Nanoscale interface engineering for silicon-based tandem photovoltaics 1=Energy 2=Solar Technology

全世界光伏太阳能电池的安装正在迅速达到太瓦级。其中90%以上使用晶体硅，并且这一市场份额正在增长。最好的单结硅电池的效率高达26.7%，创纪录的电池正在接近硅的最高效率29.4%。通过在硅基电池的顶部放置较宽带隙半导体以形成串联配置，可以超过该限制。这可以使太阳能电池的效率达到35%或更高。这种方法成功的关键是确保在硅基电池成本相对较低的情况下，顶部电池的增量成本是现实的。宽带隙低成本可制造顶电池（例如钙钛矿）的最新进展使得这种串联架构非常及时。如果这些研究取得成功，将对全球可再生能源的生产产生重大影响。硅与宽带隙材料之间的界面是目前需要解决的关键问题。这个博士项目将解决硅和顶部电池之间的界面的基础材料科学，以加速串联电池的开发。超薄钝化膜（< 1 nm）将使用原子层沉积（ALD）生产，当应用于半导体表面时，这些钝化膜表现出优异的热稳定性和电稳定性。目标是在原子尺度上对钝化机制以及如何操纵工艺以实现最佳的长期热和电气性能有一个基本的了解。然后，可以将开发的膜应用于选择的硅基串联光伏架构。

Worldwide installations of photovoltaic solar cells are rapidly reaching the terawatt level. Crystalline silicon is used for more than 90% of these, and this market share is growing. The best single-junction silicon cells have efficiencies of up to 26.7%, and record cells are closing in on silicon's maximum efficiency of 29.4%. This limit can be exceeded by placing a wider bandgap semiconductor on top of the silicon base cell to form a tandem configuration. This could enable solar cells to have efficiencies of 35% or higher. The key to the success of such an approach is to ensure the incremental cost of the top cell is realistic in the context of the relatively low cost of the silicon base cell. Recent advances in wider bandgap low-cost manufacturable top cells (such as perovskites) make such tandem architectures extremely timely. If these are successful they will have a significant impact on global energy production by renewable sources.The interface between the silicon and the wider bandgap material is the key topic to address at present. This PhD project will address the fundamental materials science of the interface between the silicon and the top cell to accelerate the development of tandem cells. Ultra-thin passivation films (< 1 nm) will be produced using atomic layer deposition (ALD), and these exhibit excellent thermal and electrical stability when applied to semiconductor surfaces. The objective will be to develop a fundamental understanding of the passivation mechanism at the atomic scale and how processes can be manipulated in order to achieve optimal long-term thermal and electrical properties. The films developed may then be applied to a selection of silicon-based tandem photovoltaic architectures.