非晶硅太阳电池的研发进展

2004年第2期综观全球,由工业化造成的能源短缺,温室效应和环境污染已经成为3个全球性难题。发展新能源已经成为可持续发展战略的重要组成部分。专家分析预测,未来光伏产业发展的年增长率在20～30%之间,光伏发电将很快发展成巨大的市场。与燃煤比较,光伏发电1MWh(兆瓦·时)电力可少产生1000tCO2排放。到本世纪的二三十年代,太阳能发电成本有可能降低到与常规电价相竞争的水平,一个广泛的大规模利用太阳能和可再生能源的新时代正在来临。非晶硅太阳电池由于生产成本较低、工艺简单、节省原料等优点在太阳能光伏发电方面具有很大优势。本文就…     

一种治疗非晶硅太阳电池缺陷的新方法

用“电压法”,治疗ａ．Ｓｉ薄膜太阳电池,烧断ｐｎ结中漏电沟道,使被治疗样品的性能变坏。“库仑法”根据样品漏电多少,决定用于治疗电池的电荷积分多少,没有剩余电荷,不会影响电池性能,可用于ａ．Ｓｉ薄膜电池的研究与规模生产。     

非晶硅合金太阳电池的最新进展

１９９７年非晶硅合金太阳电池技术的研究取得两大显著进展。第一,采用光谱分离三叠层结构制备的非晶硅太阳电池转化效率达到１３％,创下新的世界纪录;第二,三叠层结构太阳电池年生产能力达５ＭＷ,并已有多种产品出售。１对太阳电池的要求开发太阳电池的两个关键问...     

非晶硅太阳电池中的非欧姆夹层

a-Si pin太阳电池暗态下存在一种串联电阻效应,并呈非线性特性。由于它的存在,使暗态电流对数值与电压之间明显偏离线性关系。该非线性电阻在高正向电压下趋于饱和,呈现集总电阻效应。从不同光强下电池串联电阻R_s和短路电流I_(sc)关系推算出的接触电阻值与上述非线性电阻的饱和值相符甚好,说明此电阻效应可能与接触特性有关。 计入非线性电阻后标出的暗态二极管参数(品质因子n、反向饱和电流I_o)与光态二极管参数(n_L、I_(oL))非常接近,在一定程度上由暗态I—V特性算出的V_(oc)与实测值一致性很好。因此认为,可由暗态I—V特性评估电池性能。     

新型非晶硅太阳电池

论述了新型非晶硅太阳电池的发展，介绍了See-Through Amorton半透明太阳电池、a-Sic激活层半透明太阳电池，弱光太阳电池，不透明柔性衬底太阳电池，透明柔性衬底太阳电池及导电聚合物柔性衬底太阳电池的特性，并且介绍了国内新型非晶硅太阳电池的研究成果及应用。     

非晶硅薄膜太阳电池应用分析

简要介绍了当前几种薄膜太阳电池,并分析了它们的优缺点;详细介绍了非晶硅薄膜太阳电池,分析了其光致衰退效应与影响光电性能的各种因素,总结并展望了优化非晶硅太阳电池的各种技术。     

Fabrication technology for large-area a-Si solar cells

The fabrication process technology for large-area a-Si photovoltaic (PV) modules and their performance are reviewed. Our present technology enables us to provide 10% efficient large-area submodules with a stabilized efficiency of 8.5%. To study the practicability of the a-Si solar panels, we carried out an outdoor test for our a-Si modules. The results show that the a-Si solar PV modules generate power very efficiently in outdoor systems. The advantage of the a-Si modules under outdoor uses is presented and discussed.     

Numerical approach for high-efficiency a-Si solar cells

We have developed the first precise numerical simulator for thin-film solar cells with two-dimensional structures, such as a submicron textured a-Si solar cell. Conventional simulators for thin-film solar cells were all one-dimensional, which made precise simulation of the behavior of light and carrier transport in the cell impossible. Using the 2D simulator, guidelines for cell design, including textured structures, were obtained. One proposal to increase the conversion efficiency of the textured a-Si single-junction solar cell is to make the texture period longer than the film thickness.     

Development and application of see-through a-Si solar cells

A new type of translucent amorphous silicon (a-Si) solar cell, called the see-through a-Si solar cell, is developed. It has multiple microscopic holes within its effective area to transmit light and it generates electric power. A series of technical data on the fabrication processing with various patterning and photovoltaic performance are presented. Some examples of application systems such as car sunroof and home interior are introduced and discussed on a wide variety of new areas of PV applications. The see-through a-Si solar cell was mounted on a car sunroof to drive the car's ventilating system or to charge its battery. The ventilating system reduced the interior temperature of the car from 61 to 47°C during daytime parking.     

a-Si alloy three-stacked solar cells with high stabilized-efficiency

a-Si alloy three-stacked solar cells have been studied to improve the stabilized efficiency of a-Si: H based solar cells. Based on the analysis by the individual characterization method of the component cells in stacked type cells, the a-Si :H middle cell was replaced with an a-SiGe :H cell. Furthermore, the optical confinement technology was improved to obtain a high-output current with thin i-layer thickness in the a-SiGe :H bottom cell. By this device design, the initial conversion efficiency was improved up to 12.4% and more than a 10% stabilized efficiency was obtained in a-SiC :H/a-SiGe :H/a-SiGe :H three-stacked cells. These cell characteristics were confirmed by measurements at the JQA Organization (the former JMI Institute).     

Modeling of a-Si/poly-Si and a-Si/poly-Si/poly-Si stacked solar cells

A computer model for the poly-Si thin film-related solar cells is established, with which the solar cells with the structure of single junction poly-Si cell, a-Si/poly-Si tandem cell and a-Si/poly-Si/poly-Si triple cell are simulated. The results indicate that the practical structure for poly-Si-related solar cell is a-Si/poly-Si/poly-Si triple cell with the best matched thickness of 0.23/0.95/3 μm and with optical confinement structure, which has the highest simulated efficiency of 22.74%.     

Limiting carrier effect in a-Si:H solar cells

The limiting carrier effect in a-Si:H p–i–n and n–i–p solar cells has been investigated computationally, by adjusting the values of the carrier band mobilities. Using a realistic optical generation rate profile, it was found that the effect is significant in both types of cell, with the electron identified as the limiting carrier in the p–i–n cell, and the hole in the n–i–p cell. However, using a uniform generation rate profile in the simulation indicated that the limiting carrier effect was much less significant, and that device performance in both cells seemed to be slightly more sensitive to the hole transport properties than to the electron transport properties.     

Single-junction a-Si solar cells with over 13% efficiency

Single junction hydrogenated amorphous silicon solar cells having a high conversion efficiency of 13.2% were developed by combining three approaches. First, a new type of p-layer, such as (a-Si/a-C)_n multilayers, was investigated. The high open-circuit voltage was obtained without lowering the short-circuit current and the fill factor. Second, alternately repeating deposition and hydrogen plasma treatment method was applied to the fabrication of an a-SiC or wide gap a-Si : H films for p/i interface layer. High photoconductive and wide bandgap materials were obtained applicable to the p/i buffer layers. Third, the relationships between defect density of films or fill factors of solar cells and hydrogen radical in plasma were investigated. It was suggested that the H^*/SiH^* ratio was an effective parameter to improve the defect and fill factor, and the excess hydrogen radical deteriorated quality of films and cells.     

Optically induced degradation in a-Si:H solar cells

Difference spectra of optically induced changes in the surface photo-voltage response of a-Si:H solar cells show that illumination generates two sets of near midgap states which have energy levels consistent with the two energy states for dangling bond defects in this material. Recombination of photo-generated carriers in these states leads to significant degradation of cell performance for photon energies larger than the bandgap. At low temperature (−160°C), the difference spectrum indicates that although the defect states are still present, such degradation does not occur.     

Advanced fabrication technologies of integrated-type structure for a-Si solar cells

This paper proposes a new advanced fabrication technology for a low-cost integrated-type a-Si solar cell. Integrated-type cells provide many advantages and have been industrialized with a laser patterning method. However, a higher throughput and more efficient patterning method was required for applying a-Si solar cells to a power generating system. Plasma CVM (Chemical Vaporization Machining) was first applied to advanced patterning because of its advantages of high speed and selectivity. In this method, a plasma generated under high pressure localizes near the wire electrode and concentrates reactive radicals. As a result, we achieved an etching rate of more than 1 μm/s and selective patterning of a 200 μm-wide a-Si layer in 1 s multiline patterning was also developed for large-area modules.     

Optical confinement in high-efficiency a-Si solar cells with textured surfaces

The experimental spectral response and reflectance of high-efficiency a-Si solar cells are systematically investigated by using an optical simulation based on realistic optical properties of the transparent conducting oxide (TCO), a-Si, and metal electrode, in order to improve the spectral response. It is shown that a practically important optical loss results from absorption by the TCO, which is enhanced by the optical confinement effect. This suggests that improvement in the spectral response is possible by suppressing the optical confinement in the TCO.