Delayed Fluorescence of Zinc Porphyrin in Poly(vinyl alcohol) Film

Abstract The delayed fluorescence was observed at room temperature with tetrakis(4-sulfophenyl)porphinatozinc (ZnTPPS4) dyed on poly(vinyl alcohol) (PVA) film. In the film, the T-T annihilation is prohibited since any two molecules in the excited triplet can not encounter during their lifetime. Three types of luminescence emission were observed; fluorescence (S1→S0), phosphorescence (T1→S0) and delayed fluorescence (T1\ightsquigarrowS1→S0). The delayed fluorescence can be detected only at elevated temperatures where thermal activation from the lowest excited triplet can repopulate the lowest excited singlet.