Layer deposition system for perovskite solar cells (Partial financing)

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The group Physics of Solar Energy Conversion of Prof. Goldschmidt's conducts research into the fundamental physical processes in solar cells. The findings are used to derive conceptually new solar cell structures and advance existing concepts. Here, the material class of perovskites, especially organic-inorganic metal halide perovskites, is very attractive. The high absorptance allows almost complete absorption of sunlight with thin layers and the tolerance to crystal defects enables the use of simple processes compared to other semiconductor technologies. However, several challenges stand in the way of a broad application of perovskites in photovoltaics: Stability must be guaranteed for more than 25 years and high efficiencies must be achieved with materials and processes that are sufficiently available even in a terawatt-scale photovoltaic industry and do not generate other environmental problems (e.g. toxicity). To meet these challenges, a deep understanding of the physical processes within the perovskites and at the interfaces of the solar cell is an indispensable prerequisite. The thin-film deposition system applied for here is intended to produce perovskite solar cells under controlled conditions with a high degree of reproducibility in order to enable a rigorous investigation of their physical properties. The setup combines wet chemical methods of layer deposition (spin coating and blade coating) with the vacuum-based methods of evaporation, sputtering and atomic layer deposition (ALD). Due to the variety of methods, different types of solar cells can be realised. In particular it is planned to produce all-perovskite tandem solar cells, which promise particularly high efficiencies, and solar cells with graphite electrodes, which are characterised by particularly high stability. The configuration of the system minimises unwanted interferences and allows for efficiently producing a sufficient number of samples for good statistics. Key features are (i) working in multiple glove boxes, each with a separate nitrogen atmosphere (ii) laminar flow functionality at the site of the wet chemical processes (iii) load lock between sputtering and evaporation chambers and (iv) a combinatorial shutter for partial coverage of the substrate during certain evaporation processes. The opto-electronic properties of the samples produced in the layer deposition system are then characterised in the Goldschmidt AG. A comprehensive, excellent infrastructure is currently being set up for this purpose. Further investigations of opto-electronic and structural properties are planned within the department and in national and international ongoing and future projects.