Improved surface passivation for semiconductor solar cells

目前，世界正在经历工业革命以来最大的能源使用变革之一。从最贫穷的国家到最富裕的国家，我们的星球已经显示出气候变化的后果，一些化石燃料的枯竭现在已经在可预见的未来。我们已经开始改变我们在世界各地生产、分配和使用能源的方式。太阳能是对环境最有利的能源之一，原则上可以提供地球所需的所有能源。太阳能电池利用光伏效应将太阳能转化为可用电能，因此是向世界提供可再生、廉价和可靠电力的关键技术。在过去的二十年里，光伏研究和工业经历了巨大的进步。到目前为止，光伏领域最重要的材料是硅。如今，硅占光伏市场的85%以上，装机容量超过140千兆瓦。目前的硅太阳能电池系统的能量回收期只有2-4年，寿命为30年。它们的发电成本现在降到了0.5美元/瓦以下，在世界上的一些地区，它们提供电网电力已经具有成本效益。因此，硅光伏是一种非常有前景的技术，仍有可能进行重大的技术改进，这将确保进一步降低价格和增加部署。当太阳能电池表面附近的光被吸收时，硅太阳能电池就会吸收太阳能，并产生电荷载流子。然后，这些携带者在细胞中扩散，在其中一个触点收集，然后能够输送电力。在这个过程中，由于材料的缺陷，许多载体都会丢失。因此，太阳能电池的转换效率受到缺陷和缺陷处载流子的这种损失的限制。电池的表面代表了一个主要的材料缺陷。因此，被称为钝化的表面电荷损失的减少是需要改进的关键特征。这个项目旨在通过优化钝化来提高硅太阳能电池的效率，该技术是我之前研究工作的一部分，提出并获得了专利。一项新提出的技术可以使商业太阳能电池的钝化效率发生阶梯变化，这是很少见的。这一赠款申请将特别使这一步骤的改变得以发展。我的研究项目包括太阳能电池制造中使用的不同钝化涂层的制备、加工和表征。将研究不同的制备涂层和提高其钝化性能的方法。沉积涂层的技术将包括化学和物理气相沉积。在每种情况下，关键的重要性将是关于存储将特别引入的过剩电荷的层的特性。这项研究将在牛津材料部门与四家英国制造公司和领先的海外研究中心弗劳恩霍夫太阳能系统研究所(Fraunhofer Institute For Solar Energy Systems ISE)密切合作进行。该研究所将提供加工和表征设施、员工时间和最先进的定制太阳能电池，并将帮助将这一合作的成果与全球太阳能电池行业相结合。总体而言，该项目将结合一支强大的学术界和产业界团队，以提高半导体太阳能电池的效率和降低成本，从而为广泛部署和采用一项有潜力为世界提供丰富的可再生和可靠能源的技术铺平道路。

The world is currently undergoing one of the biggest transformations in energy usage since the industrial revolution. From the poorest to the richest nations, our planet has shown the consequences of climate change, and the exhaustion of some fossil fuels is now in the foreseeable future. We have started to change the way we generate, distribute and use energy throughout the world. Solar power is one of the most environmentally favourable sources, which in principle could provide all the energy required for the planet. Solar cells use the photovoltaic effect to convert solar energy to usable electrical energy, and thus are a key technology to provide the world with renewable, inexpensive and reliable electricity. Photovoltaics research and industry have experienced enormous advancements in the last two decades. The most important material by far in the photovoltaics field is silicon. Silicon today accounts for over 85 % of the photovoltaics market, and has over 140 GW of installed capacity. Current silicon solar cell systems have an energy payback time of only 2-4 years with 30-years lifetime. Their cost of power generation is now falling below 0.5 $/W, and in some areas of the world they are already cost effective for supplying grid electricity. Silicon photovoltaics is therefore an extremely promising technology where significant technological improvements are still possible which will ensure further price reductions and increased deployment. Silicon solar cells capture solar energy when light is absorbed near the cell's surface and it creates electrical charge carriers. These carriers then diffuse through the cell, get collected at one of the contacts and are then able to deliver electricity. In this process many carriers are lost due to the imperfections of the material. The conversion efficiency of a solar cell is therefore limited by this loss of charge carriers at imperfections and defects. The surface of the cell represents a major material defect. The reduction of charge loss at the surface, termed passivation, is hence a critical feature requiring improvement. This project aims to improve the efficiency of silicon solar cells by optimising passivation using the cost-effective technologies proposed and patented as part of my previous research work. It is rare that a newly proposed technique could produce a step-change in the efficiency of passivation in commercial solar cells. This grant application will specifically enable that step-change to be developed. My research programme includes the fabrication, processing and characterisation of different passivation coatings used in solar cell manufacture. Different methods of producing the coatings and enhancing their passivation properties will be studied. Techniques to deposit the coating will include chemical and physical vapour deposition. In each case the key importance will be the characteristics of the layer with respect to storing excess electric charge that will be especially introduced. The research will be carried out at the Oxford Materials department, in close partnership with four UK manufacturing companies and a leading overseas research centre, the Fraunhofer Institute for Solar Energy Systems ISE. This institute will provide processing and characterisation facilities, staff time and state-of-the-art custom-made solar cells, and will also help interface the outcomes of this collaboration to the solar cell industry worldwide. Overall, this project will combine a strong team of academics and industry to improve efficiency and reduce the cost of semiconductor solar cells, thus paving the way for wide deployment and uptake of a technology with the potential to provide the world with abundant renewable and reliable energy.