酸性添加剂对多晶硅绒面形貌的影响

采用各向同性腐蚀法制备多晶硅绒面,通常使用的腐蚀液为HNO3和HF的混合溶液,增加适量酸性添加剂,可以有效地改进制绒效果,提高多晶硅电池转换效率。文章研究了酸性添加剂在不同酸腐蚀液浓度配比条件下制备的绒面特性。研究结果表明,腐蚀液中加入酸性添加剂后,绒面表面腐蚀坑细小均匀,有效地降低了绒面反射率,减少了电池产生的漏电;当腐蚀液中HNO3/HF/酸性添加剂的浓度比为8∶1∶0.4时,所制备绒面的反射率达到最低值,为21.87%,其转换效率最高。     

硅片表面织构对PERC单晶硅太阳电池电性能影响的研究

通过调整制绒腐蚀液添加剂中表面活性剂和成核剂的添加比例,制备出不同表面织构的硅片,研究了表面活性剂和成核剂的添加比例对硅片表面微观形貌和反射率,以及PERC单晶硅太阳电池电性能的影响规律。结果表明：随着表面活性剂添加比例的增加,腐蚀液对硅片的清洗效果逐渐增强,存在黑斑、麻点及脏污的太阳电池的占比逐渐减少;同时,单晶硅片表面形成的金字塔尺寸(宽度)逐渐减小,比表面积先增大后减小,从而导致太阳电池的光电转换效率呈现先升高再降低的规律;当表面活性剂的添加比例为0.6%时,太阳电池的光电转换效率达到最大值,为22.736%。随着成核剂添加比例的增加,单晶硅片绒面金字塔的均匀性逐渐提升,当成核剂的添加比例大于0.8%时,绒面金字塔的均匀性基本稳定,太阳电池的光电转换效率也达到最大值,为22.784%。     

单晶硅电池碱腐蚀制绒工艺的试验研究

介绍了单晶硅电池碱腐蚀制绒技术和金字塔结构形成的原理,通过NaOH碱性溶液浓度、异丙醇浓度、制绒腐蚀时间、制绒腐蚀温度、硅酸钠含量等优化试验,制备出具有不同金字塔状绒面的太阳能电池。采用扫描电子显微镜观察样品的表面形貌,并进行了分析讨论。通过对影响金字塔状绒面性能质量的关键因素研究,得出了碱腐蚀制绒的最佳工艺参数:NaOH浓度为15 g/L;异丙醇体积浓度为3%～10%;反应时间为30 min;反应温度为85℃;Na2Si03.9H2O质量含量为5%;样品绒面平均反射率为9.1%。     

背面结构对铝背发射极n型单晶硅太阳电池的影响研究

研究背面结构对铝背发射极n型单晶硅太阳电池的影响,提出背面抛光结构铝背发射极n型单晶硅太阳电池的制备方法。使用少子寿命测试仪、扫描电镜(SEM)、量子效率测试仪及太阳电池测试仪对电池的表面复合速率、微观结构、量子效率和电性能进行测定。结果表明:对铝背发射极n型单晶硅太阳电池,背面抛光结构优于背面金字塔绒面结构,背面抛光结构可降低电池背面的复合速率、改善p-n结质量、提高量子效率,使电池转换效率提高0.34%。     

银硅纳米颗粒用于制备晶体硅太阳电池超高效陷光的研究

研究了制备硅纳米结构的方法,与之前的方法相比,本研究中的AgSi纳米颗粒能控制形成硅纳米结构的直径和深度,同时不需要光刻、反应离子刻蚀等高成本的复杂工艺.实验结果表明,将制备的硅纳米结构作为晶硅电池的绒面,在300～ 1000nm的波长范围内获得了低达5％的反射率;电池的表面复合与电极接触需要改进.     

化学腐蚀法制备多晶硅的绒面

为了降低光在多晶硅表面的反射,采用化学腐蚀法在其表面制备了绒面。根据反射光谱的测试结果,研究了不同多晶硅绒面的形貌特征及光学特性。在适当的腐蚀液中制备了3×3cm2、5×5cm2和10×10cm2多晶硅绒面。10×10cm2多晶硅绒面,在300～1100nm波长范围内的加权反射率的最好结果为5 2%,表面织构均匀,这一结果可以和具有双层减反射膜的多晶硅表面的反射率相比拟。     

串联电阻对不均匀铜铟镓硒电池性能的影响

由于铜铟镓硒太阳电池的不均匀性以及电池输出特性的非线性,现有表征大面积电池的加权平均效率需要进行修正以便更好反映光伏组件的效率。由于串联电阻的增加常被认为可改善电池均匀性,因此本文针对串联电阻的影响进行重点研究。本文基于太阳电池模型,假定大面积太阳电池可看作是多个小面积太阳电池单元并联而成的太阳电池单元组件。计算结果表明,并联光伏组件的效率比加权平均效率低;提高光伏组件的串联电阻能在一定程度上改善电池不均匀性,但未必能提高光电转换效率,这有赖于光伏组件的不均匀程度和其本身的串联电阻大小;当光伏组件本身的均匀性较好且串联电阻也较小时,提高光伏组件的串联电阻能提高光伏组件效率。     

分频型光伏光热系统中丙二醇基Ag/CoSO_4纳米流体的性能研究

为进一步提升光伏光热(PV/T)系统性能,采用丙二醇基Ag/CoSO_4纳米流体作为PV/T系统的光谱分频液。利用分光光度计表征不同浓度分频液的光学性能,并通过实验研究其对聚光硅太阳电池电性能的影响,最后理论分析PV/T系统的综合性能。结果表明:丙二醇基Ag/CoSO_4纳米流体中CoSO_4和银纳米颗粒具有光学协同效应;在该分频液下电池电性能下降,而PV/T系统的总效率有显著提升;并随纳米流体浓度的增加,总效率不断增大,但系统MF值却先增后减;在所制备的4种浓度中,银纳米颗粒质量分数为3.18×10-3%时具有最大MF值,为1.37。     

Ag催化化学腐蚀多晶绒面的制备及其特性研究

该文采用液相两步法成功制备出具有高质量性能的黑硅绒面。当Ag粒子沉积时间为10 s、AgNO_3浓度为0.01 mol/L,H_2O_2浓度为0.9%,黑硅刻蚀时间为120 s时,硅片绒面反射率最小为5.47%;Ag粒子去除阶段,采用碱洗方式去除残余银颗粒的效果要优于酸洗;黑硅纳米绒面重塑阶段,时间控制在90 s时纳米锥大小一致、均匀度最优。     

超薄柔性黑硅太阳电池研究

通过PC1D模拟软件分析了硅片厚度对电池性能的影响,结果表明:随着硅片厚度减薄,硅片对光的吸收效率逐渐减弱。为了强化硅片表面的陷光能力,弥补硅衬底减薄对光吸收的损失,采用化学刻蚀法制备获得了具有纳米绒面的黑硅太阳电池。通过模拟对比厚度为80μm的黑硅电池和常规电池性能,结果表明:硅纳米长度为0.85μm的黑硅表面平均反射率从常规制绒的12.65%降低至4.06%,黑硅电池短路电流从常规的8.693 A增加至9.104 A,黑硅电池效率从常规的18.87%提高至19.74%。     

多晶PERC太阳电池的背面与正面结构性能优化

多晶硅太阳电池以其价格低廉的优势成为低成本太阳电池的首选,但其光电转换效率提升空间有限。钝化发射极和背面电池（PERC）技术是当前晶硅太阳电池提效的主要途径。多晶PERC电池结合了多晶硅电池的低成本和PERC电池的高效,是当前多晶硅电池的研究热点。本文研究了多晶PERC电池的背面和正面结构优化与设计,提出了提高多晶PERC电池效率的产业化技术方法。通过在硅片背面用三层SiN_x:H薄膜来代替常规双层SiN_x:H薄膜,在保证优良的背面钝化的同时,使电池长波响应得到改善,电池光电转换效率由20.19% 提升至20.26%。优化多晶PERC电池的背面激光开窗工艺,使多晶电池效率较常规工艺提升0.11%。而在多晶PERC电池的正面叠加选择性发射极技术,可较常规工艺提升电池效率0.10%。综合运用多种提效手段有利于保持多晶PERC电池的竞争力。     

Surface plasmon enhanced GaAs thin film solar cells

As a new method to improve the light trapping in solar cells, surface plasmon resonance (SPR) has attracted considerable attention because of its unique characteristics. Several studies have been reported on the photocurrent improvement of Si solar cells by surface plasmons, while little research has been done on III-V solar cells. In this work, we performed a systematic study of SPR on GaAs thin film solar cells with different sizes of Ag nanoparticles on the surface. The nanoparticles were fabricated by annealing E-beam evaporated Ag films in a N₂ atmosphere. It was found that the surface plasmon resonance wavelength does not undergo a simple red-shift with increasing metal thickness. It depends on the shape of the metal nanoparticles and the interparticle spacing. It is necessary to optimize the particle size to obtain an optimum enhancement throughout the visible spectrum for solar cells. We found that the optimum thickness of the Ag film was 6 nm under our experimental conditions. Furthermore, from the calculation based on the external quantum efficiency data, the short circuit current density of a GaAs solar cell with 6 nm Ag film after annealing was increased by 14.2% over that of the untreated solar cell.     

Cost effective process for high-efficiency solar cells

A new method for patterning the rear passivation layers of high-efficiency solar cells with a mechanical scriber has been developed and successfully adapted to fabricate high-efficiency passivated emitter and rear cell (PERC). Three types of the rear contact patterns: dot patterns with a photolithography process, line and dashed line patterns with a mechanical scriber process have been processed in order to optimize the rear contact structure. An efficiency of 19.42% has been achieved on the mechanical-scribed (MS)-PERC solar cell on 0.5 Ω cm p-type FZ-Si wafer and is comparable to that of conventional PERC solar cells fabricated by using photolithography process. The mechanical scriber process shows great potential for commercial applications by achieving high efficiency above 20% and by significantly reducing the fabrication costs without an expensive photolithography process. Low-cost Ni/Cu metal contact has been formed by using a low-cost electroless and electroplating. Nickel silicide formation at the interface enhances stability and reduces the contact resistance resulting in an energy conversion efficiency of 20.2% on 0.5 Ω cm FZ wafer.     

烧结曲线对多晶PERC太阳电池光致衰减效应的影响

针对多晶PERC太阳电池其较大的光衰效应会影响功率输出的问题,研究烧结曲线对多晶PERC太阳电池光致衰减效应的影响。在常规烧结曲线1的基础上通过改变烧结曲线峰值温度位置得到优化烧结曲线2和优化烧结曲线3,然后将双面沉积Al2O3/SiNx叠层钝化膜的寿命片和丝网印刷后的多晶PERC电池分别采用不同烧结曲线热处理,最后将样品在70℃、800 W/m2环境下进行45 h光衰处理。结果发现经过烧结曲线1~曲线3处理后的寿命片少子寿命衰减率分别为63%、42%和23%,多晶PERC太阳电池转换效率的衰减率分别为6.46%、3.55%和2.30%,光衰处理后的多晶PERC电池的EL测试结果显示烧结曲线1亮度最小,曲线2次之,曲线3最大。以上结果表明,仅通过烧结炉的烧结曲线优化就可以很明显地减小多晶PERC太阳电池的光致衰减幅度,可为探究抑制多晶PERC太阳电池光致衰减效应的方法提供一种全新的思路。     

不同背反射结构在硅异质结太阳电池中的应用研究

该文旨在利用银纳米颗粒（Ag NPs）和SiO_x/Ag背反射结构提升硅异质结（SHJ）太阳电池在900~1200nm波段红外光谱响应。研究在SHJ太阳电池背光侧分别制备Ag、SiO_x/Ag和嵌入Ag NPs的SiO_x/Ag几种背反射结构,以最大限度提升SHJ太阳电池红外光谱响应。结果表明：SiO_x/Ag背反射结构可有效减少红外光的逃逸损失,提升太阳电池红外光谱响应,使得双面制绒SHJ太阳电池短路电流密度从37.74 mA/cm²提升到38.07 mA/cm²;但嵌入Ag NPs并不能帮助SiO_x/Ag背反射结构进一步提升双面制绒SHJ电池红外光谱响应,证明了基于其局域表面等离激元共振效应仅对陷光能力较差的平面太阳SHJ电池有一定提升。     

Application of phosphorus diffusion gettering process on upgraded metallurgical grade Si wafers and solar cells

Although phosphorus (P) diffusion gettering process has been wildly used to improve the performance of Si solar cells in photovoltaic technology, it is a new attempt to apply P diffusion gettering process to upgraded metallurgical grade silicon (UMG-Si) wafers with the purity of 99.999%. In this paper, improvements on the electrical properties of UMG-Si wafers and solar cells were investigated with the application of P diffusion gettering process. To enhance the improvements, the gettering parameters were optimized on the aspects of gettering temperature, gettering duration and POCl₃ flow rate, respectively. As we expected, the electrical properties of both multicrystalline Si (multi-Si) and monocrystalline Si (mono-Si) wafers were significantly improved. The average minority carrier lifetime increased from 0.35 μs to nearly about 2.7 μs for multi-Si wafers and from 4.21 μs to 5.75 μs for mono-Si wafers, respectively. Accordingly, the average conversion efficiency of the UMG-Si solar cells increased from 5.69% to 7.03% for multi-Si solar cells (without surface texturization) and from 13.55% to 14.55% for mono-Si solar cells, respectively. The impurity concentrations of as-grown and P-gettered UMG-Si wafers were determined quantitively so that the mechanism of P diffusion gettering process on UMG-Si wafers and solar cells could be further understood. The results show that application of P diffusion gettering process has a great potential to improve the electrical properties of UMG-Si wafers and thus the conversion efficiencies of UMG-Si solar cells.     

整形激光掺杂制备PERC电池选择性发射极研究

研究整形激光掺杂制备选择性发射极(SE)对p型单晶硅钝化发射极局域背接触(PERC)太阳电池的表面金字塔形貌、掺杂分布及电池性能的影响。整形激光具有能量分布均匀、对硅片损伤小等优点。通过改变激光的功率以及激光划线速度在p型单晶硅PERC太阳电池制备了不同掺杂分布的发射极。结合3D激光显微镜、扫描电子显微镜、EDS能谱分析、四探针方阻测试仪、电化学电容法等测试分析方法表征了样品的表面形貌、方阻变化、掺杂浓度曲线和电学性能。本文结合光斑重叠率将不同激光功率和激光划线速度采用公式统一转化为激光能量密度,从而得出制备选择性发射极的最佳激光能量密度。研究结果表明,当激光能量密度为0.97 J/cm2时,电池效率可以稳定提升0.25%以上,体现了整形激光SE技术应用于PERC电池的应用潜力。     

Large-size multi-crystalline silicon solar cells with honeycomb textured surface and point-contacted rear toward industrial production

In this paper, we present a multi-crystalline solar cell with hexagonally aligned hemispherical concaves, which is known as honeycomb textured structure, for an anti-reflecting structure. The emitter and the rear surface were passivated by silicon nitride, which is known as passivated emitter and rear (PERC) structure. The texture was fabricated by laser-patterning of silicon nitride film on a wafer and wet chemical etching of the wafer beneath the silicon nitride film through the patterned holes. This process succeeded in substituting the lithographic process usually used for fabricating honeycomb textured structure in small area. After the texturing process, solar cells were fabricated by utilizing conventional fabrication techniques, i.e. phosphorus diffusion in tube furnace, deposition of anti-reflection film and rear passivation film by chemical vapor deposition, front and rear electrodes formation by screen printing, and contact formation by furnace. By adding relatively small complicating process to conventional production process, conversion efficiency of 19.1% was achieved with mc-Si solar cells of over 200 cm² in size. The efficiency was independently confirmed by National Institute of Advanced Industrial Science and Technology (AIST).     

MoOx/Ag/MoOx multilayers as hole transport transparent conductive electrodes for n-type crystalline silicon solar cells

Substitution of highly doped layers with conventional transparent conductive electrodes as carrier collecting and selective contacts in conventional crystalline silicon (c-Si) solar cell configurations is crucial in increasing affordability of solar cells by lowering material costs. In this study, oxide/metal/oxide (OMO) multilayers featuring molybdenum oxide (MoO_x) and silver (Ag) thin films are developed by thermal evaporation technique, as dopant-free hole transport transparent conductive electrodes (HTTCEs) for n-type c-Si solar cells. Semidopant-free asymmetric heterocontact (semi-DASH) solar cells on n-type c-Si utilizing OMO multilayers are fabricated. The effect of outer MoO_x layer thickness and Ag deposition rate on the photovoltaic characteristics of the fabricated semi-DASH solar cells are investigated. A comparison of front side pyramid textured and flat surface solar cells is performed to optimize the optical and electrical properties. Highest efficiency of 9.3% ± 0.2% is achieved in a pyramid textured semi-DASH c-Si solar cell with 15/10/30 nm of HTTCE structure.     

Reactive ion etching (RIE) technique for application in crystalline silicon solar cells

Saw damage removal (SDR) and texturing by conventional wet chemical processes with alkali solution etch about 20 micron of silicon wafer on both sides, resulting in thin wafers with which solar cell processing is difficult. Reactive ion etching (RIE) for silicon surface texturing is very effective in reducing surface reflectance of thin crystalline silicon wafers by trapping the light of longer wavelength. High efficiency solar cells were fabricated during this study using optimized RIE. Saw damage removal (SDR) with acidic mixture followed by RIE-texturing showed the decrease in silicon loss by ∼67% and ∼70% compared to conventional SDR and texturing by alkaline solution. Also, the crystalline silicon solar cells fabricated by using RIE-texturing showed conversion efficiency as high as 16.7% and 16.1% compared with 16.2%, which was obtained in the case of the cell fabricated with SDR and texturing with NaOH solution.