Organic Solar Cells for Outer Space with Improved Performance and Radiation Hardness by a High Throughput Artificial Intelligence Guided Approach

• Applicant: Professor Dr. Christoph J. Brabec
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 464963576

Communication technologies in space is a strongly expanding market. Satellites, typically in low earth orbits, are powered by photovoltaic panels whose critical figures of merit are weight and space consumption during transport, and radiation hardness in operation. Current technology relies on rigid Si modules, not exceeding a specific power of 1 W/g. In this project, we develop solar modules based on high performance organic photovoltaics. They will be flexible, reach a specific power above 20 W/g (> 5W/g for modules) and excellent radiation potentially enabling operational lifetimes up to 40 years in low earth orbits, bringing a decisive cost advantage in transportation.This goal is reached by a collaboration of expert groups in organic synthesis and high energy photophysics, photovoltaics technology, and closed cycle high throughput artificial intelligence guided optimization.We will deploy a large library of organic electron donor and acceptor materials with systematically varied chemical structure. We will study the detailed mechanisms of photodegradation under gamma radiation exposure of each material (radical formation, cross-linking, fragmentation and self-healing). Using state of the art machine learning techniques, namely kernel based nonlinear regression and interpretable neural networks, we will identify structural motifs causing photodegradation and others promoting self-healing. Based on this insight, we will synthesize optimized donor and acceptor materials with maximized radiation hardness that at the same time match requirements for high performance photovoltaics (low frontier orbital offset, low reorganization energy).Using these photoactive materials, we will build photovoltaic devices and estimate the operational lifetime under low earth orbit conditions (80% of initial power output). Furthermore, we will perform optimization of radiation-stable and light-transparent electrode coatings, charge-transport layers, adhesives and encapsulation that ensure stable operation of solar cells under the influence of ionizing radiation.Our consortium, composed of top performers in their respective fields, combines the full expertise needed to achieve the goals and counts on previous successful collaborations. The team of Pavel Troshin is renowned for design and synthesis of organic semiconductor materials and investigation of their degradation pathways caused by different stress factors. The group of Christoph Brabec is among the leaders in the field of high throughput device formulation and characterization in photovoltaics. The Solar Factory of the Future, directed by Christoph Brabec and managed by Hans Joachim Egelhaaf, currently holds the world record for efficiency in organic photovoltaic modules. This project will integrate their capacities in experimentation, technology and artificial intelligence, bringing their successful collaboration to a new level.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Science Foundation, until 3/2022
• Cooperation Partner: Professor Dr. Pavel A. Troshin, until 3/2022