Crystalline structure determination for poly(4,4′-dialkyl-2,2′-bithiophenes)

The crystalline structure of poly(4,4′-dialkyl-2,2′-bithiophenes) (PDABTs), the regioregular pure ‘head to head, tail to tail’ coupled analogues of poly(3-alkylthiophenes) (P3ATs) has been determined by use of X-ray diffraction and computer modelling. Three types of samples have been considered, namely, those containing n-hexyl, n-octyl and n-decyl groups. The main conclusion of this work is that the crystalline structure of PDABTs can be explained by the orthorhombic unit cell, but the polymer chains are twisted to a higher degree than in the case of P3ATs. The influence of stretching and doping processes on the structural properties of PDABTs has also been investigated.