Interchain and correlation effects in oligothiophenes

In the present work we present ab initio 3–21 G* calculations on oligothiophene pairs. Electronic correlation has been accounted for at MP2 level. Electronic structures of a series of bithiophene and terthiophene pairs were investigated as function of the intermolecular distance, for neutral and charged systems. The results indicate that the stability of π-dimers increases with the oligomer size and that the intermolecular interaction can be strong enough to allow an intermolecular charge separation.