银粉对硅太阳电池正银电极性能的影响

利用不同性能的银粉配制正银浆料,通过丝网印刷、烧结工艺制作硅太阳电池,研究银粉粒径、形貌和结晶性等对硅太阳电池正银的丝网印刷性能和电池转换效率等性能的影响。用扫描电镜(SEM)分析正银栅线电极的微观结构及烧结后Ag-Si界面处银微晶的形成情况。结果表明,银粉粒径和形貌对栅线电极的高-宽比和电极致密性有直接影响;Ag-Si界面处的银微晶大小和数量是正银电极形成欧姆接触的关键。利用正银电极的烧结原理,分析不同银粉对正银电极欧姆接触形成的影响,粒径为1.47μm的球形银粉,有较高的振实密度和烧结活性,制备的电池转换效率较高。     

银浆组成对硅太阳电池丝网印刷欧姆接触的影响

通过作图的传输线法测定比接触电阻率,定量地研究硅太阳电池正面电极用银导电浆料中银粉颗粒大小和玻璃相组成对银电极/硅表面欧姆接触的影响.结果表明,随着银导电浆料中银粉颗粒尺寸的增大比接触电阻下降,形成较好的欧姆接触;当玻璃相中铅含量增加时,在一定的烧结温度下,比接触电阻率减小.     

晶体硅太阳电池接触电阻测量方法

分析传输线模型(TLM)法在接触电阻测量中的缺陷,通过建立金属-半导体界面的电压、电流方程推导出不同电流模式下接触电阻的表达式,在TLM法的基础上提出新的测量方法,可精确测量电极与硅体的比接触电阻率和接触界面的薄层方块电阻,从而准确计算出太阳电池接触电阻。该方法测量方便、计算结果精确,可有效应用于晶体硅太阳电池接触电阻的研究。     

从Ⅰ-Ⅴ特性曲线分析太阳电池烧结工艺条件

通过对太阳电池的I-V特性曲线进行检测分析,得出太阳电池的串、并联电阻与电极烧结的各个温度段的温度密切相关,并联电阻受高温区温度和烧结时间(带速)的影响。通过对烧结工艺的优化调整,获得了较好性能的太阳电池,得到了烧结工艺调整优化的方法。     

银粉对硅异质结太阳电池用低温银浆的影响综述

银浆是硅异质结太阳电池的重要材料,更低的体积电阻率和接触电阻、良好的附着力、优良的细线印刷性能及组件栅线抗腐蚀老化是其不断改进的方向。作为导电相,银粉的性能和含量对银浆有着至关重要的影响。该文基于低温固化银浆导电机理以及SHJ电池对银浆性能的追求,综述了银粉的振实密度、形貌、粒径、表面处理剂及其与有机物的适配。进一步探讨了纳米银粉和银包铜粉在SHJ太阳电池用低温银浆中的应用。     

铝粉活性对双面PERC太阳电池铝浆性能的影响

探究了铝粉活性对铝浆电阻及双面PERC太阳电池开路电压的影响.实验结果表明:高活性的铝粉制备的铝浆具有较低的方阻、接触电阻及线电阻,且铝硅接触电阻率可低至11.5 mΩ?cm2;一定范围内,活性较低的铝粉制备的铝浆具有较高的开路电压,开路电压可达690.774 mV.根据太阳电池的尺寸、钝化膜质量、背面激光开槽面积、主...     

金属硅化物接触太阳电池

本文报道了硅太阳电池镍硅化物-硅接触形成的条件及对太阳电池特性的影响。     

产业化晶硅太阳电池串联电阻研究

详细研究了产业化晶硅太阳电池生产中,电池正面电极体电阻、发射极横向电阻,以及正面电极与发射极结区金/半接触电阻对晶硅太阳电池串联电阻的具体影响。通过实验,文章给出了一种既经济又能有效降低电池串联电阻、提升晶硅太阳电池光电转换效率的优化方法。     

用于丝网印刷的掺杂硅浆料

利用等离子体气相合成法制备硅纳米颗粒,配制出基于硅纳米颗粒的用于丝网印刷的掺杂硅浆料。当硅浆料中磷硅原子比不小于0.45、磷的质量分数浓度在6.32%以上,或硼硅原子比不小于0.90、硼的质量分数浓度在1.75%以上时,用丝网印刷硅浆料能够实现方块电阻在50Ω/□以下的重掺效果,表明掺杂硅浆料有望应用于太阳电池的制备。     

简讯

西安交通大学和华山半导体材料厂共同研制成适合于地面应用的直径75毫米丝网印刷绒面硅太阳电池。这种电池由于采用了绒面结构、化学镀镍、丝网印刷等工艺,避免了真空镀膜技术所遇到的限制;由于采用了烧结技术,解决了镍电极的牢固度问题。新工艺     

Physical understanding of the behavior of silver thick-film contacts on n-type silicon under annealing conditions

High-efficiency silicon solar cells with evaporated front contacts and an oxide-passivated rear require post metallization annealing (PMA). In an industrial environment the evaporated front contacts are replaced by screen printed contacts for fast processing and cost reasons. The PMA conditions necessary for optimum rear side passivation can be inferior to such a front side metallization. In order to design a PMA supporting contact in future, this paper investigates what mechanism deteriorates the contact resistance of screen printed front side metallization during nitrogen PMA. Scanning electron microscopy (SEM) on samples with increased contact resistance reveals an altered microstructure at the silver-silicon contact interface that is proposed to impede current flow and hence increases the contact resistance. We present a model that describes the mechanism of contact deterioration during nitrogen PMA.     

A study of shading and resistive loss from the fingers of encapsulated solar cells

Optimised solar cell design is dependent on the assumed shading and resistance losses associated with front contacts. In this study, a spectrophotometer with integrating sphere attachment was used to measure the reflection from the front surface of encapsulated silver electroplated front contact solar cells. The results obtained are in good agreement with a previous study by one of the authors using a different method. The measured effective shading loss is about one third of the coverage fraction of the cell grid because of trapping of light reflected from the grid. The grid loss in 4×5 cm silver electroplated front contact solar cells was found to be similar to the predicted loss from buried grid and rear point contact solar cells operating at 30 suns concentration.     

Error diagnosis and optimisation of c-Si solar cell processing using contact resistances determined with the Corescanner

The screen-printing metallisation process used for 90% of industrially produced solar cells is sensitive to process conditions. The best way to monitor this contacting process is to measure contact resistance. The standard technique used is the transmission line method. However, this only measures contact resistance locally.In this paper, contact resistance over the whole cell surface is measured with the newly developed ‘Corescanner’. Using this instrument, the relation between processing parameters and solar cell contact resistance distribution is investigated. Our most important finding is that poor contacting results in large inhomogeneities in contact resistance. Even for cells with very low fill factors, regions of low contact resistance can be found.To conclude, the Corescanner provides us with a technique to monitor contact resistance. This instrument is an invaluable tool for fault detection, error diagnosis and process optimisation.     

Bulk and contact resistance in P3HT:PCBM heterojunction solar cells

In this paper, the series resistance of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) bulk heterojunction (BHJ) organic solar cells (OSC) has been studied. The series resistance of thermal annealed and un-annealed devices with different active layer thicknesses was measured. The series resistance of the organic solar cells consists of the bulk resistance of the active layer itself and the specific contact resistance between the active layer and the electrode. The bulk resistance and contact resistance were extracted from the measured series resistance using the vertical transmission line model (TLM) method. By fabricating solar cell devices with different active layer thicknesses, a relationship of the series resistance with thickness was established from which bulk and contact resistances were derived. We have also found that thermal annealing helps reduce both contact resistance and bulk resistance significantly; the contact resistance dropped by a factor of 2, while the bulk resistance decreased by a factor of 8. Results have shown that for an annealed P3HT:PCBM device that has an active layer thickness of 85 nm (optimum thickness for high efficiency), 17% of the total series resistance was due to the contact resistance, and bulk resistance contributed the rest 83%. The bulk resistance value for thermal annealed organic solar cell device with an active area of 0.1 cm² was found to be 150 Ω, and the measured specific contact resistance was 3.1 Ω cm². The measured bulk and contact resistance values are much higher as compared to the high efficiency silicon solar cells. Bulk resistance and contact resistance need to be further decreased in order to achieve higher organic solar cell efficiency.     

Fabrication of buried contact silicon solar cells using porous silicon

We report the fabrication of buried contact solar cells using porous silicon as sacrificial layer to create well-defined channels (for buried contacts) in silicon. In this paper, the salient features of the technology have been presented. No detrimental effect was found in the performance of buried contact solar cell with partially filled contact area compared to the solar cells having conventional planar contacts. However, a marked difference in the short circuit current density was seen when channel was fully filled with metal by screen printing, without degradation in the open-circuit voltage. It is expected that improved processing in combination with optimized buried metallic contact parameters may yield higher efficiencies that may result in substantial decrease in solar cell cost.     

A new technique for large-area thin film CdS/CdTe solar cells

The atmospheric pressure CSS method has been developed as a reproducible and efficient process. Thin film CdTe grown under atmospheric pressure has a rough surface morphology. The density of carbon black powder in the graphite carbon paste for screen printing is a key factor in reducing the series resistance of the device with rough surface CdTe. Using graphite carbon paste with 7 wt% carbon black powder has resulted in cells with a relatively low back contact resistance. A highly efficient large-area CdS/CdTe solar cell (11.0%, 5327 cm²) sub-module has been fabricated using the new technique.     

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。     

Lateral current effects on the voltage distribution in the emitter of solar cells under concentrated sunlight

The design of the grid contact in silicon solar cells is one of the most important steps for the optimization and fabrication of these energy conversion devices. The voltage drop due to the lateral flow of current towards the grid fingers can be a limiting factor causing the reduction of conversion efficiency. For low current levels this voltage drop can be made small, for typical values of sheet resistance in the emitter, but for solar cells made to operate at high sun concentrations this efficiency loss can be important, unless there is a clear vision of the current and voltage distribution so that the emitter and grid design can be improved. Hence, it is important to establish and solve the current and voltage distribution equations for solar cells with a grid contact. In this work, first these equations are established and then they are solved in order to show the effects that the lateral current flow in the emitter cause on the voltage distribution, particularly at high illumination levels. In addition, it will be shown that the open circuit voltage is significantly reduced due to the lateral current flow as compared to the value predicted from a simple equivalent circuit with a lumped resistance model.     

Planar rear emitter back contact silicon heterojunction solar cells

A planar rear emitter back contact silicon heterojunction (PreBC-SHJ) solar cell design is presented, which combines the advantages of different high efficiency concepts using point contacts, back contacts, and silicon heterojunctions. Electrically insulated point or stripe contacts to the solar cell absorber are embedded within a planar hydrogenated amorphous silicon emitter layer deposited at low temperature on the rear side. The new solar cell design requires less structuring and allows large structure sizes, enabling the use of low-cost patterning technologies such as inkjet printing or screen printing. By means of numerical computer simulation the efficiency potential of back contacted heterojunction solar cells is shown to exceed 24%. First PreBC-SHJ solar cells have been realized and exhibit higher short circuit currents than our state-of-the-art front contacted silicon heterojunction reference solar cells.     

SCREEN PRINTED AND SINTERED CdTe-CdS SOLAR CELLS

Screen printed and sintered CdTe-CdS solar cells differ in some aspects from other CdTe cells: the layers are thicker, the fabrication temperatures higher, the grain size is usually better. A good morphology, a good junction behaviour and consequently a high open circuit voltage, and efficient doping of the CdTe are seen to be an inherent advantage of the screen printing and sintering technology. On the other hand, care has to be taken to avoid strong interdiffusion and optical transmission loss in the CdS window.