Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 18: Organic Electronics and Photovoltaics I

CPP 18.8: Vortrag

Dienstag, 19. März 2024, 11:45–12:00, H 0110

Charge-carrier photogeneration in single-component organic semiconductors via low excitation power triplet-triplet annihilation — •Andreas Sperlich¹, Andrei Stankevych², Rishabh Saxena², Jeannine Grüne^1,3, Stavros Athanasopoulos⁴, Prakhar Sahay⁵, Wolfgang Brütting⁵, Vladimir Dyakonov¹, Heinz Bässler⁶, Anna Köhler^2,6, and Andrey Kadashchuk² — ¹Experimental Physics 6, University of Würzburg, 97074 Würzburg — ²Soft Matter Optoelectronics and Bavarian Polymer Institute, University of Bayreuth, 95448 Bayreuth — ³Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK — ⁴Departamento de Física, Universidad Carlos III de Madrid, 28911 Madrid, Spain — ⁵Institute of Physics, University of Augsburg, 86159 Augsburg — ⁶Bayreuth Institute of Macromolecular Research, University of Bayreuth, 95448 Bayreuth

We investigate the carbazole-based material mCBP-CN, a typical host for TADF OLEDs. Our findings challenge established beliefs by demonstrating efficient charge-carrier generation near the absorption edge. Light-induced ESR and luminescence studies at low temperatures unveil slow carrier accumulation and recombination, indicating shallow trapping. Persistent signals in both techniques suggest a common origin. Photocurrent measurements support bimolecular charge generation, emphasizing the role of triplet-triplet annihilation in creating charge pairs. This work highlights unconventional mechanisms in organic semiconductors, relevant beyond OLEDs, but also for long-persistent luminescence, organic photovoltaics, and photocatalysis.

Keywords: Triplet-Triplet Annihilation; Photoluminescence Spectroscopy; Photo Current; ESR