Evidence of triplet–triplet interaction in crystalline sexithiophene

Abstract Optically detected magnetic resonance (ODMR) experiments are performed at room temperature on crystalline sexithiophene (6T) photoluminescence (PL). The observed spectra are interpreted in terms of microwave induced transitions between spin sublevels of triplet–triplet pairs states. These triplets are produced by intersystem crossing and their mutual annihilation which leads to delayed fluorescence (DF) is modulated by the high power microwave and enhance the PL process.