Ultralong Organic Phosphorescence (UOP) has generated significant interest because of its applications in several areas such as photovoltaic cells, bioimaging and anticounterfeiting.1 The molecule of carbazole (Cz) is commonly used as a building block in organic materials for optoelectronic applications, acting as a light-absorbing, electron donor and emitting moiety. Cz and its derivatives display UOP at room temperature. While the processes behind UOP have been associated with the stabilisation of H-aggregates, recent experimental studies indicate the presence of impurities drives the mechanism keeping the excited states alive for a long time.2 In this talk, Dr Crespo Otero will discuss the mechanism behind light-induced processes in crystalline and impure Cz and some derivatives using embedding methods developed in our group.3,4 Dr Crespo Otero will revisit the role of aggregation and isomeric impurities on the excited state pathways and analyse the mechanisms for exciton, Dexter energy transfer and electron transport considering Marcus and Marcus–Levich–Jortner theories.5 The researchers' excited state mechanisms provide a plausible interpretation of the experimental results and support the formation of charge-separated states at the defect/host interface. They believe these results contribute to a better understanding of the factors that enhance the excited-state lifetimes in organic materials and the role of doping with organic molecules.
1 Kenry, C. Chen and B. Liu, Nat. Commun., 2019, 10, 2111.
2 C. Chen, Z. Chi, K. C. Chong, A. S. Batsanov, Z. Yang, Z. Mao, Z. Yang and B. Liu, Nat. Mater., 2021, 20, 175–180.
3 M. Rivera, M. Dommett, A. Sidat, W. Rahim and R. Crespo‐Otero, J. Comput. Chem., 2020, 41, 1045–1058.
4 M. Rivera, M. Dommett and R. Crespo-Otero, J. Chem. Theory Comput., 2019, 15, 2504–2516.
5 F. J. Hernández and R. Crespo-Otero, J. Mater. Chem. C, 2021, 9, 11882–11892.