Bornschlegl Andreas J, Duchstein Patrick, Wu Jianchang, Rocha-Ortiz Juan S, Caicedo-Reina Mauricio, Ortiz Alejandro, Insuasty Braulio, Zahn Dirk, Lüer Larry, Brabec Christoph J
Institute of Materials for Electronics and Energy Technology (i-MEET), Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Martensstraße 7, 91058 Erlangen, Germany.
Chair for Theoretical Chemistry/Computer Chemistry Center (CCC), Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Nägelsbachstraße 25, 91052 Erlangen, Germany.
J Am Chem Soc. 2025 Jan 15;147(2):1957-1967. doi: 10.1021/jacs.4c14824. Epub 2025 Jan 3.
Emerging photovoltaics for outer space applications are one of the many examples where radiation hard molecular semiconductors are essential. However, due to a lack of general design principles, their resilience against extra-terrestrial high-energy radiation can currently not be predicted. In this work, the discovery of radiation hard materials is accelerated by combining the strengths of high-throughput, lab automation and machine learning. This way, a large material library of more than 130 organic hole transport materials is automatically processed, degraded, and measured. The materials are degraded under ultraviolet-C (UVC) light in a nitrogen atmosphere, serving as the conditions for electromagnetic radiation hardness tests. A value closely related to the differential quantum yield for photodegradation is extracted from the evolution of the UV-visible (UV-vis) spectra over time and used as a stability target. Following this procedure, a stability ranking spanning over 3 orders of magnitude was obtained. Combining Gaussian Process Regression based on predictors from structural fingerprints and manual filtering of the materials by features, structure-stability relations for UVC stable materials could be found: Fused aromatic ring clusters are beneficial, whereas thiophene, methoxy and vinylene groups are detrimental. Comparing the UV-vis spectra of the degraded material in film and solution, bond cleavage could be made out as the leading degradation mechanism. Even though UVC light can in principle break most organic bonds, the stable materials are able to distribute and dissipate the energy well enough so that the chemical structures remain stable. The established predictive model quantifies the effect of specific molecular features on UVC stability, allowing chemists to consider UVC stability in their molecular design strategy. In the future, a larger data set will allow to inversely design molecular semiconductors which show high performance and radiation hardness at the same time.
用于外层空间应用的新兴光伏技术是辐射抗性分子半导体至关重要的众多例子之一。然而，由于缺乏通用的设计原则，目前无法预测它们对外层空间高能辐射的抗性。在这项工作中，通过结合高通量、实验室自动化和机器学习的优势，加速了辐射抗性材料的发现。通过这种方式，一个包含130多种有机空穴传输材料的大型材料库被自动处理、降解和测量。这些材料在氮气气氛中的紫外-C（UVC）光下进行降解，以此作为电磁辐射硬度测试的条件。从紫外-可见（UV-vis）光谱随时间的变化中提取出一个与光降解微分量子产率密切相关的值，并将其用作稳定性指标。按照这个程序，获得了跨越3个数量级的稳定性排名。结合基于结构指纹预测器的高斯过程回归以及按特征对材料进行人工筛选，可以找到UVC稳定材料的结构-稳定性关系：稠合芳香环簇是有益的，而噻吩、甲氧基和亚乙烯基是有害的。通过比较薄膜和溶液中降解材料的UV-vis光谱，可以确定键断裂是主要的降解机制。尽管原则上UVC光可以破坏大多数有机键，但稳定的材料能够很好地分散和耗散能量，从而使化学结构保持稳定。所建立的预测模型量化了特定分子特征对UVC稳定性的影响，使化学家能够在分子设计策略中考虑UVC稳定性。未来，更大的数据集将允许反向设计同时具有高性能和辐射抗性的分子半导体。
