低成本、高效率晶硅太阳电池的研究

晶硅太阳电池的发展仍然以降低成本、提高效率为主题,围绕这一主题发展出来各种电池结构。文章概述了目前几种转化效率超过20%并且可实现低成本的电池结构,这些电池包括异质结本征薄层(HIT)电池、叉指状背接触(IBC)电池、金属绕通(MWT)电池及发射区绕通(EWT)电池。通过对这几种电池结构的利弊进行分析讨论,总结了各类电池制备所面临问题以及可能的解决方案,为今后低成本、高效率太阳电池的研究提供一些有益的借鉴。     

基于高效太阳电池的光诱导镀技术

介绍了光诱导镀(light-induced plating,LIP)应用于太阳电池的背景、发展历史及其工作原理。论述了光诱导镀技术对太阳电池性能的影响,并重点探讨了光诱导镀技术对太阳电池前表面电极接触性能的改善效果。同时,还讨论了光诱导镀技术应用于铝背表面场(Al-BSF)和激光烧制接触(laser fired contact,LFC)两种高效太阳电池上所取得的成果。当接触电阻成为串联电阻中的主要成分时,光诱导镀能够降低接触电阻、提高填充因子,从而提高电池的效率。光诱导镀特别适合于改善串联电阻较大的电池,利用光诱导镀也可以重新优化电池的烧结条件,得到更高的电池效率。     

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°。     

PERC结构多晶硅太阳电池的研究

高效、低成本是目前硅太阳电池追求的主要目标。多晶硅太阳电池成本低,但其电性能较差。背面钝化及局部背接触是提高多晶硅太阳电池电性能的主要技术。通过采用SiO2/SiNx叠层膜作为背钝化介质层,依次经过背面开槽、丝网印刷、烧结形成背面局部接触,制备钝化发射极和背表面电池(PERC)结构多晶硅太阳电池。采用恒光源I-V特性测试系统测试其电性能,结果表明:较之常规铝背场多晶硅太阳电池,PERC结构电池在开路电压Voc、短路电流密度Jsc、转换效率η方面分别提高了13 mV、1.8 mA/cm2和0.67%(绝对值),其转换效率达到17.27%。PERC结构多晶硅电池采用了常规丝网印刷工艺,有利于实现高效多晶硅电池的产业化生产,具有很高的实际意义。     

多孔硅的不稳定性对太阳电池的影响

研究了多孔硅（PS）的特性及其在太阳电池上的应用,并对PS太阳电池性能以及由于PS的不稳定性对电池产生的影响进行了研究。实验表明,将PS的光致发光（PL）以及减反射特性应用于太阳电池能有效提高电池的效率,同比提高了T83．89％,效率为14．73％,但其不稳定性对电池效率的影响较为明显。     

联氨对化学水浴沉积ZnS薄膜的影响

在A(ZnSO4、SC(NH2)2、NH4OH)和含有联氨的B(ZnSO4、SC(NH2)2、NH4OH、(NH2)2)两种水溶液中采用化学水浴法沉积ZnS薄膜,研究了联氨对薄膜沉积过程和薄膜性质的影响.结果表明,加入少量联氨以后,薄膜沉积速度明显增加.两种溶液沉积的ZnS都为立方相结构,且含有联氨的B溶液沉积的ZnS薄膜表面附着颗粒较少.在含有联氨的B溶液中沉积的ZnS薄膜结晶度和短波区的透过率均高于A溶液沉积的ZnS薄膜.将两种溶液沉积的ZnS薄膜作为电池缓冲层制备铜铟镓硒(CIGS)薄膜太阳电池,加入联氨沉积的ZnS制备的CIGS电池转换效率达到7.77%,比不加联氨沉积的ZnS制备的CIGS电池转换效率提高了1.3%.     

n-i-p型非晶硅太阳电池中p/ITO界面特性研究

采用射频等离子体增强化学气相沉积(RF-PECVD)技术,制备n-i-p型非晶硅(a-Si)太阳电池,采用反应热蒸发法制备ITO薄膜作为太阳电池的前电极。通过改变B2H6的掺杂浓度获得了不同晶化率的p层,详细研究了p层性能对p/ITO界面特性以及电池性能的影响。结果表明,在合适晶化率的p层上沉积ITO薄膜有利于优化p/ITO界面的接触特性,将其应用于n-i-p型a-Si太阳电池,能够显著改善电池的开路电压(Voc)和填充因子(FF),最终,在不锈钢(SS)衬底上获得了转换效率为6.57%的单结a-Si太阳电池。     

Mn^(2+)掺杂CdS量子点敏化太阳电池的性能北大核心

采用连续式离子层吸附与反应(SILAR)法不仅成功制备出CdS量子点敏化的TiO2纳米晶光阳极,而且实现了Mn2+在CdS量子点晶格内部的可控掺杂。应用场发射扫描电子显微镜(FESEM)对电极的形貌进行了分析和表征。继而通过组装光伏电池研究Mn2+掺杂浓度与电池性能之间的关系。通过测量其紫外-可见吸收光谱及电流密度-电压(J-V)特性曲线考察电池性能随Mn2+掺杂量的变化规律。在研究中发现,掺杂适量的Mn2+有助于提高CdS/TiO2光阳极对可见光的吸收,进而增强太阳电池的能量转换效率。当Mn2+浓度为0.075 mmol/L时,量子点敏化太阳电池(QDSSC)的能量转换效率可达2.85%,较未掺杂的光阳极试样性能提高约50%。     

陷阱分布模型对非晶Si太阳电池性能的影响

利用TCAD软件模拟分析了ITO/p-a-Si:H/i-a-Si:H/n-a-Si:H结构的非晶硅太阳电池的J-V特性,研究了不同缺陷分布模型对太阳电池光电特性的影响。利用一种较精确的陷阱模型优化了太阳电池的结构参数,重点研究了本征层厚度对太阳电池光电特性的影响。模拟实验表明,氢化非晶硅(a-Si:H)PIN结构太阳电池本征层厚度存在一个最佳区间,在该区间电池总体性能较为理想,包括对应的光电转换效率达到峰值。得到的a-Si:H太阳电池填充因子可达到约0.8,最高光电转换效率可达到约13%。     

高效低成本硅太阳电池

SunPower公司发布了高效率低成本硅太阳能电池A -300。A -300以独特的背面接触式设计为基础 ,采用最大化工作单元区和隐藏混乱的连线 ,非常易于实现自动化生产。A -300效率高于20 % ,相比之下 ,现有电池的效率仅为12 %～15 %。该器件经国家可再生能源实验室(NREL)测定 ,其效率达到20.4 %。125mm的单晶硅A -300电池可产生3W电能 ,是光电(PV)业每瓦成本效率最高的解决方案。A -300硅太阳电池在小于17平方米的面积上能提供3kW功率 ,从而使SunPow er的客户能设计出面积利用率最高的建筑方案。A -300太阳电池是屋顶系统、通信、集成了PV…     

Back‐contact solar cells: a review

Ever since the first publications by R.J. Schwartz in 1975, research into back‐contact cells as an alternative to cells with a front and rear contact has remained a research topic. In the last decade, interest in back‐contact cells has been growing and a gradual introduction to industrial applications is emerging. The goal of this review is to present a comprehensive summary of results obtained throughout the years. Back‐contact cells are divided into three main classes: back‐junction (BJ), emitter wrap‐through (EWT) and metallisation wrap‐through (MWT), each introduced as logical descendents from conventional solar cells. This deviation from the chronology of the developments is maintained during the discussion of technological results. In addition to progress on manufacturing these cells, aspects of cell modelling and module manufacturing are discussed and an outlook towards industrial implementation is presented. Copyright © 2005 John Wiley & Sons, Ltd.     

Analysis of the EWT‐DGB solar cell at low and medium concentration and comparison with a PESC architecture

Silicon represents an interesting material to fabricate low‐cost and relatively simple and high‐efficient solar cells in the low and medium concentration range. In this paper, we discuss a novel cell scheme conceived for concentrating photovoltaic, named emitter wrap through with deep grooved base (EWT‐DGB), and compare it with the simpler passivated emitter solar cell. Both cells have been fabricated by means of a complementary metal–oxide–semiconductor‐compatible process in our laboratory. The experimental characterization of both cells is reported in the range 1–200 suns in terms of conversion efficiency, open circuit voltage, short circuit current density and fill factor. In particular, for the EWT‐DGB solar cells, we obtain an encouraging 21.4% maximum conversion efficiency at 44 suns. By using a calibrated finite‐element numerical electro‐optical simulation tool, validated by a comparison with experimental data, we study the potentials of the two architectures for concentrated light conditions considering possible realistic improvements with respect to the fabricated devices. We compare the solar cell figures of merit with those of the state‐of‐the‐art silicon back‐contact back‐junction solar cell holding the conversion efficiency record for concentrator photovoltaic silicon. Simulation results predict a 24.8% efficiency at 50 suns for the EWT‐DGB cell and up to 23.9% at 100 suns for the passivated emitter solar cell, thus confirming the good potential of the proposed architectures for low to medium light concentration. Finally, simulations are exploited to provide additional analysis of the EWT‐DGB scheme under concentrated light. Copyright © 2017 John Wiley & Sons, Ltd.     

A novel strategy for preparing a selective back surface field of n-type emitter wrap through solar cells

In the present study, we have developed a novel mixed co-diffusion (MCD) process by which to prepare a selective back surface field (BSF) of n-type emitter wrap through (EWT) solar cells, which combines a plasma enhanced chemical vapor deposition (PECVD) phosphorus-doped n-type microcrystalline silicon as the dopant source, with a low temperature thermal oxidation (LTO) process. Through comparison between our MCD process and a standard co-diffusion (SCD) process, a BSF with a shallow doping depth of 0.56 µm and high doping concentration of 1.9×10²⁰ at/cm³ is easily obtained by the MCD process under the low temperature of 750 ℃. Therefore, the MCD process is shown to reduce the number of high temperature processes, which cannot produce dopant redistribution, and can accurately control the doping concentrations and depths of the BSF and emitter. In addition, the novel method also eliminates the boron-rich layer, which induces misfit dislocations and bulk lifetime degradation, without extra chemical treatment. Therefore, the MCD process' open circuit voltage, short circuit current density, conversion efficiency and fill factor of the solar cells are respectively increased by 7 mV, 6 mA/cm², 2% and 2%. These results indicate that the MCD process is a novel and potential agent for the SCD process.     

17.9% Metal‐wrap‐through mc‐Si cells resulting in module efficiency of 17.0%

We obtained 17.9% cell efficiency on thin and large mc‐Si REC wafers using ECN's metal‐wrap‐through (MWT) concept. Optimization of several cell processing steps led to an increase of more than 2% absolute in cell efficiency. With these cells 36‐cell modules were manufactured at 100% yield in our industry scale module pilot line. The highest module efficiency obtained (as independently confirmed by JRC‐ESTI) was 17%. In this module the average cell efficiency was 17.8%; this shows a small difference between cell and module efficiency. Copyright © 2011 John Wiley & Sons, Ltd.     

PEDOT:PSS top electrode prepared by transfer lamination using plastic wrap as the transfer medium for organic solar cells

We report on the film preparation of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by transfer lamination using plastic wrap as the transfer medium. Comparing with the commonly used polydimethylsiloxane (PDMS) transfer medium, the plastic wrap is cheaper, easier to access and for mass production. The surface of plastic wrap is less hydrophobic than that of PDMS, aqueous PEDOT:PSS solution with 0.5 wt.% surfactant can wet the plastic wrap well. No plasma or ultraviolet ozone treatment is needed on the plastic wrap prior to the coating of PEDOT:PSS, while plasma treatment is necessary when PDMS is used transfer medium. That simplifies the fabrication process. Organic solar cells with the PEDOT:PSS top electrode transferred using plastic wrap transfer medium exhibit an averaged fill factor of 0.60 and an averaged power conversion efficiency of 4.0%, comparable to that of reference solar cells with PDMS as transfer medium for PEDOT:PSS transfer.     

薄膜太阳电池技术发展趋势浅析

低成本、高效率的薄膜太阳电池是未来光伏产业发展的重要方向之一。主要介绍了目前备受关注的薄膜太阳电池,包括硅基薄膜太阳电池、铜铟镓硒与铜锌锡硫薄膜太阳电池,及砷化镓薄膜太阳电池等,简述了它们的各自特点、研究现状、主要技术路线和产业化发展等情况。最后展望了薄膜太阳电池未来的发展趋势。     

Designing novel thin film polycrystalline solar cells for high efficiency: sandwich CIGS and heterojunction perovskite

Heterojunction and sandwich architectures are two new-type structures with great potential for solar cells. Specifically, the heterojunction structure possesses the advantages of efficient charge separation but suffers from band offset and large interface recombination; the sandwich configuration is favorable for transferring carriers but requires complex fabrication process. Here, we have designed two thin-film polycrystalline solar cells with novel structures:sandwich CIGS and heterojunction perovskite, referring to the advantages of the architectures of sandwich perovskite (standard) and heterojunction CIGS (standard) solar cells, respectively. A reliable simulation software wxAMPS is used to investigate their inherent characteristics with variation of the thickness and doping density of absorber layer. The results reveal that sandwich CIGS solar cell is able to exhibit an optimized efficiency of 20.7%, which is much higher than the standard heterojunction CIGS structure (18.48%). The heterojunction perovskite solar cell can be more efficient employing thick and doped perovskite films (16.9%) than these typically utilizing thin and weak-doping/intrinsic perovskite films (9.6%). This concept of structure modulation proves to be useful and can be applicable for other solar cells.     

Circuit modeling of the emitter-wrap-through solar cell

Back-contact solar cells have the potential to reduce module assembly costs and give a higher conversion efficiency. Such a device must be simple to fabricate on an industrial scale and be tolerant of low minority-carrier diffusion lengths. The emitter-wrap-through (EWT) cell is a device design that can meet these goals. In this device, the diffused junction is present on both sides and is connected by laser-drilled holes through the silicon. EWT cells were frequently found to have poor fill factors (FFs) due to shunt-like behavior. The holes were found to possess no defects that adversely affect device performance. However, detailed equivalent circuit modeling of the EWT cell was able to explain the shunt-like behavior. Experiments were performed to confirm the physical mechanisms described by the equivalent circuit model. Device optimization guided by the equivalent circuit model has led to the demonstration of a large area EWT cell with a FF of 77.64% and efficiency of 18.2%     

锗掺杂磁控直拉单晶硅太阳电池

介绍了锗掺杂浓度为（1～1.5) E19cm-3的10Ω·cm磁控直拉单晶硅衬底上BSFR (back surface field and reflection）和BSR(back surface reflection)太阳电池的制备和电性能. BSR锗掺杂单晶硅太阳电池的AM0效率最高为12.3%. BSFR锗掺杂单晶硅太阳电池的AM0效率达到15%. 利用1MeV的高能电子对制备的锗掺杂单晶硅太阳电池进行了辐照实验. 作为对比，对全部常规10Ω·cm的CZ单晶硅太阳电池也进行了实验. 结果表明，锗掺杂浓度为（1～1.5)E19cm-3的磁控直拉单晶硅太阳电池的电性能和抗辐照性能与常规直拉硅太阳电池基本相同. 利用锗掺杂磁控直拉单晶硅片机械强度较高的优点，可以降低太阳电池生产过程破损率.