Efficient triplet pair separation from intramolecular singlet fission in dibenzopentalene derivatives

In intramolecular SF (iSF), the strong coupling nature and confinement of diffusional separation of (1)(TT) limits the extraction and harnessing of triplet energy. In order to investigate the possible (1)(TT) separation and the role of molecular parameters on it, a series of iSF-capable dibenzopentalene derivatives (DBPs) have been synthesized and their photoinduced dynamics are monitored. iSF takes place in DBPs, accompanied by consecutive (1)(TT) separation in polycrystalline film with almost 100% yield. It is suggested the strong intermolecular coupling provided by the closely packing configuration in the film facilitates the disentanglement of correlated (1)(TT). Highly efficient triplet pair separation to yield free triplets makes one step forward for utilizing triplet energy from iSF materials for further optoelectronic applications.