Influence of Defect Density, Band Gap Discontinuity and Electron Mobility on the Performance of Perovskite Solar Cells

In this manuscript, we used the SCAPS-1D software to perform numerical simulations on a perovskite solar cell. These simulations were used to study the influence of certain parameters on the electrical behavior of the cell. We have shown in this study that electron mobility is strongly influenced by the thickness of the absorber, since electron velocity is reduced by thickness. The influence of the defect density shows that above 1016 cm-3 all the electrical parameters are affected by the defects. The band discontinuity at the interface generally plays a crucial role in the charge transport phenomenon. The importance of this study is to enable the development of good quality perovskite solar cells, while taking into account the parameters that limit solar cell performance.

Excitation of defect modes from the extended photonic band-gap structures of 1D photonic lattices

This paper stuides numerically the model equation in a one dimensional defective photonic lattice by modifying the potential function to a periodic function. It is found that defect modes （DMs） can be regarded as Bloch modes which are excited from the extended photonie band-gap structure at Bloch wave-numbers with kx = 0. The DMs for both positive and negative defects are considered in this method.

Surface defect gap solitons in two-dimensional optical lattices

We investigate the existence and stability of surface defect gap solitons at an interface between a defect in a two-dimensional optical lattice and a uniform saturable Kerr nonlinear medium. The surface defect embedded in the two-dimensional optical lattice gives rise to some unique properties. It is interestingly found that for the negative defect, stable surface defect gap solitons can exist both in the semi-infinite gap and in the first gap. The deeper the negative defect, the narrower the stable region in the semi-infinite gap will be. For a positive defect, the surface defect gap solitons exist only in the semi-infinite gap and the stable region localizes in a low power region.

Surface defect gap solitons in one-dimensional dual-frequency lattices

We study the surface defect gap solitons in an interface between a defect of one-dimensional dual-frequency lattices and the uniform media. Some unique properties are revealed that such lattices can broaden the region of semi-finite gap, and the semi-finite gap exists not only in the positive and zero defects but also in the negative defect; unlike in the regular lattices, the semi-finite gap exists in the positive and zero defects but does not exist in the negative defect. In particular, stable solitons exist almost in the whole semi-finite gap for the positive and zero defects. These properties are different from other lattices with defects. In addition, it is found that the existence of surface dual-frequency lattice solitons does not need a threshold power.

Dynamic Control of Defective Gap Mode Through Defect Location

A one dimensional model is developed for defective gap mode（DGM）with two types of boundary conditions：conducting mesh and conducting sleeve.For a periodically modulated system without defect,the normalized width of spectral gaps equals to the modulation factor,which is consistent with previous studies.For a periodic system with local defects introduced by the boundary conditions,it shows that the conducting-mesh-induced DGM is always well confined by spectral gaps while the conducting-sleeve-induced DGM is not.The defect location can be a useful tool to dynamically control the frequency and spatial periodicity of DGM inside spectral gaps.This controllability can be potentially applied to the interaction between gap eigenmodes and energetic particles in fusion plasmas,and optical microcavities and waveguides in photonic crystals.

Repair of peripheral nerve defects by nerve transposition using small gap bio-sleeve suture with different inner diameters at both ends

During peripheral nerve transposition repair, if the diameter difference between transposed nerves is large or multiple distal nerves must be repaired at the same time, traditional epineurial neurorrhaphy has the problem of high tension at the suture site, which may even lead to the failure of nerve suture. We investigated whether a small gap bio-sleeve suture with different inner diameters at both ends can be used to repair a 2-mm tibial nerve defect by proximal transposition of the common peroneal nerve in rats and compared the results with the repair seen after epineurial neurorrhaphy. Three months after surgery, neurological function, nerve regeneration, and recovery of nerve innervation muscle were assessed using the tibial nerve function index, neuroelectrophysiological testing, muscle biomechanics and wet weight measurement, osmic acid staining, and hematoxylin-eosin staining. There was no obvious inflammatory reaction and neuroma formation in the tibial nerve after repair by the small gap bio-sleeve suture with different inner diameters at both ends. The conduction velocity, muscle strength, wet muscle weight, cross-sectional area of muscle fibers, and the number of new myelinated nerve fibers in the biosleeve suture group were similar to those in the epineurial neurorrhaphy group. Our findings indicate that small gap bio-sleeve suture with different inner diameters at both ends can achieve surgical suture between nerves of different diameters and promote regeneration and functional recovery of injured peripheral nerves.

Influence of defect states on band gaps in the two-dimensional phononic crystal of 4340 steel in an epoxy

The band structures of a new two-dimensional triangle-shaped array geometry of 4340 steel cylinders of square cross section in an epoxy resin were studied by the plane-wave expansion and supercell calculation method. The band gaps of this type of phononic crystals with different defects were calculated such as defect-free, 60° crystal linear defect states, 120° crystal linear defect states, and 180° crystal linear defect states. It was found that the band gap will emerge in different linear defects of the phononic crystals and the bandwidth of linear defect states is larger than that of the free-defect crystal by about 2.14 times within the filling fraction F = 0.1-0.85. In addition, the influence of the filling fraction on the relative width of the minimum band gap is discussed.

纳米GaP材料Ga填隙缺陷的EPR实验观察

利用电子顺磁共振 (EPR)技术对纳米GaP粉体材料的本征点缺陷进行了研究 ,结果表明 :由EPR信息的 g因子值 ( 2 .0 0 2 7± 0 .0 0 0 4 )可以确定纳米GaP粉体材料存在Ga自填隙(Gai)本征缺陷 ;纳米GaP粉体EPR信号超精细结构消失 ,以及谱线线宽 (ΔHPP)变窄等实验现象 ,可能是由纳米材料界面的无序性 ,以及缺陷原子和界面原子之间的电子交换造成的 ;在较低的测试温度范围内 ,升高温度引起纳米GaP材料发生晶界结构弛豫 ;当测试温度由1 0 0K升高至 42 3K时 。

添加剂提高宽带隙钙钛矿太阳电池的性能

该文研究聚对苯乙烯磺酸钠(PSS)对宽带隙钙钛矿薄膜及电池的影响。研究发现PSS添加剂可改善宽带隙钙钛矿薄膜的形貌,提升结晶度并减少缺陷态密度,这有利于抑制混合卤素宽带隙钙钛矿薄膜的相分离问题。J-V测试结果表明钝化后的宽带隙钙钛矿太阳电池性能得到明显提升。在掺有PSS的宽带隙钙钛矿太阳电池中,开路电压最高可达1.23 V,效率最高可达20.54%,并且相分离被抑制后的封装钙钛矿太阳电池稳定性显著改善,在一个太阳连续光照500 h后,电池效率仍可保持在初始效率的81.9%(氮气环境,温度40℃)。

窄间隙GMAW咬边缺陷的电弧声信号特征分析与识别

针对窄间隙熔化极气体保护焊(Gas Metal Arc Welding,GMAW)焊道侧壁处局部咬边缺陷检测困难的问题,提出了一种基于电弧声信号特征提取与处理的咬边缺陷在线检测方法。通过分析正常、临界咬边和咬边这3种焊接状态的电弧形态和电弧声信号特征,证实坡口侧壁引起的电弧形态变化是影响电弧声信号变化的重要因素。在此基础上采用小波包时频分析,同时引入特征类间标准差作为评价指标,确定了能有效识别3种焊接状态的敏感特征。采用Sigmoid支持向量机和五折交叉验证建立预测模型,实验结果表明该模型能较好地实现3种焊接状态的预测分类,识别准确率达到96.0%。

GaP的缺陷随温度变化的PAT研究

我们对ＬＥＣ法制成的掺Ｓ的ＧａＰ单晶，从室温至１０００℃，每隔５０℃恒温３０分钟，在Ａｒ气保护下进行热处理．用正电子湮没技术（ＰＡＴ）对样品中的缺陷进行了分析研究．结果指出，随着热处理温度的升高，ＧａＰ中的点缺陷组态发生变化．测试结果表明，正电子湮没寿命可分解为两个寿命．其中捕获态寿命τ２随热处理温度的升高，由３１０ｐｓ变为３３０ｐｓ；进而在高温下变为２８０ｐｓ．相应地捕获强度Ｉ２随温度而发生变化，它反映出ＧａＰ单晶中的空位浓度也在随温度发生变化．

基于气隙缺陷场强分布的绝缘子优化研究

某型号GIS刀闸转轴绝缘子发生放电故障,推测其原因为绝缘子内部出现气隙而导致绝缘劣化。对绝缘子进行优化,并对优化前、后绝缘子中同一形状气隙位于绝缘子不同位置对绝缘子场强分布的影响进行分析,结果显示,当气隙位于电极与树脂交界面和绝缘子中间部位时,对绝缘子场强分布影响较大。对优化后的绝缘子进行了温度、机械-电场老化试验,并通过了工频、雷电冲击试验和工业CT检测的验证。

基于激光扫描的废弃玻璃目标分拣优化方法

废弃玻璃分拣时存在分拣效果差、耗时长的问题,为此提出一种基于激光扫描的废弃玻璃目标分拣优化方法。利用激光扫描获取玻璃点云数据,将原始点云数据加工成切片数据并压缩,通过最小二乘法控制点云数据误差,以此获取所需待分拣区域目标数据。利用图像阈值分割法,通过各目标间的差距度量完成区域图像前景和背景分割,使用四叉树方法分解包含目标的前景图像控制点重建背景,通过高斯滤波器平滑处理背景图像提取废弃玻璃特征,最终采用模板匹配方法寻找废弃玻璃目标,从而实现分拣工作。实验结果表明,所提方法分拣的废弃玻璃与实际结果一致,并且分拣时间低于1.5 s,验证了该方法的分拣效果好,应用价值更高。

窄间隙激光焊研究现状及未来展望

窄间隙激光焊是一种先进的焊接技术,具有焊接厚度大、焊接柔性强、焊后变形小等优点,在厚板结构中得到了广泛的研究。文中全面回顾窄间隙激光焊的历史发展并简要概述窄间隙激光焊的工艺流程。然后深入阐述影响焊接质量的因素并讨论窄间隙激光焊的常见焊接工艺缺陷。此外,总结了优化焊接质量控制策略,可分为光束调制、外部物理场和其他手段。激光摆动被广泛应用于窄间隙激光焊中,电磁及超声辅助也会提升焊缝质量,热丝焊可以提高焊接效率。此外,文中还探讨计算机辅助在窄间隙激光焊中的应用。最后对窄间隙激光焊的未来发展进行了展望。

GaP中反位缺陷的电子结构

本文利用紧束缚的格林函数方法，确定了Ｇａｐ中Ｐ＿（Ｇａ）反位缺陷的波函数为深能级Ｅ的函数。理论给出反位原子上的超精细相互作用常数，同实验符合得很好，定性说明了ＧａＰ中Ｐ＿（Ｇａ）反位缺陷的次近邻原子有向外驰豫的趋势。

基于X射线数字化成像技术的40.5 kV开关柜触头盒质量检测

作为高压开关柜的关键绝缘部件,触头盒主要起绝缘隔离和连接过渡的作用。触头盒发生局部放电会导致绝缘击穿,甚至引发相间短路故障,对开关柜的可靠性运行带来严重威胁。目前对于触头盒产品没有有效的质量检测标准,为此提出了采用X射线数字化成像技术对某40.5 kV开关柜的触头盒进行入网质量检测,并在安装阶段进行检测试验。检测结果发现同批次12件触头盒中有4件内部存在空隙类缺陷,为不合格产品。试验结论表明,采用X射线数字化成像技术检测触头盒的产品质量具有一定的实用性,这也为开关柜内其他绝缘部件的质量检测提供了参考和借鉴。

核电厂主管道窄间隙焊缝射线检验疑似线性缺陷分析

为探究核电厂主管道窄间隙焊缝射线检验出现的疑似线性缺陷的产生机理,采用扫描电镜、原子探针等方法分析了存在疑似线性缺陷的焊缝微观组织与显微硬度,讨论了显微组织中的微细孔隙形成原因,并采用孔隙率表征了微细孔隙分布。研究表明,疑似线性缺陷不是真正的焊接缺陷,存在疑似线性缺陷的焊缝组织均由奥氏体与δ铁素体构成,不同区域的δ铁素体含量基本相同,存在疑似线性缺陷的焊缝的孔隙率为0.06%,高于无疑似线性缺陷区域的0.03%。显微组织中微细孔隙率的差异是导致疑似线性缺陷产生的主要原因,但孔隙率的差异不影响焊缝的显微硬度分布。该研究为类似射线检验出现的疑似线性缺陷提供了评判新思路。

Design of Novel Compact Electromagnetic Bandgap Structures with Enhanced Bandwidth

Two kinds of compact electromagnetic band gap （EBG） structures are designed. A two layer compact EBG structure configured with cross spiral shape line inductors and interdigital capacitors is first presented. Because of its significantly enlarged equivalent inductor and capacitance, the period of the lattice is approximately 4.5% of the free space wavelength. By insetting several narrow slits in the ground plane, the bandwidth of the main bandgap is enhanced by nearly 19%. Further effort has been made for designing a three layer compact EBG structure. Simulation results show that its period is reduced by about 26% compared to that of proposed two layer EBG structure, and the bandwidth of the main bandgap is about 3 times as that of the proposed two layer EBG structure. The detailed designs including a two layer compact 3×7 EBG array with and without defect ground plane and the three layer EBG array are given and simulation results are presented.

Different Feeding Techniques of Microstrip Patch Antennas with Spiral Defected Ground Structure for Size Reduction and Ultra-Wide Band Operation

Different feeding techniques of microstrip patch antennas with different spiral defected ground structures are presented in this paper. The investigated structures illustrate some merits in designing multi-electromagnetic band-gap structures by adjusting the capacitance and changing the inductance through varying the width and length of spiral defected ground structure. Then by applying the three different spirals shapes (one, two and four arms) as the ground plane of microstrip patch antenna with different feeding techniques to create multi or ultra wide-band, improve the antenna gain and reduce the antenna size, it is found that the four arms spiral defected ground structure of microstrip patch antenna with offset feed gives good performance, electrical size reduction to about 75% as compared to the original patch size and ultra-wide bandwidth extends from 2 GHz up to 12 GHz with ?8 dB impedance bandwidth.

新型红外晶体材料磷化镓(GaP)的生长结构缺陷及其性能

磷化镓 (GaP)晶体作为一种表面硬度高 ,热导率大 ,宽波段透过的红外光学材料 ,由于其优良的综合光学、机械和热学性能 ,使其在军事领域及民用高科技领域有着潜在应用的可能性。特别是该晶体材料有可能代替现有的最重要的长波红外材料ZnS ,或者与其形成复合材料 ,是高马赫数导弹窗口材料的选择之一。国外对磷化镓 (GaP)晶体材料已经进行了很长时间的生长研究 ,采用了许多制备方法 ,但多数只能生长磷化镓 (GaP)材料的薄膜或单晶。针对这一情况 ,我们进行了生长工艺的研究 ,选择出适合磷化镓 (GaP)晶体材料生长的条件。磷化镓 (GaP)晶体材料的制备是在真空、低压密封的生长炉中 ,采用一种新颖的气相扩散热交换法进行生长的。在磷化镓 (GaP)晶体的生长过程中 ,工艺条件要求严格控制 ,如生长界面的温场分布 ,温度梯度的大小 ,磷 (P)蒸气的蒸发与扩散速率的控制 ,以及坩埚容器材料的选择等 ,都能导致磷化镓 (GaP)晶体材料的结构缺陷 ,从而严重影响晶体材料的透过性能及其它性能。本文着重讨论了该方法生长磷化镓 (GaP)晶体材料的结构缺陷 ,以及导致各类缺陷的原因及对晶体性能的影响 ,提出了改进工艺生长条件的方法与措施 ,从而对生长出高品质的磷化镓 (GaP)晶体材料有着至关重要的作用。