Multiexcitonic Triplet Pair Generation in Oligoacene Dendrimers as Amorphous Solid-state Miniatures.

Singlet fission in organic semiconducting materials has attracted great attention for the potential application in photovoltaic devices as the exciton multiplication process effectively compensates for thermal energy losses. Research interests have been concentrated on identifying working mechanisms of coherent SF processes in crystalline solids as ultrafast SF is hailed for efficient multiexciton generation. However, as long lifetime of the intermediate state, multiexcitonic triplet pair, in amorphous solids facilitates the decorrelation process for triplet exciton extractions, a precise examination of incoherent SF processes is demanded in delicate model systems to represent heterogeneous structures. By introducing dendritic structures, heterogeneous coupling and energetics for SF were developed in our oligoacene oligomers, which mimic complicated SF dynamics in amorphous solids. SF dynamics in dendritic structures was thoroughly investigated by time-resolved spectroscopic techniques and quantum chemical calculations in respect of the relative orientation/distance between chromophores and though-bond/-space interactions.