| 초록 |
We present variation of electronic properties of polythiophene and poly(p-phenylenevinylene) with the conjugation lengths. A variety of non-conjugated spacers were introduced into the conjugated chain in order to control the length. Modified extended Huckel band calculations show that the band gaps of the polymers linearly vary with the inverse of the conjugation length, except the case where m-phenylene units are introduced. It is found that methylene and silylene spacers are more effective to break conjugation along the chain than ether, thioether or m-phenylene spacers. Increasing the spacer length does not significantly affect the band gaps in the planar conformations. The short spacer length, however, is expected to induce torsion of the polymeric chain due to the repulsive interaction between conjugated segments around the spacers. |
