Photoluminescence quenching in oligothiophene single crystal

A single crystal of stereo-regularly substituted dihexylsexithiophene (DH6T) was synthesized. The transient photoluminescence decay curve of the crystal was non-exponential as in amorphous polythiophene. This non-exponential decay curve could be successfully described by stretched exponential decay kinetics, which represent the exciton diffusing to the one-dimensionally dispersed quenching centers. The generation of radical species by photoirradiation was confirmed by light-induced ESR measurement. It is probable that these radical species act as the quenching center for photoluminescent excitons.