Study of substituent effect on band gaps of oligothiophene by using semi-empirical molecular orbital calculations

الملخص EN

The semi-empirical method at level PM3 has been used to obtain the optimized geometries and energy bands (Eg) for neutral and prorogated of 3- Substituted-oligothiophenes, the substituent’s were, H, CH3, OCH3, NH2, F, Cl and CN.

The geometry optimization yields planar conformation for all structures except in NH2-T14+ which was non-planar.

The Eg for protonated oligothiophenes all fall into the semi-conducting region.

The substituent effect on Eg was as the following sequence OCH3 > F > Cl > CH3 > H > CN > NH2.