In-Situ Growth-Studies of Metal Halide Perovskites for Tandem Solar Cells.

使用原位光致发光和UV-Vis测量与X射线衍射和成像技术相结合，我想研究金属卤化物钙钛矿的生长取决于所使用的衬底。该项目的目标是了解不同的衬底，特别是功能齐全的底部太阳能电池，如何影响随后沉积的钙钛矿层的成核，相发展和结晶路径（“生长”）。此外，将分析衬底的性质与钙钛矿的组成、择优取向、结构和形态的相互作用。这种理解将使我能够提出使用各种底部电池技术的串联太阳能电池中钙钛矿层的单独优化沉积工艺。特别是，我将比较单结太阳能电池（玻璃/铟锡氧化物（ITO）/空穴传输层（HTL）堆叠）的标准基板上的钙钛矿层的特性与其在底部电池上的特性分别基于Cu（In，Ga）Se 2（CIGS）吸收层和背结SI异质结器件。在所提出的工作计划的不同阶段，我将使用CIGS吸收层制备三种不同的沉积技术（分子束外延，热共蒸发，连续溅射/退火）以及不同的基板（刚性玻璃和柔性聚酰亚胺箔）。此外，我将改变所使用的HTL：溅射NiOx，原子层沉积NiOx和自组装单层（SAM）。虽然不同的沉积技术导致CIGS吸收剂层的粗糙度的强烈变化，并因此间接影响钙钛矿生长的衬底的形态，但不同HTL的使用直接影响钙钛矿层的成核。因此，在该项目期间要测试的主要假设是，底部电池的表面粗糙度以及HTL的表面性质将改变初始成核以及随后的生长和钙钛矿的整体性质。结合我在光伏应用多晶吸收材料的制造和表征方面的经验，以及所选主办机构提供的钙钛矿薄膜现场多模态分析的专业知识和设备，我的目标是分析钙钛矿层的生长与高时间-解决方案，能够发展所涉及的过程的基本理解，并给出详细的建议，顶部电池的制造。最后，我还将利用主办机构的实验装置来研究高效CIGS/钙钛矿和Si/钙钛矿叠层太阳能电池的退化机制。这样做，我将能够解开底部电池的性质对钙钛矿性质及其稳定性的相互作用。

Using a combination of in-situ photoluminescence and UV-Vis measurements together with X-ray diffraction and imaging techniques, I want to investigate the growth of metal halide perovskites depending on the substrate in use. The goal of the project is to understand how different substrates, in particular fully functional bottom solar cells, affect the nucleation, phase development, and crystallization path (the “growth”) of subsequently deposited perovskite layers. Furthermore, the interplay of the properties of the substrate and the composition, preferential orientation, structure, and morphology of the perovskite will be analyzed. This understanding will enable me to propose individually optimized deposition processes for the perovskite layers in tandem solar cells using various bottom cell technologies. In particular, I will compare the properties of the perovskite layer on standard substrates for single-junction solar cells (glass/indium tin oxide (ITO)/hole transport layer (HTL)-stacks) with its properties on bottom cells based on Cu(In,Ga)Se2 (CIGS) absorber layers and rear-junction SI-heterojunction devices respectively. In the different stages of the proposed work program, I will use CIGS absorber layers prepared by three different deposition techniques (molecular beam epitaxy, thermal co-evaporation, sequential sputtering/annealing) as well as on different substrates (rigid glass and flexible polyimide foil). Furthermore, I will vary the HTL used: sputtered NiOx, atomic layer deposited NiOx, and self-assembling monolayers (SAMs). While the different deposition techniques lead to strong variations in the roughness of the CIGS absorber layer, and therefore indirectly affect the morphology of the substrate of the perovskite growth, the use of different HTLs is directly affecting the nucleation of the perovskite layer. Consequently, the main hypothesis to be tested during this project is that the surface roughness of the bottom cell as well as the surface properties of the HTL will alter the initial nucleation as well as the following growth and the overall properties of the perovskite. Combining my experience in the fabrication and characterization of polycrystalline absorber materials for photovoltaic applications with the expertise and equipment for in-situ, multi-modal analysis of perovskite thin-films available at the chosen host organization, I aim to analyze the growth of the perovskite layer with a high time-resolution being able to develop a fundamental understanding of the involved processes and to give detailed suggestions for the top cell fabrication. Finally, I will also utilize the experimental setup at the host organization to investigate the degradation mechanisms of highly efficient CIGS/perovskite and Si/perovskite tandem solar cells. Doing so, I will be able to unravel the interplay of the properties of the bottom cells on the properties of the perovskite and its stability.