Charge-carrier photogeneration in single-component organic carbazole-based semiconductors via low excitation power triplet-triplet annihilation

• DOI: 10.1103/physrevapplied.20.064029
• Publication Date: 2023-12-15T15:02:31Z
• Authors: Andrei Stankevych; Rishabh Saxena; Jeannine Grüne; Sebastian Lulei; Andreas Sperlich; Stavros Athanasop...; Alexander Vakhnin; Prakhar Sahay; Wolfgang Brütting; Vladimir Dyakonov; Heinz Bässler; Anna Köhler; Andrey Kadashchuk
• Keywords: Photocurrent; Organic semiconductor; Charge carrier; Annihilation; Carbazole

This work demonstrates that triplet-triplet annihilation (TTA) is the predominant mechanism of intrinsic photogeneration charge-carrier pairs via autoionization, in a single-component disordered organic system with no heavy atoms. The findings challenge established beliefs by revealing efficient carrier generation TTA upon excitation near absorption edge. Photocurrent measurements, optical spectroscopy, and spin-sensitive techniques support this model bimolecular charge generation. Such mechanisms semiconductors are relevant not just for OLEDs, but also long-persistent luminescence, photovoltaics, potentially photocatalytic water splitting.