Characterisation of high-performance photovoltaic materials for space applications using a correlative cathodoluminescence/photoluminescence spectrosc

在用于空间应用的光化学方面，高性能一词包括几种材料特性。光伏器件的一个关键要求是高效率，它将许多所需的材料特性联系在一起。卫星的电源是可能的使命目标的限制因素，通常也决定其寿命。因此，对材料的需求使得能够制造高效率的设备，不仅在寿命开始时，而且在恶劣的太空条件下也能保持，这推动了该项目的研究。该项目将探索高效率问题的两个方面，即提高寿命开始时的效率以及任务性能的可持续性。它的目的是通过使用阴极发光和光致发光光谱方法表征材料来实现这一点，这将提高我们对材料光学和电学特性的理解，并为我们提供信息，对材料或器件结构进行重大改进。在这个项目中，我们将开发一种替代高效率概念的材料：热载流子太阳能电池。这种新兴的器件概念可以在薄的、相对简单的和结构优雅的设计中实现高效率。我们将使用发光技术来研究半导体和量子限制结构中的热载流子，包括它们的热化和提取。热化机制的延迟加上热载流子提取效率的提高的进展可能会导致一个新的，从根本上不同的类的photopolics，与效率超越肖克利-奎瑟limit.We还将解决这些材料的辐射损伤的挑战，这是性能恶化的主要原因空间photopolics。撞击辐射在吸收体中引入缺陷，这些缺陷充当光生载流子的非辐射复合位点，因此导致器件效率降低，并因此导致性能降低。上述实验技术可用于有效地研究缺陷部位。计划的相关方法，连同阴极射线发光和光致发光光谱的时间分辨测量能力，可以提供新的洞察缺陷及其在新的器件结构的影响。

In the context of photovoltaics for space applications, the term high-performance encompasses several material properties. A key requirement for the photovoltaic devices and one that ties together many of the desired material properties is that of high efficiency. The power supply to satellites is the limiting factor in the possible mission objectives and usually also determines their lifetime. It is therefore the need for materials that enable the fabrication of high efficiency devices, not only at the beginning of life, but also maintained despite the harsh conditions of space, that drives the research of this project.The project will explore two sides of this high efficiency problem, improvement of both efficiency at beginning of life as well as sustainability of on-mission performance. It will aim to do so through characterization of materials using cathodoluminescence and photoluminescence spectroscopy methods, which will improve our understanding of the optical and electrical properties of materials and give us the information to make vital improvements to materials or device structures.The current industry standard for space power systems is an on-wafer III-V multi-junction technology. In this project we will develop materials for an alternative high efficiency concept: the hot-carrier solar cell. This emerging device concept could enable high efficiency in a thin, comparatively simple and thermodynamically elegant design. We will use luminescence techniques to study hot carriers in semiconductors and quantum confined structures, including their thermalization and extraction. Advances in retardation of thermalization mechanisms coupled with improved efficiency of extraction of hot carriers could lead to a new, fundamentally different class of photovoltaics, with efficiencies beyond the Shockley-Queisser limit.We will also address the challenge of radiation damage in these materials which is the main cause of performance deterioration for space photovoltaics. Impinging radiation introduces defects in the absorber, which act as non-radiative recombination sites for photogenerated carriers and therefore lead to a decrease in device-efficiency and therefore performance. The experimental techniques identified above can be used to effectively study defect sites. The planned correlative approach, together with capacity for time-resolved measurements in both cathodoluminescence and photoluminescence spectroscopy may provide new insight on defects and their effects in novel device structures.