3,4-diaryl substituted polythiohene derivatives with various spacers

The research work presented here is based on the concept of introducing arylalkyl side chain on the 3,4 positions of thiophene. Most of the research work has been done on the 3-substituted polythiopens but there are only few reports on 3,4-disubstituted polythiophene derivatives. Here, instead of substituting the thiophene with alkyl group, arylalkyl (thienyl, aryl) groups has been used. It was found that such groups increase the conjugation in the side chain along with the main chain. To prove the concept several oligomers were also synthesized and characterized. To reduce the steric strain introduced by the disubstitution various spacers has been used. The effect of these spacers (bithiophene, ethynylene and vinylene)on the electronic properties were explored. It was found that these spacers were increasing the conjugation in the polymer and also serve as good candidate for reliving the steric strain. Several classes of polymers were synthesized and characterized by various methods and there photovoltaic behaviour were studied.