The Hitch-Hiker's Guide to Organic Semiconductors: Probing Structure–Function Relationship Using Time-Resolved EPR Spectroscopy

Organic semiconductors are increasingly important in our daily lives. Hence, gaining insights into their structure–function relationship is crucial to rationally design new materials. This is a multidisciplinary effort. Here, we present a series of examples ofhow applying time-resolved EPR (TREPR) spectroscopy to short-lived light-induced triplet states can contribute to our understanding of organic semiconductors and complement the picture gained by other methods. Aspects include the overallorientation and degree of ordering of polymer films on substrates, [1,2] the morphology and aggregation behaviour of polymers in solution, [3] the detailed mapping of electronic structure of polymers by investigating a series of building blocks with differentlengths, [4,5,6] the direct optical excitation of triplet states from the singlet ground state, completing our picture of potential triplet pathways, [7,8] exciton delocalisation modes by means of magnetophotoselection experiments, [2,9] and identifying the buildingblock resembling the electronic structure of the corresponding polymer [10]. Taken together, TREPR spectroscopy of triplet states provides highly relevant insight complementary to other methods, adding to our understanding of the structure–function relationship of organic semiconductors. Literature: [1] T. Biskup, M. Sommer, S. Rein, D. L. Meyer, M. Kohlstädt, U. Würfel, S. Weber, Angew. Chem. Int. Ed. 2015, 54, 7707.[2] D. L. Meyer, N. Schmidt-Meinzer, C. Matt, S. Rein, F. Lombeck, M. Sommer, T. Biskup, J. Phys. Chem. C, 2019, 123, 20017.[3] D. L. Meyer, R. Matsidik, S. Huettner, M. Sommer, T. Biskup, Phys. Chem. Chem. Phys. 2018, 20, 2716.[4] D. L. Meyer, R. Matsidik, M. Sommer, T. Biskup, Adv. Electron. Mater, 2018, 4, 1700385.[5] C. Matt, D. L. Meyer, F. Lombeck, M. Sommer, T. Biskup, Macromolecules, 2018, 51, 4341.[6] C. Matt, F. Lombeck, M. Sommer, T. Biskup, Polymers, 2019, 11, 870.[7] D. L. Meyer, F. Lombeck, S. Huettner, M. Sommer, T. Biskup, J. Phys. Chem. Lett 2017, 8, 1677.[8] C. Matt, D. L. Meyer, F. Lombeck, M. Sommer, T. Biskup, Mol. Phys., 2019, 117, 2645.[9] D. L. Meyer, R. Matsidik, D. Fazzi, M. Sommer, T. Biskup, J. Phys. Chem. Lett., 2018, 9, 7026.[10] C. Matt, R. Matsidik, D. L. Meyer, M. Schröder, M. Sommer, T. Biskup, Org. Electron., 2023, 117, 106790.