Investigation on Silicon Thin Film Solar Cells

The preparation,current status and trends are investigated for silicon thin film solar cells.The advantages and disadvantages of amorphous silicon thin film,polycrystalline silicon thin film and mono-crystalline silicon thin film cells are compared.The future development trends are pointed out.It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.     

Ag纳米粒子等离子体共振增强太阳能电池吸收

针对薄膜太阳能电池硅薄膜层吸收效率较低的问题,提出了运用金属纳米粒子局域表面等离子体共振(LSPR)增强太阳能电池的吸收效率,采用时域有限差分(FDTD)法,模拟计算了太阳能电池中不同厚度的硅薄膜层吸收特性,分析了不同几何参数的矩形Ag纳米粒子与Ag背反射膜对增强太阳能电池吸收效率的影响作用。计算结果表明,硅薄膜层厚度为500nm的太阳能电池具有较高的吸收效率,通过调整Ag纳米粒子的相关参数,有效地降低了太阳电池硅薄膜表面的反射损耗,取得最大吸收增强因子为1.35。Ag背反射膜有效地降低了Ag纳米粒子硅薄膜结构的透射损耗,其最大的吸收增强因子达到1.42。     

Sunrise to sunset optimization of thin film antireflective coatings for encapsulated,planar silicon solar cells

We present an approach for the optimization of thin film antireflective coatings for encapsulated planar silicon solar cells in which the variations in the incident spectra and angle of incidence (AOI) over a typical day are fully considered. Both the angular and wavelength dependences of the reflectance from the surface, absorptance within the coating, and transmittance into the device are calculated for both single‐ and double‐layer antireflection coatings with and without thin silicon oxide passivation layers. These data are then combined with spectral data as a function of time of day and internal quantum efficiency to estimate the average short‐circuit current produced by a fixed solar cell during a day. This is then used as a figure of merit for the optimization of antireflective layer thicknesses for modules placed horizontally at the equator and on a roof in the UK. Our results indicate that only modest gains in average short‐circuit current could be obtained by optimizing structures for sunrise to sunset irradiance rather than AM1·5 at normal incidence, and fabrication tolerances and uniformities are likely to be more significant. However, we believe that this overall approach to optimization will be of increasing significance for new, potentially asymmetric, antireflection schemes such as those based on subwavelength texturing or other photonic or plasmonic technologies currently under development especially when considered in combination with modules fixed at locations and directions that result in asymmetric spectral conditions. Copyright © 2009 John Wiley & Sons, Ltd.     

Use of tin oxide as an inexpensive antireflection coating for p on n polycrystalline silicon solar cells

The potential of tin oxide as an inexpensive antireflection (AR) coating for polycrystalline silicon solar cells has been investigated. Undoped tin oxide films of a desired thickness were deposited over p on n polycrystalline silicon solar cells by spray pyrolysis of an alcoholic solution of hydrated stannic chloride at 500°C. Evaluation of cell performance before and after this AR coating showed that the AR coating is highly compatible with the polycrystalline silicon solar cells. About 40-50 percent improvement in the short-circuit current of p on n polycrystalline cells has been measured. The coating may be highly suited to large-scale production of low-cost polycrystalline silicon solar cells for terrestrial application.     

Perspectives of crystalline Si thin film solar cells: a new era of thin monocrystalline Si films?

A large number of competing approaches are currently being investigated around the world to develop crystalline silicon thin film solar cells on foreign substrates. These approaches can be broadly classified according to the crystalline state of the Si films employed: (i) thin film solar cells based on nano‐ or microcrystalline Si‐films; (ii) cells fabricated from large‐grained polycrystalline Si and (iii) recent approaches utilizing the transfer of monocrystalline Si films. The paper discusses prospects and limitations of these approaches and describes device results based on the transfer of quasi‐monocrystalline Si films. Using Si absorber films epitaxially grown on quasi‐monocrystalline Si, we achieve a conversion efficiency of 13˙6% for a 4 cm² sized thin film solar cell on glass. In contrast to the limited performance of polycrystalline Si thin film solar cells imposed by the presence of grain boundaries, transfer approaches are expected to result in thin film solar cell efficiencies in the range of 15 – 18% depending on process maturity and complexity. The transfer of monocrystalline Si films therefore opens a new avenue to an efficient and competitive Si‐based thin film technology. Copyright © 2000 John Wiley & Sons, Ltd     

废弃多晶硅太阳电池回收高纯硅片工艺研究

论述分析了国内外晶体硅太阳电池回收技术现状,研究了太阳电池的结构及制备工艺,提出了废弃多晶硅太阳电池回收高纯硅片的工艺.依次去除铝背场/铝硅合金层/背银、氮化硅减反膜/正银、磷扩散层及金属杂质,得到高纯硅片.硅原料的回收率高达76.4％,回收的高纯硅片经检验检测,其电阻率、间隙氧浓度、代位碳含量和少子寿命均符合GB/T 29055-2012中规定的性能参数.该回收工艺路线简单,回收率高,成本低,适于产业化推广.废弃太阳电池的回收再利用不仅可以在一定程度上缓解硅原料短缺的问题,还可以减少废弃的太阳电池给环境造成负担.     

High efficiency polycrystalline silicon solar cells using lowtemperature PECVD process

Conventionally directionally solidified (DS) and silicon film (SF) polycrystalline silicon solar cells are fabricated using gettering and low temperature plasma enhanced chemical vapor deposition (PECVD) passivation. Thin layer (~10 nm) of PECVD SiO₂ is used to passivate the emitter of the solar cell, while direct hydrogen rf plasma and PECVD silicon nitride (Si₃N₄) are implemented to provide emitter and bulk passivation. It is found in this work that hydrogen rf plasma can significantly improve the solar cell blue and long wavelength responses when it is performed through a thin layer of PECVD Si₃N₄. High efficiency DS and SF polycrystalline silicon solar cells have been achieved using a simple solar cell process with uniform emitter, Al/POCl₃ gettering, hydrogen rf plasma/PECVD Si₃N₄ and PECVD SiO₂ passivation. On the other hand, a comprehensive experimental study of the characteristics of the PECVD Si₃N₄ layer and its role in improving the efficiency of polycrystalline silicon solar cells is carried out in this paper. For the polycrystalline silicon used in this investigation, it is found that the PECVD Si₃N₄ layer doesn't provide a sufficient cap for the out diffusion of hydrogen at temperatures higher than 500°C. Low temperature (⩽400°C) annealing of the PECVD Si₃N ₄ provides efficient hydrogen bulk passivation, while higher temperature annealing relaxes the deposition induced stress and improves mainly the short wavelength (blue) response of the solar cells     

Survey of material options and issues for thin film silicon solar cells

The high production cost of thick high-efficiency crystalline silicon solar cells inhibits widespread application of photovoltaic devices whereas the most developed of thin film cell technologies, that based on amorphous silicon, suffers inherent instability and low efficiency. Crystalline thin-film silicon solar cells offer the potential for a long-term solution for low cost but high-efficiency modules for most applications. This paper reviews the progress in thin-film silicon solar cell development over the last two decades, including progress in thin-film crystal growth, device fabrication, novel cell design, new material development, light trapping and both bulk and surface passivation. Quite promising results have been obtained for both large-grain (>100 μm) polycrystalline silicon material and the recently developed microcrystalline silicon materials. A novel multijunction solar cell design provides a new approach to achieving high-efficiency solar cells from very modest quality and hence low-cost material. Light trapping is essential for high performance from thin-film silicon solar cells. This can be realized by incorporating an appropriate texture on the substrate surface. Both bulk and surface passivation is also important to ensure that the photogenerated carriers can be collected effectively within the thin-film device. © 1998 John Wiley & Sons, Ltd.     

Silicon deposition on mullite ceramic substrates for thin-film solar cells

Fabrication of silicon thin film (TF-Si) solar cells with high throughput on cheap substrates requires both adequate deposition technique and suitable substrate. Our approach consists of depositing polycrystalline silicon films with thickness of 10–30 μm by Rapid Thermal Chemical Vapour Deposition (RT-CVD) onto newly developed mullite ceramics. Compared to alumina, the latter has the advantage that the thermal expansion coefficient can be matched to that of silicon by compositional adjustment. The substrates are elaborated by the tape casting process, enabling continuous production on large size (≥50 cm width). The polycrystalline silicon thin film with structure p+/p is deposited at atmospheric pressure by RT-CVD, tailoring in-situ the temperature and doping profiles. High deposition rates of 1–5 μm/min are commonly obtained in the temperature range 1000–1200°C. In the present paper, the overall optical, crystalline and electrical features of TF-Si on mullite ceramics are presented. Copyright © 1999 John Wiley & Sons, Ltd.     

激光晶化制备多晶硅薄膜技术

激光晶化是一种制作晶硅薄膜器件(如薄膜晶体管、太阳能电池)很有效的技术.展望了低温多晶硅薄膜的应用前景,详细介绍了近几年激光晶化制备多晶硅薄膜技术的研究成果,并就激光对非晶硅作用的原理作了简单讨论.     

ZnO nanorod arrays as an antireflective coating for Cu(In,Ga)Se2 thin film solar cells

A ZnO nanorod antireflective coating has been prepared on Cu(In,Ga)Se₂ thin film solar cells. This coating leads to a decrease of the weighted global reflectance of the solar cells from 8.6 to 3.5%. It boosts the solar cells short‐circuit current up to 5.7% without significant effect on their open‐circuit voltage and fill factor (FF), which is comparable to a conventional optimized single layer MgF₂ antireflective coating. The ZnO nanorod antireflective coating was electrochemically prepared from an aqueous solution at 80°C. The antireflective capability of ZnO nanorod arrays (ZNAs) may be further improved by optimization of growth conditions and their geometry. Copyright © 2010 John Wiley & Sons, Ltd.     

New technologies for production of polycrystalline silicon for solar power engineering

Problems of production of polycrystalline silicon for solar cells at present and in the near future are considered. New promising technologies (implemented already for small-scale production) and some unique recent developments are presented. In particular, the process of reduction of silicon oxides in the gaseous phase is very promising for production of high-purity silicon.     

a-Si:C:H and a-Si:N:H Thin Films Obtained by PECVD for Applications in Silicon Solar Cells

Hydrogenated amorphous silicon-carbon (a-Si:C:H) and hydrogenated silicon-nitrogen (a-Si:N:H) antireflective films were deposited by plasma-enhanced chemical vapor deposition (PECVD) at 13.56 MHz in SiH₄ + CH₄ and SiH₄ + NH₃ gaseous mixtures of various compositions. The silicon and glass samples were investigated by optical spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). A correlation between film properties and process parameters was found. The refractive index decreased and the energy gap increased with an increase of carbon and nitrogen in the films. For some process parameters, it was possible to obtain smooth, hydrogen rich, and homogeneous films of low reflectivity. The silicon solar cells with antireflective coatings revealed an increase in efficiency.     

High efficiency inversion layer solar cells on polycrystalline silicon by the application of silicon nitride

Plasma enhanced CVD silicon nitride is introduced for the fabrication of inversion layer solar cells on p-type polycrystalline silicon. The same high interface quality as obtained for Si-nitride on monocrystalline silicon could also be achieved for polycrystalline silicon. This includes high interface charge densities up to 6.6 × 10¹²cm^-2and high UV sensitivity of the cells. For 4-cm²polycrystalline metal-insulator-semiconductor inversion layer (MIS/IL) solar cells active area efficiencies up to 13.4 percent (12.3-percent total area efficiency) under AM1 illumination could be reached, the highest values yet reported for polycrystalline silicon inversion layer solar cells on a total area basis. For the coprocessed MIS/IL cells on monocrystalline 0.7-ω. cm p-Si     

双光栅结构薄膜太阳能电池的优化

为了提高单晶硅薄膜太阳能电池短路电流密度和转换效率, 采用在单晶硅薄膜太阳能电池正背面分别集成硅介质光栅和铝金属光栅的方法, 并利用有限时域差分法软件仿真研究了两种光栅的周期、厚度、占空比对单晶硅薄膜太阳能电池短路电流密度和光转换效率的影响。结果表明, 通过优化可得当正背面光栅都处于最优值时(介质光栅占空比F=0.8、介质光栅周期P=0.632μm、介质光栅厚度h_g=0.42μm; 金属光栅占空比F₁=0.9、金属光栅周期P=0.632μm、金属光栅厚度h_m=0.005μm), 短路电流密度可达35.15mA/cm2, 转换效率为43.35%;将最优光栅单晶硅薄膜太阳能电池与传统单晶硅薄膜太阳能电池对比, 无论是光程路径还是吸收效率, 光栅单晶硅薄膜太阳能电池都有显著的提高。这为以后制备高性能薄膜太阳能电池提供了理论指导。     

Characterization of laser carved micro channel polycrystalline silicon solar cell

In this study the efficiency of polycrystalline silicon solar cells was increased carving micro channel structures using a laser. In research to date, micro channel structures on the surface of polycrystalline silicon solar cells have been manufactured and studied. In an experiment polycrystalline silicon solar cell with micro channel structures on the surface demonstrated an increase in efficiency of 0.23-1.50%, as the radius of the micro channel structures varied from 15 μm to 35 μm. Micro channels also improved the Fill Factor of polycrystalline silicon solar cells. However, the efficiency started to decrease when the radius of the micro channel structures was greater than 40 μm. Detailed features of the variation in current voltage of polycrystalline silicon solar cells with micro channels are discussed.     

多晶硅太阳电池PECVD氮化硅钝化工艺的研究

介绍等离子体化学气相淀积(PECVD)制备减反射钝化膜。将PECVD设备运用于太阳电池生产线上,发现通过PECVD设备可以对多晶硅太阳电池有很好的钝化效果。分析PECVD对多晶硅太阳电池钝化机理。     

Through‐the‐glass spectroscopic ellipsometry for analysis of CdTe thin‐film solar cells in the superstrate configuration

Polycrystalline CdS/CdTe thin‐film solar cells in the superstrate configuration have been studied by spectroscopic ellipsometry (SE) using glass side illumination. In this measurement method, the first reflection from the ambient/glass interface is rejected, whereas the second reflection from the glass/film‐stack interface is collected; higher order reflections are also rejected. The SE analysis incorporates parameterized dielectric functions ε for solar cell component materials obtained by in situ and variable‐angle SE. In the SE analysis of the complete cells, a step‐wise procedure ranks the fitting parameters, including thicknesses and those defining the spectra in ε, according to their ability to reduce the root‐mean‐square deviation between the simulated and measured SE spectra. The best fit thicknesses from this analysis are found to be consistent with electron microscopy. Based on the SE results, the solar cell quantum efficiency (QE) can be simulated without any free parameters, and comparisons with measured QE enable optical model refinements as well as identification of optical and electronic losses. These capabilities have wide applications in photovoltaic module mapping and in‐line monitoring. Copyright © 2016 John Wiley & Sons, Ltd.     

Polycrystalline silicon thin‐film solar cells on glass by aluminium‐induced crystallisation and subsequent ion‐assisted deposition (ALICIA)

A research project is under way at The University of New South Wales aiming at the realisation of a novel type of polycrystalline silicon thin‐film solar cell on glass. The idea is to first create a thin large‐grained polycrystalline seed layer on glass by aluminium‐induced crystallisation of amorphous silicon and then to epitaxially thicken the seed layer with ion‐assisted deposition. By mid‐2003 this ALICIA project had achieved laboratory cells with voltages of up to 163 mV, as reported elsewhere. In the present paper we give an overview of recent progress (improved Si epitaxy process, improved control of base doping profile due to the use of phosphorus dopants instead of gallium, hydrogen passivation) that has improved the voltages of ALICIA solar cells to 270 mV. Furthermore, the strategy for further voltage improvements is presented. At the present point in time only the voltages of ALICIA cells are known, but obviously solar cells also require current for good efficiency. Hence much improvement in both voltage and current is still needed. Copyright © 2004 John Wiley & Sons, Ltd.     

表面处理对低成本多晶硅太阳电池性能的影响

通过沉积SiNx薄膜和H2退火表面处理工艺对低成本多晶硅太阳电池进行了处理,对表面处理前后的电池效率进行了对比测试,详细地研究了这两种表面处理工艺对电池的短路电流、开路电压、填充因子和转换效率的影响。实验发现,沉积了SiNx薄膜的低成本多晶硅太阳电池的效率在原有基础上提高了1.8%左右;而经过H2退火后的电池效率则出现了效率衰减。与此同时,对成本相对高的太阳能级多晶硅电池也进行了H2退火,与低成本多晶硅电池相比,其效率增加明显,与低成本太阳电池呈现了相反的现象。最后分析了两种表面处理工艺对电池性能造成影响的原因。