网版参数对单晶硅太阳电池栅线印刷的影响

常规太阳电池表面由于扩散浓度高,导致载流子复合严重,电池转换效率很难提高,目前高方阻密栅线工艺是提高产业化太阳电池转换效率的重要途径之一。通过扩散工艺很容易实现高方阻,难点在于优化电池正面网版参数,得到最优的栅线形貌及高宽比。针对该问题,基于丝网印刷网版参数,研究不同感光胶EOM膜厚、网版纱度、网版目数、下墨量对单晶硅太阳电池栅线印刷的影响,使用扫描电子显微镜(SEM)和激光共聚焦显微镜(LSM)观察了栅线的形貌、高宽比。结果表明感光胶并非越厚越好,当感光胶厚度达到20μm时栅线的高宽比达到最优,此时电池的转换效率最高;当网版目数、线径相同时纱厚较小的网版印刷出的栅线较均匀;当网版目数、线径均不同时,下墨量大的网版具有优势。     

聚苯乙烯微球辅助制备超薄PERC太阳电池

利用旋涂法将自制的聚苯乙烯(PS)微球涂覆到不同厚度的单晶硅片上,作为钝化发射极和背面电池(PERC)的背接触开口的掩模,然后用快速热退火工艺使PS微球挥发形成PERC电池的背接触开口,最后用磁控溅射在PERC电池背面生长一层Ag电极。利用该方法制备了面积为40 mm×40 mm、厚度分别为40、55和70μm的三种超薄单晶PERC太阳电池。制备的超薄太阳电池未出现任何翘曲。超薄太阳电池的电流密度-开路电压(Jsc-Voc)曲线和外量子效率(EQE)曲线测试结果表明,随着电池厚度的减小,电池的转换效率随之下降。其中,40μm厚的电池转换效率最高达13.6%,平均转换效率为13.3%,并展现出良好的柔韧性,极限弯曲角度达到135°。     

P型双面单晶硅太阳电池单元宽度的优化北大核心CSCD

在正面光照和背面光照两种条件下,利用半导体器件仿真软件分析了单元电池宽度对产业化P型双面单晶硅太阳电池电学性能的影响。为进一步提高双面太阳电池光电转换效率,对单元电池宽度进行了优化。仿真结果表明,在正、背面光照条件下,随着单元电池宽度的增大,双面电池短路电流密度均增大;当单元电池宽度较小时,正、背面短路电流密度增大较迅速。随着单元电池宽度的增大,正、背面开路电压均增大,而正、背面填充因子先增大后减小。当正、背面入射光强一定时,存在最优的单元电池宽度,使得双面太阳电池转换效率达到最大值。随着单元电池宽度的增大,正面和背面光电转换效率均先增大后减小,但正、背面光照条件下的最优单元宽度不同。当单元电池宽度一定时,存在最优的正、背面栅电极间距。     

PERC背钝化结构提升多晶硅太阳电池的光电转换性能研究

在工业产线上制备了PERC结构的多晶硅太阳电池,并研究了在电池背表面引入PERC背钝化结构对其光电转换性能的影响。结果表明:PERC背钝化结构能够提升电池的短路电流和开路电压,光电转换效率超过了20%。结合光学仿真及分析电池的关键光电参数知,其光电转换性能改善的原因可归结为PERC背钝化结构降低了长波太阳光子在背铝电极的寄生吸収损失和光生载流子的背表面复合损失。PERC背钝化结构能够提升多晶硅太阳电池的光电转换效率,并且其制备工艺与传统产线兼容,是一种优选的产业电池结构。     

背接触太阳电池的背面设计优化

利用quokka3仿真软件建立三维模型,对n型叉指背接触(IBC)单晶硅太阳电池的单元电池结构设计和栅线参数进行了仿真优化,并通过激光和丝网印刷进行了实验验证。实验结果表明,在不同IBC单元电池结构设计下,当p+发射区与n+背表面场区的宽度比值为4时,IBC太阳电池效率比宽度比值为2.3时的高0.11%。可通过减小单元电池宽度,增大p+发射区与n+背表面场区的宽度比值来获得更高的IBC太阳电池效率。在相同单元电池结构设计下,当细栅线宽度从40μm增加到60μm时,IBC太阳电池效率能够提高0.18%。且相比4主栅,6主栅IBC太阳电池效率可提高0.09%。因此,增加副栅线宽度和主栅线数量有利于IBC太阳电池效率的提升。     

丝网印刷光伏电池正面电极银浆的流变学研究

高效光伏电池要求正银电极"细栅密植",要获得栅线细和形貌好的正面电极,对导电银浆的要求是易过网、流平性好和高宽比大,即对浆料的流变学性能有特殊要求.印刷是一个动态过程,故传统的测试参数黏度和触变指数不能完全应用于对浆料印刷的指导.主要探讨导电银浆的流变学性能与实际印刷的关系,开发了简单的实验测量模式,通过对几种商业浆料的对比测试,发现该方法行之有效.同时,利用复杂模量和相位角可解释浆料的印刷和高效评价浆料的印刷性能.     

单晶硅电池表面织构与光电特性的关系

针对在单晶硅片表面制备陷光织构可提高吸光率,但同时将导致光生伏特效应被削弱的问题,定义了电池的光学特性系数和电学特性系数,以表征电池光电特性。通过采用不同的化学制绒工艺参数,在单晶硅片表面获得不同尺寸的表面织构,分析了织构平均高度对电池光电特性和转换效率的影响规律。结果表明:随着单晶硅片表面织构平均高度的增大,单晶硅电池的光学特性系数呈现先升高再降低的规律,电学特性系数呈现逐渐减小的规律;基于中型金字塔绒织构的硅电池同时兼顾了光学特性和电学特性,得到最高的光电转换效率为19.49%。     

高效单晶硅PERC局部背表面场及接触的优化

钝化发射极和背面电池(PERC)技术可有效提高电池效率,在常规p型电池的背面增加了钝化层,并形成了局部背表面场(LBSF)结构.介绍了PERC结构电池的工艺流程,分析了背场(BSF)的形成机制,主要研究了PERC的LBSF制备工艺及影响要素.通过采用激光消融后清洗方法改善了背表面形貌,平整的背表面形貌有利于BSF的形成.通过优化烧结条件,电池的填充因子得到改善.讨论了激光开槽图形对开路电压以及填充因子的影响.测试结果表明,PERC转换效率绝对值提升了0.9％,达到20.83％,填充因子达到80.7％.     

n型异质结背接触太阳电池前表面的场钝化

利用Silvaco-TCAD仿真软件建立二维模型,对n型异质结背接触(HBC)单晶硅太阳电池前表面场进行模拟研究。通过在n型单晶硅衬底正面分别引入一层较薄的本征非晶硅层和一层n+非晶硅层对电池前表面进行高质量的场钝化,分析了n+非晶硅层的厚度和掺杂浓度以及本征非晶硅层的厚度和带隙宽度对电池电学性能的影响。模拟结果表明:当n+非晶硅层厚度小于6 nm,掺杂浓度为1×1019 cm-3,本征非晶硅层的厚度为3 nm,带隙宽度大于1.5 eV时,电池前表面实现了良好的场钝化效果,HBC太阳电池获得了24.5%的转换效率。     

皮秒脉冲激光辐照太阳能电池损伤特性实验研究(特邀)

以皮秒脉宽激光多脉冲损伤太阳能电池为背景,通过激光烧蚀电池前后表面形貌、电池伏安特性、电致发光特性获得损伤特性。采用脉宽15 ps、波长1 064 nm皮秒脉冲激光辐照三结GaAs太阳能电池进行实验。通过重频调节改变激光辐照功率,对太阳能电池栅线与非栅线部位在激光辐照下的损伤特性进行分析。实验发现辐照非栅线部位时,尽管激光光斑较小,但电池内部材料已经发生损伤,主要是由于电池内部材料有序结构的破坏逐渐增大,尤其是激光功率越高时,内部损伤面积越大。当激光辐照栅线部位时,栅线部位受热熔断会极大影响太阳能电池对载流子的吸收,从而降低电池的光电转换能力,进而影响太阳能电池的电性能,使得激光辐照栅线部位损伤效果强于辐照非栅线部位。     

Photonic sintering of inkjet printed current collecting grids for organic solar cell applications

ITO-free organic solar cells with inkjet printed current collecting grids are demonstrated. For sintering those grids, thermal treatment and its faster alternative, photonic flash sintering, are applied and the characteristics of the resulting metal structures are compared with each other. The electrical potentials and resulting currents in the devices with different sintering conditions are calculated. The flash sintered current collecting grids exhibit clear advantages over thermally sintered grids in terms of geometry and conductivity. Similar conductivities are obtained after 5 s of flash sintering and 6 h of thermal sintering. This finding demonstrates the great potential of flash sintering for the roll-to-roll manufacturing of printed organic solar cells on flexible substrates.     

Electrical and shading power losses of decorative PV front contact patterns

Visual appeal is an important criterion for the acceptance of photovoltaic modules in facades and roofs of buildings, or in village electrification. With crystalline silicon solar cells, the busbars are often seen as disturbing. Therefore, we tried to convert the busbars into an attractive feature by incorporating artistic design. Busbars should have an eye-catching effect. But increased shading or non-optimal finger layout should have no significant effect on efficiency. In the present work we calculated the different losses of newly designed front contact patterns. The design concept was to have a few basic front metallisation grids at the cell level, which would permit a large number of different appearances at the module level. Fifteen new metallisation patterns were compared to the standard metallisation grid regarding the differences in shading and in the electrical losses. Nine of the new patterns are variations of the well known two-busbars scheme. Two patterns have connection points in the middle of each side of the square cell and a completely asymmetric inner layout. This leads to a large number of possibilities of irregular looking modules, not unlike stone or broken glass. Another one is designed to create the appearance of a hexagon web at the module level. Three other cells are designed to create an ‘art-deco’ pattern when combined to a module. By taking into account resistive losses in the emitter layer, in the fingers and in the busbars, and contact losses between fingers and emitter layer, as well as shading losses, we find that the efficiency of a cell with the worst pattern would be only 0·71% absolute below that of a cell with standard pattern and an efficiency of 13·80% at 1-sun conditions (1000 W/m²). Artistic design of the busbar layout of crystalline silicon solar cells can therefore be achieved without an undue decrease of conversion efficiency. Copyright © 1999 John Wiley & Sons, Ltd.     

Electrodeposited zinc grid as low‐cost solar cell front contact

This paper presents an innovative low‐cost electrodeposition process to grow metallic zinc grids as a front contact for Cu(In,Ga)(Se,S)₂ (CIGS) and silicon heterojunction solar cells as an alternative to complex and expensive monolithic integration and silver screen printing techniques respectively. Morphological and electrical properties of the grid have been investigated and compared with a reference evaporated one. High quality and conformal zinc grids have been deposited showing very high growth rates up to 3.3 µm min⁻¹. Zinc grid is successfully deposited as front electrode for CIGS solar cells that are fabricated by a variety of deposition processes. Efficiency (16.3%) is achieved without antireflection coating on a 0.5 cm² co‐evaporated absorber and 14.8% on an electrodeposited one. Using electrodeposition for the growth of the doped ZnO film as well, a 14.1% efficiency is demonstrated on an all‐wet solar cell only composed of layers deposited by atmospheric methods—from absorber to metallic grid. The process is then applied to a 4.2 cm² cell as a first step toward large‐scale application. Finally, a zinc grid is deposited on a 0.5 cm² silicon heterojunction showing a promising 17% efficiency. Copyright © 2016 John Wiley & Sons, Ltd.     

金属网栅电磁屏蔽窗口薄膜的设计与制备

通过光刻掩膜技术、电阻热蒸发沉积技术制备电磁屏蔽窗口金属网栅薄膜,研究金属网栅的红外透射率和电磁屏蔽效能。为了能有效地屏蔽电磁波,使用CST Studio Suite电磁仿真软件设计不同周期、线宽的金属网栅,采用光刻掩膜技术、电阻热蒸发技术在双面抛光单晶硅基片上完成线宽为30μm,周期分别为350μm、450μm、550μm、650μm、750μm的金属网栅薄膜的制备。采用真空型傅立叶红外光谱仪和矢量网络分析仪分别对不同结构参数金属网栅薄膜的光谱特性和电磁屏蔽效能进行测试。结果:实现在双面抛光单晶硅基底上制备的网栅在12~18 GHz频段内,网栅的电磁屏蔽效能均达到12 dB以上。在3~5μm波段的透射率损失仅为8%。为了得到既具有高透光率,又具有强电磁屏蔽效能金属网栅薄膜需要合理设计金属网栅的线宽和周期。制备过程中网栅的光学-电学特性不仅受周期和线宽影响,掩膜板的加工精度、金属网栅的加工缺陷等也会造成不同程度的影响。     

High‐Temperature Contact Formation on n‐Type Silicon: Basic Reactions and Contact Model for Seed‐Layer Contacts

Contact formation on n‐type silicon, especially using a high‐temperature process, has been the subject of research for more than 40 years. After its application in microelectronics, n‐type silicon is widely used in silicon solar cells as the emitter layer. The formation of a low ohmic contact grid using an industrially feasible process step is one of the key features required to improve the solar‐cell efficiency. The contact materials, typically deposited in a printing step, have to fulfil several functions: opening the dielectric antireflection layer and forming an intimate metal‐semiconductor contact with good mechanical adhesion and low specific contact resistance. As the used contact inks typically contain several functional materials, such as silver and a glass frit, the detailed contact formation is still not entirely understood. Therefore, the chemical reactions during the contact firing process have been studied in detail by thermogravimetric differential thermal analysis in combination with mass spectroscopy. Based on these studies, a contact ink has been developed, optimized and tested on silicon solar cells. In this paper, the mechanism of the etching process, the opening of a dielectric layer, the influence of different atmospheres and the impact of the glass‐frit content are investigated. The observed microscopic contact structure, the resulting electrical solar‐cell parameters and the studied reactions are combined to clarify the physics behind the high‐temperature contact formation.     

深槽LIP太阳能电池栅线电极技术

介绍了深槽LIP太阳能电池栅线电极的制造方法,对LIP工艺及装置进行了详细的说明。通过试验表明,用新工艺制造的太阳能电池片的转换效率可达19.4%。讨论了与传统工艺相比较,深槽LIP太阳能电池片在光学和电学性能上的提升机理。     

Impedance characteristics of power distribution grids in nanoscale integrated circuits

The essential design characteristic of nanoscale integrated circuits is increased interconnect complexity. Conductors at different levels of the interconnect hierarchy have highly different physical and, consequently, electrical characteristics. These interconnect lines also exhibit inductive behavior due to enhanced switching speed of nanoscale devices, making interconnect design and analysis difficult. The design of robust and area efficient power distribution networks for high-speed integrated circuits has therefore become a challenging task. The impedance characteristics of multilayer power distribution grids and the relevant design implications are the subject of this paper. The power distribution network spans many layers of interconnect with disparate electrical properties. Unlike single-layer grids, the electrical characteristics of multilayer grids vary significantly with frequency. As the frequency increases, a large share of the current flow is transfered from the low-resistance upper layers to the low-inductance lower layers. The inductance of a multilayer grid therefore decreases with frequency, while the resistance increases with frequency. The lower layers of multilayer power grids provide a low-inductance current path, significantly reducing the grid impedance at high frequencies. Multilayer power distribution grids extend to the lower interconnect layers, exhibiting superior high-frequency impedance characteristics as compared to power distribution grids built exclusively within the upper, low-resistance metal layers. A significant share of metal resources to distribute the global power should therefore be allocated to the lower metal layers. An analytic model is also presented to determine the impedance characteristics of a multilayer grid from the inductive and resistive properties of the comprising individual grid layers.     

掺硼p型晶硅太阳电池LID恢复研究

设计了一种基于绝缘层上硅（SOI）的推挽式硅-有机物混合（SOH）马赫-曾德干涉型（MZI）电光调制器。利用薄膜模式匹配法对槽波导（slot）的光场分布进行了仿真分析,优化后得到了限制因子为0.32的slot波导结构。采用推挽式马赫-曾德干涉仪结构,并在相移臂嵌入LX M1非线性有机材料,得到半波电压-长度积Vπ·L为0.885V·mm、电学响应带宽fRC可达123.2GHz、开关速度为8.11ps的SOH调制器结构。利用基于本征有限元法求解麦克斯韦方程,对共平面波导电极系统进行了计算仿真,获得了特性阻抗接近50Ω、高频速率匹配的电极结构。 更多还原