Elimination of Efficiency Degradation Mechanisms in Silicon Photovoltaic Solar Cells

消除硅光伏太阳能电池效率下降的机制

• 批准号: EP/H019987/1
• 负责人: Bruce Hamilton
• 金额: $ 34.15万
• 依托单位: University of Manchester
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH019987%2F1
• 关键词: Elimination; Efficiency; Degradation; Mechanisms; Silicon

Photovoltaic Solar Cells seem certain to make a significant contribution to the world's energy needs in the 21st Century. At the present time such devices only convert a small part of the 1kW per square meter of radiation from the sun which falls on the earth's surface into electricity. Typical commercial silicon devices that use un-concentrated sunlight are less than 15% efficient although laboratory devices with efficiencies as high as 24% have been made. Many very interesting ideas have been put forward for higher efficiency 3rd generation cells but most of these are a very long way from commercial realization on a large economic scale. At the present time 90% of production is based on wafered silicon (Czochralski single crystal or cast poly-crystalline). The predicted production for 2010 using existing silicon technology will have a peak output of 26GW. Unfortunately in their initial few hours of operation most silicon solar cells suffer from degradation which stabilizes after a reduction in efficiency of 10% relative ie a 20% cell becomes an 18% cell. In the context of total photovoltaic power lost on a world scale this is very significant. It is believed that the reduction in efficiency is due to a defect reaction in the silicon in which oxygen dimers diffuse to the boron dopant to form a powerful recombination centre. The problem is not restricted to the commercial devices of the next decade but is also highly relevant to some of the most promising third generation (high efficiency) cells which use silicon as part of the active structure. This research proposal aims to eliminate the degradation process by removing the reaction path from the silicon prior to the formation of the recombination centre. An essential pre-requisite to this is to achieve a detailed understanding of the defect centres and their formation.We have previously studied the oxygen dimers which are currently thought to be the precursors of the recombination centre. These can be detected using optical absorption measurements, ideally at low temperatures (~10K). Preliminary work indicates that it should be possible to develop treatments of the silicon material which reduce the concentration of the dimers to a negligible level in the finished cell and, because the dimers do not form at normal operating temperatures, so eliminate the formation of the defect. It would be quite feasible using this approach to maintain the concentration of interstitial oxygen which provides mechanical strength to the silicon with consequent yield and cost benefits. In this work the recombination centre will be studied using minority carrier Laplace Deep Level Spectroscopy and its structure determined by the application of uniaxial stress. The reaction of the oxygen dimer will be studied as the recombination centre forms, in real time, using optical absorption techniques. The work will be done in collaboration with MEMC who are one of the leading manufactures of solar silicon, the Institut fr Solarenergieforschung Hameln/Emmerthal (ISFH) in Germany who have undertaken much experimental work recently on solar cell degradation and the University of Aveiro in Portugal who will collaborate on theoretical calculations to support the Manchester work.

光伏太阳能电池似乎肯定会对21世纪的世界能源需求做出重大贡献。目前，这种装置只能将落在地球表面的每平方米1千瓦的太阳辐射中的一小部分转化为电能。典型的商业硅设备使用不集中的阳光，效率低于15%，尽管实验室设备的效率高达24%。对于效率更高的第三代电池，人们提出了许多非常有趣的想法，但其中大多数距离大规模的商业实现还有很长的路要走。目前90%的产品是基于硅片（Czochralski单晶或铸造多晶）。利用现有的硅技术，预计2010年的产量峰值将达到26GW。不幸的是，在最初的几个小时内，大多数硅太阳能电池都会出现退化，相对于20%的电池变成18%的电池，在效率降低10%后就会稳定下来。在全球光伏发电总量损失的背景下，这是非常重要的。据信，效率的降低是由于硅中的缺陷反应，其中氧二聚体扩散到硼掺杂物中形成强大的复合中心。这个问题不仅限于未来十年的商用设备，而且还与一些最有前途的第三代（高效率）电池高度相关，这些电池使用硅作为有源结构的一部分。本研究计划旨在通过在重组中心形成之前从硅中去除反应路径来消除降解过程。要做到这一点，一个必要的先决条件是对缺陷中心及其形成有详细的了解。我们以前研究过氧二聚体，目前认为它们是重组中心的前体。这些可以使用光学吸收测量来检测，理想情况下是在低温（~10K）下。初步工作表明，应该有可能开发出将硅材料的二聚体浓度降低到成品电池中可以忽略不计的水平的处理方法，并且由于二聚体在正常工作温度下不会形成，因此可以消除缺陷的形成。使用这种方法来维持间隙氧的浓度是非常可行的，这为硅提供了机械强度，从而带来了产量和成本效益。在这项工作中，将使用少数载流子拉普拉斯深能级光谱研究复合中心，并通过应用单轴应力确定其结构。利用光学吸收技术实时研究氧二聚体在复合中心形成时的反应。这项工作将与MEMC合作完成，MEMC是太阳能硅的主要制造商之一，德国的太阳能研究所（ISFH）最近进行了大量关于太阳能电池降解的实验工作，葡萄牙的阿威罗大学（University of Aveiro）将合作进行理论计算，以支持曼彻斯特的工作。

项目成果

Recombination via point defects and their complexes in solar silicon

• DOI: 10.1002/pssa.201200216
• 发表时间: 2012-10
• 期刊: physica status solidi (a)
• 作者: A. Peaker;V. Markevich;B. Hamilton;G. Parada;A. Dudas;A. Pap;E. Don;B. Lim;J. Schmidt;L. Yu;Y. Yoon;G. Rozgonyi

Local vibrational modes of the oxygen trimer in Si

Si 中氧三聚体的局部振动模式

• DOI: 10.1002/pssc.201000280
• 发表时间: 2011
• 期刊: physica status solidi c
• 作者: Murin L

Tin-vacancy complex in germanium

锗中的锡空位配合物

• DOI: 10.1063/1.3574405
• 发表时间: 2011
• 期刊: Journal of Applied Physics
• 影响因子: 3.2
• 作者: Markevich V

Light Induced Degradation of Wafered Silicon Cells: The Boron Oxygen Dilemma

硅片电池的光诱导降解：硼氧困境

• 作者: Vladimir Markevich (Author)

Back Cover: Recombination via point defects and their complexes in solar silicon (Phys. Status Solidi A 10/2012)

封底：通过太阳能硅中的点缺陷及其复合物进行重组（Phys. Status Solidi A 10/2012）

• DOI: 10.1002/pssa.201290026
• 发表时间: 2012
• 期刊: physica status solidi (a)
• 作者: Peaker A