.在去除缺陷态的理想情况下,双电子传输层结构硫硒化锑太阳电池在600 nm厚时获得了20.77%的理论光电转换效率,该研究结果为硫硒化锑太阳电池...     

在空穴传输层聚(3-己基噻吩)中添加1,8-二碘辛烷改善碳基钙钛矿太阳能电池的性能

无空穴传输层的碳基钙钛矿太阳能(PSCs)电池拥有成本低、制备步骤简单、稳定性高的优点,应用前景广阔.但是碳电极与活性层的直接接触,导致器件的光电转换效率普遍低于其他金属电极的钙钛矿太阳能电池.本文使用聚(3-己基噻吩)(P3HT)作为器件的空穴传输层,相比传统的有机空穴传输层材料Spiro-OMeTAD,具有低成本和易于制造的优点,并通过在P3HT中掺杂1,8-二碘辛烷(DIO)的方法优化其光电性能,提升了载流子的迁移率,阻挡电子的运输,降低界面复合,改善了碳电极与器件的界面接触,提高了短路电流J_(sc)和填充因子FF,使器件的初始光电转换效率从14.06%提升至15.11%.器件在氮气环境下测试稳定性,连续光照1000 h后器件的转换效率仍保持在98%以上.     

4，4＇，4＂-三（N-3-甲基苯基-N-苯基氨基）三苯胺掺杂MoOx作为空穴传输层对有机太阳电池性能的影响永

通过采用4,4’,4”．三（N-3-甲基苯基-N-苯基氨基）三苯胺（m-MTDATA）掺入MoO。作为器件的空穴传输层来提高酞菁铜（CuPc）／C60小分子有机太阳电池的效率．采用真空蒸镀的方法制备了一系列器件,其中结构为铟锡氧化物（ITO）／m-MTDATA：MoO2（3：1）（30nm）／CuPc（20nm）／C60（40nm）／4,7-二苯基-1,10-菲罗啉（Bphen）（8nm）／LiF（0．8nm）／Al（100am）的器件,在AMl．5（100mW／cm2）模拟太阳光的照射条件下,开路电压Koc=0．40V,短路电流Jsc=6．59mA／cm2填充因子为0．55,光电转换效率达1．46％,比没有空穴传输层的器件ITO／CuPc（20nm）／C60（40nm）／Bphen（8nm）／LiF（0．8nm）／A1（100nm）光电转换效率提高了38％．研究表明,加入m-MTDATA：MoO2（3：1）（30am）空穴传输层减小了有机层和ITO电极之间的接触电阻,从而减小了整个器件的串联电阻,提高了器件的光电转换效率．     

溶剂预处理结合热退火提升聚噻吩结晶度及其光伏性能

活性层的微观形貌在很大程度上决定了聚合物光伏器件的性能表现并依赖于制备工艺条件。为了改善薄膜内部分子排布结构并追求较高的器件光电转化效率,采用溶液法制备了基于P3HT：PCBM的聚合物太阳能电池（器件结构:ITO/PEDOT：PSS/P3HT：PCBM/Al）,通过改变器件制备流程中活性层退火处理工艺,研究了热退火、溶剂退火以及溶剂预处理结合热处理的双重退火对聚合物太阳电池性能的影响。研究发现:双重退火的光伏器件的各项性能参数均优于单一退火处理器件,获得了3.25%的光电转化效率。原子力显微镜及X射线衍射仪的表征结果进一步证明:双重退火处理能够在促进聚合物给体良好有序结晶的同时保证共混组分适度地相分离,从而有利于光生激子的解离以及载流子的传输。     

溶剂预处理结合热退火提升聚噻吩结晶度及其光伏性能

活性层的微观形貌在很大程度上决定了聚合物光伏器件的性能表现并依赖于制备工艺条件。为了改善薄膜内部分子排布结构并追求较高的器件光电转化效率,采用溶液法制备了基于P3HT∶PCBM的聚合物太阳能电池(器件结构:ITO/PEDOT∶PSS/P3HT∶PCBM/Al),通过改变器件制备流程中活性层退火处理工艺,研究了热退火、溶剂退火以及溶剂预处理结合热处理的双重退火对聚合物太阳电池性能的影响。研究发现:双重退火的光伏器件的各项性能参数均优于单一退火处理器件,获得了3.25%的光电转化效率。原子力显微镜及X射线衍射仪的表征结果进一步证明:双重退火处理能够在促进聚合物给体良好有序结晶的同时保证共混组分适度地相分离,从而有利于光生激子的解离以及载流子的传输。     

Cs_2CO_3共蒸阴极对有机电致发光器件性能的影响(英文)

研究了碳酸铯(Cs2CO3)掺杂8-羟基喹啉铝(Alq3)作为电子注入层对有机电致发光器件性能的影响。结果表明,与常用的Cs2CO3超薄层作电子注入层相比,Cs2CO3∶Alq3共蒸阴极对器件效率和亮度有很大提高,器件电流效率从3.1 cd/A(Cs2CO31 nm/Al)提高到6.5 cd/A(Cs2CO33%∶Alq3/Al)。器件性能的提高归因于Cs2CO3∶Alq3共蒸阴极比单层Cs2CO3阴极具有更好的电子注入能力和电子传输性能。薄膜形貌表明,共蒸阴极能有效降低Alq3表面粗糙度,有助于提高器件发光性能及寿命。     

MEH-PPV与TiO2共混体系太阳电池性能分析

以MEH-PPV(poly(2-methoxy-5-(2'-ethylhexoxy)-1,4-phenylene vinylene)为电子给体材料(Donor,D),TiO2纳米线为电子受体材料(Aceeptor,A),制成了共混体系太阳电池.从D/A材料共混体系的紫外可见吸收光谱(UV-vis)、光荧光谱(PL)、器件的电荷传输的光导J-V图等方面,分析了MEH-PPV:TiO2体系器件性能变化的原因.得出了当在纯MEH-PPV中掺入TiO2纳米线时,共混体系的太阳电池性能大幅度增加,当D/A比例为1:3时,其太阳电池在AM1.5光照下,其开路电压Voc为0.7 V,短路电流密度Jsc为0.3 mA/cm2填充因子FF为30.5%,能量转换效率n为0.091%.其能量转换效率比纯MEH-PPV作为活性层器件提高近60倍.发现当共混体系用苯硫酚溶剂回流时,其器件性能又提高了近一倍.     

P-I-N型锡铅钙钛矿太阳电池性能的限制因素及解决策略

锡铅钙钛矿太阳电池已被证明可以用于全钙钛矿叠层太阳电池中,作为窄带隙底电池进一步提高器件光电转换效率.目前, P-I-N型锡铅钙钛矿太阳电池的最高效率为21.7%,明显低于铅基钙钛矿太阳电池.本文分析了限制其性能提高的主要因素,并针对性地总结了近几年研究工作者们提出的有效解决策略,主要包括:1)通过添加富锡化合物、强还原剂或含大的有机阳离子的化合物以抑制Sn~(2+)氧化,减少锡铅钙钛矿材料p型掺杂程度,降低电池开路电压损耗; 2)通过调控组分、改变钙钛矿薄膜制备方法、溶剂工程或添加含功能性基团的化合物以延缓锡铅钙钛矿薄膜结晶生长速率,提高薄膜质量; 3)通过选用合适的电子传输层或空穴传输层,减少能级失配对载流子传输的影响或避免载流子传输层的本身不稳定性对器件的影响.最后,本文展望了锡铅钙钛矿太阳电池的未来发展,认为其不仅有望实现高效稳定的单结太阳电池,而且还可以应用于高效全钙钛矿叠层太阳电池.     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

Real-time, continuous-wave terahertz imaging by a pyroelectric camera

Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.