Energetic alignment of buried junctions and tailored interfaces in photoelectrochemical multi-junction devices

本项目旨在阐明光电化学多结器件异质界面的电子结构和能带排列。理解电解液附近光电化学器件相对于其相对能量位置的能带图以及电子表面态的形成将有助于理解整个器件的效率限制因素。吸收层与化学钝化层、电子钝化层以及共催化剂的耦合将被系统地研究，主要是通过真空中与光电子能谱相结合的电化学方法。密度泛函理论将允许对实验数据进行深入解释，最终提供关于能量排列起源的原子论观点。由于光吸收、电荷分离和转移以及多电子催化的基本过程是高度相关的，我们将重点介绍两种已经显示出高效率但仍未达到物理极限的水分离多结器件：硅基多结以及基于III-V化合物半导体的串联电池。在此确定的改变异质界面电子耦合的路线也将与其他合作伙伴密切合作，在操作条件下进行研究和评估。从研究联盟的长远角度来看，该项目将提供可以转移到其他高效多结系统的通用研究方法。

This project seeks to elucidate the electronic structure and energetic band alignment at the hetero-interfaces of photoelectrochemical multi-junction devices. Comprehension of the band energy diagrams of photoelectrochemical devices in the vicinity of the electrolyte with respect to their relative energetic position as well as the formation of electronic surface states will help to understand efficiency-limiting factors of the overall device. The coupling of absorbers to chemical and electronic passivation layers as well as co-catalysts will be systematically studied, primarily by electrochemical methods coupled in-vacuo to photoelectron spectroscopy. Density functional theory will allow an in-depth interpretation of experimental data, finally providing an atomistic view on the origin of energetic alignments. As the elementary processes of light absorption, charge-separation and -transfer, as well as multi-electron catalysis are highly interrelated, we will focus on two established water splitting multi-junction devices that have already demonstrated high efficiencies, but still have not reached the physical limits: silicon-based multi-junction as well as III-V compound semiconductor-based tandem cells. The hereby identified routes to modify the electronic coupling of the hetero-interfaces will, in close cooperation with the other partners, also be studied and evaluated under operating conditions. For the long-term perspective of the Research Consortium, this project will provide generalised research approaches that can be transferred to other high-efficiency multi-junction systems.