激光掺杂制作选择性发射极晶体硅PERC电池的工艺研究

基于PERC (Passivated emitter and rear cell)电池的工艺基础,进行了激光掺杂制作选择性发射极晶体硅PERC电池的研究。以现有的PERC电池制造技术路线为基础,激光掺杂制作选择性发射极。研究了经激光掺杂后,选择性发射极对方块电阻、磷扩散结深及表面掺杂浓度、遮光比、激光能量密度、激光脉冲重叠率的影响。利用四探针测量仪、电化学电容-电压法(ECV)、扫描电子显微镜(SEM)、WT2000(μPCD-microwave photo conductivity decay)、二次离子质谱测量仪(SIMS)、WCT120测试仪、光致发光光谱仪(PL)、光谱响应(EQE)、二次元测长仪(Two dimensional length measuring instrument)对试样依次进行了表征。研究结果表明:激光掺杂后的PERC电池在短波波段具有更高的量子效率。方块电阻主要影响了PERC电池的表面复合速率。而PERC电池的开路电压主要取决于方块电阻、激光能量密度、激光脉冲重叠率。短路电流密度主要取决于方块电阻、磷扩散结深及表面掺杂浓度、遮光比、激光能量密度、激光脉冲重叠率。     

ITO薄膜和新型金属化对双面TOPCon电池电性能的影响研究

使用磁控溅射设备制备ITO薄膜和全面积银电极,该文分析了ITO薄膜沉积速率、方块电阻、电阻率和透射率的变化情况,以确定最佳工艺,再对电池的发射极和n型多晶硅钝化性能进行测试分析。使用最佳工艺在TOPCon半成品电池正面和背面沉积ITO薄膜和银电极,测试、分析其对电性能的影响。研究结果表明,当溅射时间为24 min时,电阻率相对较小,透过率对应值大约为88%和86%。当正面光照IV测试时,TOPCon电池背面沉积ITO薄膜和银电极比常规浆料印刷电极的短路电流、填充因子和转换效率分别高了61 mA、1.6%和0.28%,且全面积金属电极与氧化硅层、衬底及多晶硅层的接触电阻满足要求。     

得可新一代电池制造丝网印刷平台全球首发

5月16日,得可太阳能举行了其2012年最新电池制造丝网印刷平台Apollo的全球首发仪式。Apollo先进的自动化技术使堆叠式印刷和选择性发射极工艺的精度达到最优,并为客户提供了高重复性及高性能的印刷体验,而所有这些都在行业领先的紧凑占地面积,单线配置中完成。     

高效单晶硅太阳电池的最新进展及发展趋势

晶体硅太阳电池是目前光伏市场的主流产品,其又可分为多晶硅电池和单晶硅(c-Si)电池。目前,多晶硅电池成本较低,市场份额较大,但其效率较低;单晶硅电池成本相对偏高,但其效率更高,市场份额小于多晶硅电池。随着硅材料和硅片切割技术的进步,单晶硅片的成本持续下降,且未来市场对高效率的高端光伏产品需求日益增长。因此,高效率的单晶硅电池将受到更多的关注。为进一步提高单晶硅太阳电池的效率,近几年的研究工作主要集中于提高硅片质量来降低体缺陷,寻找新型钝化材料来降低表面和界面缺陷,开发先进的减反技术(新型的绒面陷光结构和材料)以提高光的利用率,引入低电阻金属化技术降低串联电阻,优化PN结制备技术以及器件结构等。2014年至今,单晶硅太阳电池的转换效率得到连续突破。目前,最高效率是日本Kaneka公司创造的26.6%,其他效率达到或者超过25%的晶硅电池包括钝化发射极背面局部场接触(PERL)电池、交叉指式背接触(IBC)电池、硅异质结(SHJ)电池、交叉指式背接触异质结(HBC)电池、隧穿氧化层钝化接触(TOPCon)电池、多晶硅氧化物选择钝化接触(POLO)电池等。分析这些典型电池的关键技术可以发现,栅线电极与c-Si的金属-半导体接触复合成为影响电池效率的关键因素。为减小这些复合,一方面通过电池背面局部开孔来减小金属与c-Si直接接触的面积,包括钝化发射极背场点接触(PERC)、PERL、钝化发射极和背面全扩散(PERT)等电池。另一方面则是开发既能够实现优异的表面钝化,同时又无需开孔便可分离与输运载流子的新型载流子选择性钝化接触技术,如SHJ电池、TOPCon电池等。此外,采用交叉指式背接触技术与其他电池结构结合则是最大限度提高光利用率的必然选择,包括IBC电池和HBC电池。本文介绍了当前国际上转化效率达到或超过25%的典型高效单晶硅太阳电池,分别对其器件结构、核心工艺、关键材料等进行了分析,在总结这些高效单晶硅太阳电池各自特点的基础上对该领域的发展前景进行了展望。     

浆料中银颗粒均匀度对太阳能电池性能的影响

为了减小反向漏电流对太阳能电池性能的不良影响,该文通过实验,对比了两款银颗粒均匀度不同的浆料,并将其分别印刷于两组硅片表面;经过各自最优条件烧结后,通过SEM观察了电极与硅片间的接触形成情况;同时,对两组电池片的各项电性能参数进行了对比。结果发现,银颗粒均匀度较差的浆料,会导致较大的反向漏电流,从而降低电池的转换效率;而浆料中银颗粒大小均一、分布均匀的浆料,则可使反向漏电流减小85%以上,有效避免了烧穿的发生,使电池的电性能得以明显提高。     

玻璃中PbO含量对太阳能电池正面银浆欧姆接触性能的影响

正面银浆是晶体太阳能电池金属化的关键材料,玻璃中铅组分在达到银浆与硅片良好的欧姆接触中起着重要作用。用TGA-DSC和SEM对无铅玻璃及含铅玻璃特性进行了表征。结果表明,含铅玻璃Tg低,放热量高,溶Ag能力强,在降温过程中析出的银颗粒数量占优、粒径细小、排列规则、分布均匀,因此有较好的欧姆接触。研究了不同PbO含量的玻璃对不同方阻硅片电性能的影响,结果显示,随着硅片方阻的提高,增加玻璃中PbO含量有助于改善与Si发射极的欧姆接触,但PbO含量过高,溶Ag量过大,玻璃对Si发射极腐蚀较深,导致P-N结破坏严重,漏电较大,Voc下降明显。PbO含量在15%～25%,欧姆接触较好,Voc影响较小,故有较好的电池转换效率。     

非工作状态下贮备电池电性能智能化测试系统的研制

从贮备电池非工作状态下电性能测试的需求出发,构建了智能化测试系统的总体框架,介绍了系统的测试原理,研制出贮存电池电阻智能化测试系统。结果证明该系统实现一次多个参数多个产品的测试及测试数据的自动记录与合格与否自动判读,提升测试过程的安全性与测试效率,为贮备电池电阻检测的智能化提供了保障。     

锂离子电池正极材料微波合成工艺与电性能

本文采用微波合成新方法合成锂离子电池材料LixMn2O4,讨论了微波合成工艺条件如保温时间等对产物物相的影响,结果表明700℃～800℃是微波合成LixMn2O4的适宜温度范围,合成时间为10～15分钟,比常规合成短很多,同时探讨了微波合成与常规固相方法合成正极材料在物相结构及其电性能等方面的差别.讨论影响电性能的因素如:合成温度、配比等.     

高温退火对多晶硅太阳能电池性能的影响

提高多晶硅太阳能电池电性能的一种有效方法——高温退火法,讨论了晶界对太阳能电池性能的影响,并给出了退火后多晶硅薄膜的测试结果。     

NiO/ZnO薄膜太阳能电池的研究进展

综述了近年来国内外NiO/ZnO薄膜太阳能电池的研究进展,重点介绍了有无掺杂的NiO/ZnO薄膜太阳能电池的制备方法及电性能指标,并简要分析了该异质结薄膜太阳能电池存在的问题和未来发展动向,认为未来NiO/ZnO薄膜太阳能电池的研究应集中在通过选择掺杂元素以及引入中间层来提高电学特性.     

Ion implanted crystalline silicon solar cells with blanket and selective emitter

We present an alternative method to form a blanket and selective emitter using a method that implants ion. This avoids several problems such as losing area by laser isolation and wet process for removing phosphosilicate glass formed on silicon substrate during the conventional thermal POCl₃ diffusion process. It was demonstrated that laser isolation is not necessary after the ion implanted solar cells were fabricated. Furthermore, we also fabricated selective emitter solar cells. After studying their characteristics, it was clear that the solar cells with ion implanted selective emitter improved cell efficiency. This is because their blue response increased and their reverse saturation current density decreased. Using an industrially feasible process, solar cell efficiencies of >18.5% on 156 mm × 156 mm using a shallow 100 Ω/sq. emitter and an ion implanted 65 Ω/sq. selective emitter were achieved.     

Fabrication of selective-emitter silicon heterojunction solar cells using hot-wire chemical vapor deposition and laser doping

The Si heterojunction (HJ) solar cells were fabricated on the textured p-type mono-crystalline Si (c-Si) substrates using hot-wire chemical vapor deposition (HWCVD). In view of the potential for the bottom cell in a hybrid junction structure, the microcrystalline Si (μc-Si) film was used as the emitter with various PH₃ dilution ratios. Prior to the n-μc-Si emitter deposition, a 5 nm-thick intrinsic amorphous Si layer (i-a-Si) was grown to passivate the c-Si surface. In order to improve the indium-tin oxide (ITO)/emitter front contact without using the higher PH₃ doping concentration, a laser doping technique was employed to improve the ITO/n-μc-Si contact via the formation of the selective emitter structure. For a cell structure of Ag grid/ITO/n-μc-Si emitter/i-a-Si/textured p-c-Si/Al-electrode, the conversion efficiency (AM1.5) can be improved from 13.25% to 14.31% (cell area: 2 cm × 2 cm) via a suitable selective laser doping process.     

An a-Si:H/SiGe/Si punchthrough heterojunction phototransistors with an thin-Al film

An a-Si:H/SiGe/Si punchthrough heterojunction phototransistors (PTHPTs), responding to a wavelength of 850 nm, have been proposed and demonstrated in this work. The dramatic difference between PTHPTs and conventional heterojunction phototransistors is that the base is completely depleted in the PTHPTs, thus a larger optical gain is achieved due to the lack of a neutral base. Furthermore, the use of low-temperature a-Si:H instead of conventional crystalline silicon, a strained SiGe can be preserved at the interface of base and emitter, allowing ultrashallow junctions and abrupt doping profiles. Another advantage is that the a-Si:H can provide large valence-band discontinuity between base and emitter, avoiding photogenerated holes injected from base to emitter, and hence a larger collector current. In addition, we employed a thin Al-coating covered on the surface of emitter to enhance the collection of photogenerated holes. In comparison to the PTHPTS without the thin-Al coating, the optical gain of PTHPTs with thin-Al coating is increased from 922 to 3970 at 5-V bias voltage, responding to a light source of 850 nm with 0.028 mW.     

T型发射区单晶硅太阳电池的输出特性研究

利用TCAD半导体器件仿真软件对具有T型发射区结构的单晶硅太阳电池进行了仿真研究。全面系统地分析了在不同衬底少子寿命情况下,不同T型发射区深度对太阳电池外量子效率、短路电流密度、开路电压、填充因子及转换效率的影响。仿真结果表明:采用T型发射区结构可在一定程度上提高常规均匀发射区太阳电池的电学性能;T型发射区结构对700~1200nm长波段入射光的外量子效率具有明显的改善作用;当衬底少子寿命一定时,太阳电池短路电流密度、填充因子均随T型发射区深度的增大而增大,而开路电压随T型发射区深度的增大而减小;当T型发射区深度大于80μm时,对于低衬底少子寿命的单晶硅太阳电池,T型发射区结构对其转换效率的改善效果最为显著。     

聚光背结背接触太阳电池发射区半宽度的优化研究

利用TCAD半导体器件仿真软件对中低倍聚光光伏系统中应用的N型叉指背接触(IBC)单晶硅太阳电池的电学性能进行了仿真研究。全面系统地分析了在不同聚光比情况下,单元电池发射区半宽度对聚光IBC太阳电池短路电流密度、开路电压、填充因子及转换效率的影响。仿真结果表明:聚光IBC太阳电池的电学性能受到单元电池发射区半宽度和聚光比的显著影响。在不同的聚光比情况下,存在最优的发射区半宽度,使得聚光IBC太阳电池转换效率最高。随着聚光比的增大,最优的发射区半宽度减小。虽然增大聚光比可提高聚光IBC太阳电池的转换效率,但同时减小了最优的发射区半宽度及参考范围,增加了聚光IBC太阳电池的制备难度。     

掺砷多晶硅边缘场发射阴极阵列的特性研究

提出了一种T形结构的边缘场发射阴极，它具有比通常的场发射体的发射面积大得多的特点。首次采用低压化学气相沉积技术生长内层重掺砷、外层较掺砷的多晶硅薄膜；利用氢氟酸／硝酸／冰醋酸腐蚀液对不同掺砷浓度多晶硅选择性腐蚀的特点，成功制备了T形结构的多晶硅边缘场发射阵列（FEA）；本方法对于制备类似结构的边缘场发射器件有意义。在此基础上建立了三极管几何模型，最后采用有限差分法对该三极管模型进行了静电分析。     

Controlling analyte electrochemistry in an electrospray ion source with a three-electrode emitter cell

The inherent electrochemistry occurring at the emitter electrode of an electrospray ion source was effectively controlled by incorporating a three-electrode controlled-potential electrochemical cell into the controlled-current electrospray emitter circuit. Two different basic cell designs were investigated to accomplish this control, namely, a planar flow-by working electrode and a porous flow-through working electrode design, each operated with a potentiostat floated at the electrospray high voltage. Control of the analyte electrochemistry was tested using the indole alkaloid reserpine, which is often used to test the specifications of electrospray mass spectrometry instrumentation. Reserpine was relatively easy to oxidize (E(p) = 0.73 V vs Ag/AgCl) in the acidic electrospray medium (acetonitrile/water 1:1 v/v, 5.0 mM ammonium acetate, 0.75 vol % acetic acid) and was oxidized when the conventional electrospray emitter was used at low solution flow rate. With the proper cell auxiliary electrode configuration and adjustment of the working electrode potential, it was found that reserpine oxidation could be "turned off" at flow rates as low as 2.5 microL/min as well as at flow rates as high as 30-40 microL/min. Just as important, it was also possible to "turn on" essentially 100% oxidation of reserpine in this flow rate range. The area of the auxiliary electrode along with flow rate, which affect mass transport of analytes to this electrode, were found to be critical in controlling the electrochemical reactions in the emitter cell. Such control over analyte electrochemical reactions in the emitter has been difficult or impossible to achieve with a conventional electrospray emitter. This control is paramount in obtaining experimental results free from electrochemically generated artifacts of the analyte or in exploiting electrochemical reactions involving the analyte to analytical advantage.     

Development of a hot-wire chemical vapor deposition n-type emitter on p-type crystalline Si-based solar cells

We have developed a p-type, crystalline Si-based solar cell using hot-wire chemical vapor deposition (HWCVD) n-type microcrystalline Si to form an n-p junction (emitter). The CVD process was rapid and a low substrate temperature was used. The p-type Czochralski (CZ) c-Si wafer has a thickness of 400 μm and has a thermally diffused Al back-field contact. Before forming the n-p junction, the front surface of the p-type c-Si was cleaned using a diluted HF solution to remove the native oxides. The n-type emitter was formed at 220 °C by depositing 50 Å a-Si:H and then a 100 Å μc-Si n-layer. The total deposition time to form the emitter was less than 1 min. The top contact of the device is a lithograph defined and isolated 1×1 cm² and 780 Å indium tin oxides (ITO) with metal fingers on top. Our best solar cell conversion efficiency is 13.3% with V_oc of 0.58 V, FF of 0.773, and J_sc of 29.86 mA cm⁻² under one-sun condition. Quantum efficiency (QE) measurement on this solar cell shows over 90% in the region between 540 and 780 nm, but poor response in the blue and deep red. We find that the ITO top contact that acts as an antireflection layer increases the QE in the middle region. To improve the device efficiency further, J_sc needs to be increased. Better emitter and light trapping will be developed in future work. The cell shows no degradation after 1000 h of standard light soaking.     

电离规的新进展

介绍了传统热阴极电离规和冷阴极电离规的发展历程和研究现状、新型场发射阴极(微尖型阴极和碳纳米管阴极)在电离规中的应用、小型化电离规的发展和国内在超高/极高真空电离规研究方面取得的成果和现状。重点回顾了碳纳米管阴极电离规和小型化电离规在近年来取得的重大成就。由于碳纳米管具有长径比大、曲率半径小、机械特性强、导电性好和优异的场发射特性,使得其作为电离规阴极有望解决传统冷阴极电离规在低压下不能放电的困难和传统热阴极电离规的热出气效应,从而为极高真空测量提供一种解决途径。     

Selective boron diffusion without masking layer using boric acid for solar cell emitter formation

In this article, we have used boric acid as a source to form the solar cell emitter in a selective way. Moreover, in order to optimize the process, the conditions of boron diffusion were investigated. It was found that for 5% boric acid in deionized (DI) water, the spinning speed of 3000 rpm for 15 s and dry-out process at 200?°C are the most appropriate conditions. Additionally, by using the boric acid source, a selective doping method was developed in this study. Therefore, we have demonstrated that it is possible to perform both light and heavy (under contacts) dopings on different areas of the wafer without any extra masking layer (e.g. silicon dioxide) and undergoing only one drive-in process.