Sub-picosecond time-resolved photoluminescence in substituted thiophenes

The emission properties of tetra and hexa methyl sulphanyl (SMe) substituted sexithiophenes have been studied in solution form using time-resolved up-conversion photoluminescence technique. The SMe substituents have an electron donating effect which compensates for the loss of π-electron conjugation caused by the twisted conformation of the molecular geometry. Enhanced conjugation however does not lead to long recombination time due to the heavy atom effect, which increases the nonradiative decay rate.