晶体硅太阳电池双层电极优化分析与实验研究

相对于单层电极结构,优化的前表面双层电极能够明显减小功率损失,改善晶体硅太阳电池的电学特性．本文对晶体硅太阳电池的双层电极进行了优化分析和实验研究.通过扫描电子显微镜观测将双层电极的截面抽象为更接近于实际的半椭圆型,建立了太阳电池前表面的双层电极模型,理论分析了双层电极的电学损失和光学损失.结合丝网印刷后光诱导电镀太阳电池的实验,得到了理论和实验上的最优化光诱导电镀增厚电极厚度与丝网印刷电极宽度的关系.所得到的理论和实验结果符合良好.由于并不涉及电极制备的具体技术,双层电极理论模型普遍适用于多种类型的双层电极结构.     

MgB2各向异性光学性质的第一性原理研究

使用密度泛函第一性原理研究了超导体MgB2单晶各向异性的光学性质.在描述光学性质的基本理论和计算方法的基础上,计算了MgB2的光电导谱、反射谱以及电子能量损失谱,并通过MgB2的各个原子分解态密度图对所得到的反射谱和损失谱的各个谱峰做了详尽地分析.从光电导谱上来看,x方向与z方向有着很大差别,而在反射谱与电子能量损失谱中,x方向与z方向的特征峰位置都是相互符合的.从光导谱来看,沿x方向的第一个带间吸收峰出现在20000 cm-1处,而沿z方向出现在40000 cm-1处.考虑到温度效应对其光学性质的影响,在计算光学矩阵元时加入Lorentz展宽δ=0.10 eV.计算结果和最近实验结果有比较好的一致,只是带间吸收谱峰位置和实验之间存在约1000cm-1(～0.124 eV)的差别.总体上该研究的计算结果从定性上和定量上都与最新各向异性光电导实验结果在误差范围内符合很好.     

钙钛矿/硅异质结叠层太阳电池:光学模拟的研究进展

近几年,钙钛矿/硅异质结叠层太阳电池发展迅速,效率已经从13.7％提升到29.1％.由于叠层电池器件的制作工艺复杂,而叠层太阳电池中的光学损失对转换效率的影响很大,所以通过光学模拟进而获得高效电池至关重要.本文首先从商业软件和自建模型两方面概述了光学模拟的方法,接着从反射损失和寄生吸收两方面针对光学模拟研究进展进行了总...     

MgB2各向异性光学性质的第一性原理研究

使用密度泛函第一性原理研究了超导体MgB₂单晶各向异性的光学性质.在描述光学性质的基本理论和计算方法的基础上,计算了MgB₂的光电导谱、反射谱以及电子能量损失谱,并通过MgB₂的各个原子分解态密度图对所得到的反射谱和损失谱的各个谱峰做了详尽地分析.从光电导谱上来看,x方向与z方向有着很大差别,而在反射谱与电子能量损失谱中,x方向与z方向的特征峰位置都是相互符合的.从光导谱来看,沿 关键词： 超导体 电子结构 光学性质     

晶体硅太阳电池表面纳米线阵列减反射特性研究

为增强晶体硅太阳电池的光利用率, 提高光电转换效率, 研究了硅纳米线阵列的光学散射性质. 运用严格耦合波理论对硅纳米线阵列在310—1127 nm波段的反射率进行了模拟计算, 用田口方法对硅纳米线阵列的表面传输效率进行了优化. 结果表明, 当硅纳米线阵列的周期为50 nm, 占空比为0.6, 高度约1000 nm时减反射效果最佳; 该结构在上述波段的平均反射率约为2%, 且在较大入射角度范围保持不变. 采用金属催化化学腐蚀法, 于室温、室压条件下在单晶硅表面制备周期为60 nm,占空比为0.53, 高度为500 nm的硅纳米线阵列结构, 其反射率的实验测试结果与计算模拟值相符, 在上述波段的平均反射率为4%—5%, 相对于单晶硅35%左右的反射率, 减反射效果明显. 这种减反射微结构能够在降低太阳电池成本的同时有效减小单晶硅表面的光反射损失, 提高光电转换效率.     

Zn1-xMgxO电子结构及光学性质的第一性原理GGA+U方法研究

Mg掺杂ZnO形成的固溶体Zn_1-xMg_xO（ZMO）（0 ≤ x ≤ 0.25）是一种带隙较宽、电子学性质可调控的半导体材料,在薄膜太阳电池及光电设备的透明电极等方面具有重要的应用价值。基于密度泛函理论下的第一性原理超软赝势方法,采用GGA+U计算了ZMO的电子结构和光学性质。计算结果表明,随着x值的增加,ZMO的禁带宽度由x=0时的3.32 eV增加到x=0.25时的3.78 eV;光吸收边及反射谱和能量损失谱均发生明显蓝移,峰值存在于紫外光区。计算结果与实验结论相符合。     

基于微米SDOCT的玻璃亚表面缺陷散射系数测量

用搭建的微米谱域光学相干层析(SDOCT)系统对玻璃亚表面缺陷进行了深度分辨率、非接触、非破坏性测量,并用建立的单次散射模型对得到的断层图像进行计算,得到玻璃亚表面缺陷的散射系数。实验结果表明,利用散射系数可以有效区分玻璃亚表面不同深度的损伤结构。玻璃亚表面散射系数的深度分辨率测量有利于对玻璃亚表面缺陷光学特性的分析,对于精密光学元件的加工和检测具有重要意义。     

玻璃表面层对薄膜光学参数测量的影响

利用p偏振光在镀膜平板玻璃前后表面反射光强比γ与膜层光学参数之间的密切关系,给出了玻璃表面层的光学参数分布。对典型的薄膜系统-单面镀膜与双面镀膜两种情况,理论分析了玻璃表面层对薄膜光学参数测量的影响。实验上对PMTES和SnO₂薄膜参数进行了测量,仅当计及玻璃表面层作用时,反射光强比γ的角度调制曲线才与理论拟合结果相吻合.     

GaN载流子浓度和迁移率的光谱研究

用红外反射光谱的方法对生长在蓝宝石衬底上的α-GaN外延薄膜的载流子浓度和迁移率进行了研究.通过测量蓝宝石衬底和不同Si掺杂浓度的一系列GaN外延膜的远红外反射谱并进行理论计算和拟合,得到GaN中的声子振动参量和等离子振荡的频率及阻尼常量,并由此计算得到其载流子浓度和迁移率.计算结果,红外方法得到的载流子浓度与Hall测量相一致,但迁移率比Hall迁移率要低约二分之一.同时红外谱与喇曼谱上明显观察到LO声子与等离子体激元耦合模,(LPP)随掺杂浓度的变化. 关键词： α-GaN外延薄膜 红外反射光谱 载流子浓度 迁移率 LO声子与等离子体激元耦合模 Raman光谱     

玻璃表面层光学参数分布的研究

利用并改进平板玻璃两面Ｐ偏振光反射光强比的测量来确定玻璃表面光学参数的方法，测量了平板玻璃两面Ｐ偏振光反射光强比γ与入射角θｉ的关系曲线，运用新的表面层模型进行数据模拟，获得了表面层的光学参数分布。     

21.2%‐efficient fineline‐printed PERC solar cell with 5 busbar front grid

We evaluate industrial‐type PERC solar cells applying a 5 busbar front grid and fineline‐printed Ag fingers. We obtain finger widths down to 46 µm when using a stencil with 40 µm opening for the finger print, whereas the busbar is printed in a separate printing step with a different Ag paste (dual print). This compares to finger widths of 62 µm to 66 µm when applying print‐on‐print. The 5 busbar front grid with the best dual print process reduces the shadowing loss of the front grid to 4.0% compared to 5.8% for a conventional 3 busbar front grid printed with print‐on‐print. The 1.8% reduction in shadowing loss results in equal parts from the reduced finger width with dual print as well as from a reduced total busbar width of the 5 busbar design. The resulting PERC solar cells with 5 busbars demonstrate independently confirmed conversion efficiencies of 21.2% compared to 20.6% efficiency of the 3 busbar PERC solar cell. The increased conversion efficiency is primarily due to an increased short‐circuit current resulting from the reduced shadowing loss. To our knowledge, 21.2% conversion efficiency is the highest value reported so far for industry typical silicon solar cells with printed metal front and rear contacts. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

Studies on the polycrystalline silicon/SiO_2 stack as front surface field for IBC solar cells by two-dimensional simulations

Interdigitated back contact(IBC) solar cells can achieve a very high efficiency due to its less optical losses. But IBC solar cells demand for high quality passivation of the front surface. In this paper, a polycrystalline silicon/SiO_2 stack structure as front surface field to passivate the front surface of IBC solar cells is proposed. The passivation quality of this structure is investigated by two dimensional simulations. Polycrystalline silicon layer and SiO_2 layer are optimized to get the best passivation quality of the IBC solar cell. Simulation results indicate that the doping level of polycrystalline silicon should be high enough to allow a very thin polycrystalline silicon layer to ensure an effective passivation and small optical losses at the same time. The thickness of SiO_2 should be neither too thin nor too thick, and the optimal thickness is 1.2 nm.Furthermore, the lateral transport properties of electrons are investigated, and the simulation results indicate that a high doping level and conductivity of polycrystalline silicon can improve the lateral transportation of electrons and then the cell performance.     

Noise screening effects of balconies on a building facade

The insertion loss and its spectrum due to a rectangular balcony on a building facade in the presence of sound reflection and scattering from adjacent balconies were examined using a scale model. The front panel of the balcony dictates the screening performance, while the side walls of the balcony are found to be insignificant. Balconies without a front panel do not provide acoustic protection in the presence of upper balcony reflection, especially for a distant noise source. Sound amplifications are also observed in many cases. In addition, the shapes of the insertion loss spectra are found to depend on the elevation angle of the balcony. Significant correlations between the A-weighted balcony insertion losses with this angle are found in the absence of upper balcony reflections. With such reflection, an angle defined using the balcony configuration and source position correlates within engineering tolerance to the insertion losses.     

EAST装置微波反射成像系统光学性能评测

用宽为1cm的金属反射平面对EAST装置上96道(极向12道×径向8道)微波成像反射计的前端接收光路的道间距和探测光斑半径进行了测试,结果与仿真结果较为一致。用极向旋转的金属轮面作为反射面,研究了非理想光学条件下反射面旋转所引入的多普勒频移,结果与模拟值吻合。     

Dielectric microconcentrators for efficiency enhancement in concentrator solar cells

Metal fingers typically cover more than 10% of the active area of concentrator solar cells. Microfabricated dielectric optical designs that can completely eliminate front contact shading losses are explored. Essentially no microconcentrator optical losses need be incurred, series resistance losses can be reduced, and net efficiency gains of roughly 15% (relative) are realistic.     

Computational analysis of metamaterial–aluminum–silicon solar cell model

In this paper, the optical parameters of an improved waveguide structure for a more efficient silicon solar cell are studied. Despite its favorable electronic, physical, and chemical properties, silicon remains a poor absorber of light. The optical losses due to the reflection at the air/glass interface of the cell and the transmission at its back are other factors, which limit the cell conversion efficiency. Consequently, several mechanisms for light trapping capable to increase the collection of the incident photons as electrical current and to decrease the transmission loss, have been developed. In this context, we propose a multilayer waveguide structure in which the sunlight is guided by a metamaterial layer and the transmission loss is eliminated by an aluminum back reflector. The reflection and transmission coefficients are derived by using the Generalized Transfer Matrix Method. The application of the law of conservation of energy allowed the determination of the absorption coefficient. These optical parameters are examined for several angles of incidence for s-polarized light, p-polarized light and unpolarized light. Simulation results show a significant reduction of reflection and a complete suppression of transmission.     

金属光栅用于增强非晶硅薄膜太阳能电池光吸收率研究

提高太阳能电池光电转换效率的一个重要途径就是提高它的光子吸收能力。在传统非晶硅薄膜太阳能电池中加入了金属光栅,设计出一种新的复合电池结构。基于严格耦合波分析矢量衍射理论计算了该结构的吸收光谱和增强因子;讨论了光栅宽度、入射光角度和入射光偏振态对吸收的影响。结果显示,设计的太阳能电池结构能够显著提高光的吸收率,在TM偏振光入射条件下,该结构的吸收增强因子最高可达40%;在其他偏振态光线入射时,其吸收增强因子也可达到16%左右。     

Transmission characteristics of optical waveguide corners

Two-dimensional dielectric waveguide corners with air reflector or metal reflector have been investigated by means of the method of plane-wave expansion, which has the advantage of being compact for optical integrated circuit applications. The operating principle of these waveguide corners is based on the total internal reflection or large partial reflection. The corner losses and field profiles are presented for various waveguide parameters. It is found that the corner loss can be small if the waveguide corner is properly fabricated.