Organometal halide photovoltaic cells: tailoring fundamental light conversion pathways

有大量证据表明，我们日益增加的化石燃料消费和相关的二氧化碳排放正在导致气候变化。这给开发清洁、可再生能源带来了新的紧迫性。收集太阳提供的能量的光伏设备有很大的潜力为解决方案做出贡献，但是基于当前技术的设备的成本削弱了光伏能源发电的吸收。降低成本的关键是开发新的光伏材料，使其易于从溶液或低温蒸发中进行大规模加工，而不需要昂贵的净化和高能沉积。重要的是，在导电塑料或金属箔电极上制造光伏电池将使生产技术从昂贵的半导体加工转变为印刷技术。在过去的1-2年里，基于有机金属卤化物钙钛矿吸收剂的新一代薄膜光伏电池突然出现，随着材料控制和器件协议的改进，其功率转换效率迅速达到15%以上。所采用的甲基铵卤化铅钙钛矿材料允许在空气中进行低成本的溶液处理，并广泛吸收整个太阳光谱，使其成为清洁能源发电的令人兴奋的新组件。该计划的主要目的是建立支撑有机金属卤化物钙钛矿太阳能电池工作的关键参数。最近在这些设备的功率转换效率方面取得的显著进展在很大程度上是偶然的，是通过最初非常成功的试错方法实现的。对控制光到光电流转换的基本参数的清晰理解，现在为进一步开发这类用于光收集技术的材料提供了线索。目前，对于大多数其他光伏材料已经确定的因素，如电荷产生、重组和扩散，以及基本材料参数（如组成、形态、陷阱态和掺杂）的影响，研究界知之甚少。提出的计划非常及时，因为它将引发进一步的效率提高浪潮，而这一浪潮目前主要依赖于更有针对性的材料进步方法。在多方面的方法中，我们将把器件性能研究与先进的光谱研究结合起来，直接确定如何通过材料修改来调整基本过程，并最终呈现光伏效率的新记录。

There is overwhelming evidence that our increasing consumption of fossil fuels and the associated emission of carbon dioxide is leading to climate change. This has brought new urgency to the development of clean, renewable sources of energy. Photovoltaic devices that harvest the energy provided by the sun have great potential to contribute to the solution, but uptake of photovoltaic energy generation has been weakened by the cost of devices based on current technology. The key to reducing cost is the development of new photovoltaic materials allowing easy, large-scale processing from solution or low-temperature evaporation that does not require costly purification and high-energy deposition. Importantly, fabrication of photovolatics on conducting plastic or metallic foil electrodes will transform the production techniques from costly semiconductor processing towards printing technology. To the great surprise of the photovoltaics community, a new generation of thin-film photovoltaic cells based on organometal halide perovskite absorbers emerged suddenly over the last 1-2 years which rapidly reached power conversion efficiencies exceeding 15% as materials control and device protocol improved. The methylammonium lead halide perovskite materials employed allow low-cost solution processing in air and absorb broadly across the solar spectrum, making them an exciting new component for clean energy generation. The key aim of the proposed program is to establish the crucial parameters underpinning the workings of organometal halide perovskite solar cells. The recent remarkable progress in the power conversion efficiencies of these devices has been largely serendipitous, achieved by an initially highly successful trial-and-error approach. Obtaining a clear understanding of fundamental parameters governing light-to-photocurrent conversion now holds the clue to further development of this material class for light-harvesting technologies. Currently, the research community holds little knowledge on factors that have already been well established for most other photovoltaic materials, such as charge generation, recombination and diffusion, as well as the influence of basic material parameters such as composition, morphology, trap states and doping. The presented program is extremely timely, as it will unleash a further wave of efficiency improvements that now crucially relies on a more targeted approach to material advances. In a multi-faceted approach we will combine a study of device performance with advanced spectroscopic investigations, determining directly how fundamental processes can be tuned by materials modifications, and as a result presenting new records in photovoltaic efficiencies.