Enhanced multiple exciton generation in colloidal quantum dots

太阳能是最有希望替代石油、天然气和煤炭来产生我们所需能源的能源之一。阳光是免费的，安全的，而且从太阳到达地球的阳光足够提供我们所需的一万倍的能量。它也很清洁，不会像化石燃料那样向大气中释放二氧化碳，而二氧化碳有可能导致破坏性的气候变化。然而，今天的太阳能电池还不经济；燃烧化石燃料发电仍然更便宜，这阻碍了它们的广泛使用。我们如何使太阳能电池在经济上与化石燃料竞争？有两种方法：使它们更便宜或使它们更有效，或者最好两者兼而有之！你今天看到的大多数太阳能电池都是由硅制成的，效率高达20%，但制造成本很高。一些更新的、不同类型的电池开始出现，它们的制造成本要低得多，但效率最多只有10%。这个项目的目的是两全其美——太阳能电池既便宜又高效，足以与化石燃料竞争。这些新电池的关键部分将是“量子点”——这些微小的半导体晶体将吸收阳光并将其转化为电能。在今天的太阳能电池中，大约一半来自太阳的能量一旦被电池吸收就会以热量的形式浪费掉。然而，在量子点中，可能会发生其他事情——在正常电池中成为废热的能量可以用来产生额外的电力。这意味着基于量子点的太阳能电池的效率可能比目前的技术高出50%。这是一个令人兴奋的前景，可能很重要，但我们仍然需要更好地理解这个过程。在这个项目中，我们将生产新型量子点，旨在最大限度地提高阳光转化为电能的效率。这些点还必须由廉价、丰富和安全的材料制成。我们将用x射线仔细研究它们的结构，用激光研究光被吸收时发生了什么。复杂的计算机模型将用于帮助我们更好地了解正在发生的事情，并尽可能有效地将阳光转化为电能。最后，我们将用这些新的量子点制造一个原型太阳能电池，这将展示它们如何被用来安全、清洁和廉价地发电。

Solar power is one of the most promising alternatives to using oil, gas and coal to generate the energy we need. Sunlight is freely available, safe and enough of it reaches the earth from the sun to supply all our energy needs 10,000 times over. It is also clean, releasing none of the carbon dioxide in to the atmosphere that fossil fuels do and which threatens to cause damaging climate change. However, today's solar cells are not yet economic; it is still cheaper to produce power by burning fossil fuels and this is preventing their wide-spread use.How can we make solar cells economically competitive with fossil fuels? There are two ways: make them more cheaply or make them more efficient, or preferably both! Most of the solar cells you see around today are made from silicon and are up to 20% efficient but are expensive to make. Some newer, different types of cell are beginnning to become available which are a lot cheaper to make but are only 10% efficient at most. The aim of this project is to have the best of both worlds - solar cells that are both cheap and efficient enough to compete with fossil fuels.The key part of these new cells will be 'quantum dots' - these are tiny crystals of semiconductor that will absorb the sunlight and turn it into electricity. In today's solar cells, about half of the energy from the sun is wasted as heat as soon as the sunlight is absorbed by the cell. In quantum dots, however, something else can happen - the energy that would become waste heat in a normal cell can be used instead to produce extra electricity. This means that solar cells based on quantum dots could be up to 50% more efficient than today's technology.This is an exciting prospect and could be important but we still need to understand this process better. In this project, we will produce new types of quantum dots which are designed to maximise the effciency with which sunlight is turned into electricity. These dots must also be made from materials which are cheap, abundant and safe. We will use X-rays to study their structure carefully and lasers to study what happens to the light as it is absorbed. Complex computer models will be used to help us better understand what is happening and make the conversion of sunlight to electricity as efficient as it can be. Finally, we will build a prototype solar cell using these new quantum dots which will demonstrate how they can be used to generate electricity safely, cleanly and cheaply.