ICRC 2024 - Session 1

PD Dr. Emanuel Ionescu
Fraunhofer IWKS 

Solution processed Perovskite Solar Cells (PSCs) are already leading the pack of leading photovoltaic technologies competing with inorganic thin-film solar cells and mainstream multi-crystalline silicon cells in terms of efficiency and production costs. However, there are a large number of materials challenges both in terms of composition (stability, toxicity, etc.) and device applications (endurance under in-operando conditions, hydrolysis, etc.) that still need to be addressed to realize the device potential of this promising class of materials. Besides greener approaches (lead-free compositions, non-toxic solvent, etc.), the desired maturity of PSC technology demands a judicious reduction of parametric space of materials synthesis and selection of materials based on their limited stress-tolerance (e.g., ion migration) and resilience under processing and operational conditions. In this context, the main objectives of greener or alternative processing are to solve two major issues associated with the implementation of PSCs; toxicity and stability. Most of the PSC fabrication is done utilizing dimethyl formamide (DMF) as the solvent that is listed among “Substances of very high concern” by the European Chemical Agency and its use may represent a potential hurdle for the future industrial production of the perovskite-based PV technology. Another major toxic component is its metal (Pb) part. The toxicity of the water-soluble source of lead remains as another limitation in outdoor application of these types of solar cells. In general, replacing Pb with other less or non-toxic metals remains a challenge.

This talk will address the challenges associated with alternative and greener processing of photon harvesting materials.

The currently prevalent productive system is based on a “take–make–dispose” logic, which assumes that energy and resources are unlimited, available, and easy to dispose of. This linear economy approach is no longer sustainable in the global context, due to the sharply increasing exploitation of non-renewable resources and the consequent growing degradation of our planet. A viable alternative is the one proposed and redesigned in a coherent context by Ellen MacArthur who, since the early 2000s, coined the expression “circular economy” as a possible answer to the limited availability of necessary resources, both materials and energy ones. The pivotal role of chemistry in this context is well acknowledged, but it is typically explained as the role of molecular chemistry through the concept of “circulating molecules”, that is, re-using and recycling existing molecules that are the building blocks of the end-consumer products approaching the end of their lives. However, inorganic non-molecular materials, such as ceramics, metals, alloys, semi-conductors, etc. constitute the majority of solid materials and play key roles as construction materials, and for industries such as automotive, microelectronics, lighting or as materials for regenerative and sustainable energy conversion and storage. Therefore, circular approaches for these classes of materials are of high importance. Specifically relevant is inorganic chemistry, encompassing both molecular and materials/solid state aspects.

To count as “sustainable,” materials nowadays must fulfill many aspects. We want them to be safe for people and the planet, free of criticality and conflict, fully circular in the global economy, and carbon neutral. Of course, we still want them to have high performance and enable long product lifetime. Hardly can all these requests be fulfilled equally and free of cost, but they need to be addressed. Therefore, evaluating the full sustainability potential of new materials requires a broad knowledge and expertise in various assessment methods, combined with the courage to prioritize sustainability dimensions depending on the anticipated application of the material. This talk presents the current status of assessment methods for critical raw materials, circularity, and carbon footprint of materials, focusing on metals and raw materials. It further shows the need for improved data collection, essential fields for scientific collaboration, and options for integrating material sustainability into material selection and development procedures.

A sustainable material implies that in addition to its functional performance, the environmental performance needs to be assessed from a multi-criteria perspective. This is especially relevant for the development of innovative and circular materials at early development stages when design freedom is still high. Prospective life cycle assessment (p-LCA) supports the early-stage assessment of environmental impacts. P-LCA uses upscaling frameworks and scenario approaches to determine the future environmental performance of innovative technologies. Recent p-LCA frameworks have also considered material-specific aspects: the UpFunMatLCA proposes a systematic upscaling scheme for material development distinguishing between upscaling mechanisms for process learning, material learnin  g, and external developments. This research applies the UpFunMatLCA to a case study on the production of biobased binders and performs a p-LCA from lab/pilot to early fab scale. We demonstrate how the upscaling scheme can be integrated into the material development process and analyze the effects of the different upscaling mechanisms on future environmental performances. The results indicate a very high potential for environmental improvements from lab to early fab scale, driven by process learning and by external developments. We critically discuss the feasibility of systematic upscaling and outline specifics for the assessment of recycled and more circular materials.

In the present talk, our recent activities related to the development of novel ceramic nanocomposites to be operated at high temperatures as well as in ultra-harsh environmental conditions will be highlighted and critically discussed. Typically, single-source precursors based on silicon-based polymers with tailor made molecular structure are used to preparatively access ceramic nanocomposite formulations showing excellent robustness against decomposition, devitrification, oxidation/corrosion and/or creep, which may be used as high-potential structural materials for internal combustion engines or in chemical plants. Additionally, the developed materials possess specific functionalities such as chemiresistive, temperature or strain sensing capability. The talk will exemplarily introduce materials developments related to e.g., novel ultrahigh-temperature ceramic coatings or piezoresistive strain sensors and will elaborate on the perspectives of precursor-based ceramic nanocomposites as highly promising functional materials for operation in extreme conditions.