Aydemir, Murat2026-03-262026-03-2620190170-08391436-244910.1007/s00289-019-02729-82-s2.0-85062045141https://doi.org/10.1007/s00289-019-02729-8https://hdl.handle.net/20.500.14901/2367Aydemir, Murat/0000-0002-8359-5649In this work, the complex excited state dynamics of a sky-blue emitting co-polymer {poly-[9,9 '-dioctylfluorene-co-bis-N,N '-(4-butylphenyl)-bis-N,N '-phenyl-1,4-phenylenediamine]} is determined, using a time-resolved gated spectroscopy method, which helps to investigate the origin of delayed fluorescence in thin film. It is clearly shown that delayed fluorescence arises from triplet-triplet annihilation mechanism, which opens an indirect pathway to generate singlet excitons. Experimentally, the delayed fluorescence yield varies from 20% at room temperature to 46 +/- 2% at 20 K, suggesting that an alternative triplet harvesting mechanism is operative to convert the triplet into emissive singlet states.eninfo:eu-repo/semantics/closedAccessArticle