Next Generation Perovskite Solar Cell Structures

随着英国政府的目标是到2050年将碳排放量减少80%，对可再生能源的需求比以往任何时候都多。太阳能光伏发电可以直接利用太阳能（我们最丰富的可再生能源）将光转化为电。光伏发电是最具吸引力的可再生能源之一，因为它们可以在小规模或大规模上提供清洁电力，对当地环境的影响最小。商业上使用的光伏电池的主要形式是硅太阳能电池。Percent太阳能电池（PSC）是一种令人兴奋的新型太阳能电池，其具有比硅太阳能电池更薄、更便宜、更灵活的潜力，同时实现类似的效率和更低的制造能源成本。我的目标是进一步提高PSC的潜力，将其设计改为“背接触”结构，可以提高其性能，同时降低材料成本，并使其更容易优化其操作。PSC由3个关键部分组成-一个将光转化为电的吸收器和两个用于提取电荷的触点。在普通的太阳能电池中，这些层像三明治一样堆叠在一起，吸收体位于中间。这意味着光必须穿过夹层的顶层才能到达吸收器，这意味着除非顶层由非常昂贵的透明和导电材料制成，否则其中一些会丢失。背接触式电池通过在吸收器的底部上以蜂窝图案或作为彼此交织的一组指状物来具有两个触点来克服这一点。这使得吸收器的顶部可以自由吸收光线，没有其他层的阻碍。背接触结构与标准的PSC制作方法相比有很多优点，但由于其制作难度比标准结构更大，因此迄今为止还没有对其进行详细的研究。背接触式PSC中的互锁金属指必须比人类头发宽度的百分之一更薄，同时覆盖平方米量级的面积。因此，到目前为止，还没有人能够以具有成本效益或可扩展的方式做到这一点。Permos激光器通常是衍射光栅，其结构与背接触太阳能电池所需的图案非常相似，使用称为纳米压印光刻的工艺。这涉及以所需的图案制作印模，然后将特征物理地压入材料中。这是一种廉价的工艺，可以在大面积上快速制作图案，在这个项目中，我将把这种技术应用于钙钛矿太阳能电池而不是衍射光栅。这将使用可以容易地在工业上扩展的技术在大面积上实现高效的背接触PSC。使背接触式PSC的生产变得容易可以帮助制造比夹层结构更高效率的PSC，同时降低其材料成本并消除几个设计限制。背接触电池还能够研究吸收体材料的物理特性，这在夹层结构中是不可能的。这些实验将大大提高我们对PSC工作原理的理解，并将加快研究，以帮助找到新的和改进的材料，从而实现更高的效率。这将有助于太阳能与化石燃料竞争，甚至变得比化石燃料更便宜，从而为绿色能源的新革命铺平道路。

With the UK government's target to reduce carbon emissions by 80 % by 2050, there is more demand than ever for renewable energy. Solar photovoltaics can directly harness the power of the sun (our most abundant source of renewable energy) by turning light into electricity. Photovoltaics are one of the most attractive sources of renewable energy because they can provide clean electricity on small or large scales with minimal impact on the local environment. The main form of photovoltaic cells used commercially are silicon solar cells.Perovskite solar cells (PSCs) are an exciting new class of solar cell which have the potential to be flexible, thinner, and cheaper than silicon solar cells while achieving a similar efficiency with a lower energy cost of manufacture. I aim to improve the potential of PSCs even further by altering their design to a "back-contact" structure that could increase their performance whilst reducing material costs and making it easier to optimise their operation. A PSC is made from 3 key parts - an absorber for turning light into electricity, and two contacts for extracting the charge. In a normal solar cell these layers are stacked on top of each other like a sandwich, with the absorber in the middle. This means that light has to pass through the top layer of the sandwich in order to reach the absorber, meaning some of it is lost unless the top layer is made from very expensive materials which are both transparent and conductive. A back-contact cell overcomes this by having both contacts on the bottom of the absorber in a honeycomb pattern, or as a set of fingers interwoven with each other. This leaves the top of the absorber free to absorb light with no other layers getting in the way. The back-contact structure has lots of advantages over the standard way of making PSCs, but it has not been studied in detail so far because it is harder to make than the standard structure. The interlocking metal fingers in a back-contact PSC must be thinner than a hundredth of the width of a human hair, whilst covering areas in the order of square meters. Because of this, nobody has been able to do this in a cost effective or scalable way so far. Perovskite lasers are frequently made diffraction gratings, which have very similar structures to the patterns needed in a back-contact solar cell, using a process called nanoimprint lithography. This involves making a stamp in the desired pattern and then physically pressing the features into the material. This is a cheap process which can make patterns quickly over large areas, and in this project I will adapt this technique for perovskite solar cells instead of diffraction gratings. This will enable efficient back-contact PSCs on large areas using a technique that could easily be scaled industrially. Enabling the easy production of back-contact PSCs could help make PSCs with higher efficiency than the sandwich structure, whilst simultaneously reducing their material costs and removing several design constraints. A back-contact cell also enables studies of the physics of the absorber materials which are impossible in the sandwich structure. These experiments will greatly enhance our understanding of how PSCs work, and will speed up research to help find new and improved materials which achieve even higher efficiency. This could help solar power compete with or even become cheaper than fossil fuels, thus paving the way for a new revolution in green energy.