Charge Transfer Through Dithieno[2,3- a:3′,2′- c]phenazine: Effect of Substitution Pattern on the Optoelectronic Properties of Regioisomeric Luminophores.

Two series of regioisomeric luminophores that contained a dithieno[2,3- a:3′,2′- c]phenazine (DTP) unit as an electron acceptor have been designed and synthesized. To investigate the effect of substitution pattern on the optoelectronic properties of these luminophores, electron donors ( N, N-dihexylaniline or N, N-dihexyl-4-vinylaniline) were incorporated at the 2,5-, 8,11-, and 9,10-positions of the DTP unit. We found that the optoelectronic properties of the regioisomeric luminophores were greatly affected by the substitution pattern: functionalization at the 8,11-positions of the DTP unit was superior to the other two substitution patterns in extending the effective π-conjugation and strengthening the intramolecular charge-transfer interactions. Moreover, the insertion of vinyl groups between the DTP and N, N-dihexylaniline units narrowed the energy band-gap for isomers 4 and 5. However, hypsochromically shifted absorption and photoluminescence maxima were observed for isomeric luminophore 6, in which electron donors were substituted at the 2,5-positions of the DTP unit. These results should facilitate greater understanding of the structure-property relationships in regioisomeric semiconductors and present a new way to design optoelectronic materials with effective substitution patterns. [ABSTRACT FROM AUTHOR]