ELECTRONIC-STRUCTURE OF POLY(PYRROLE THIOPHENE) COPOLYMERS - DESIGN OF POLYMERIC QUASI-ONE-DIMENSIONAL SUPERLATTICES

Ab initio band structure results of polypyrrole (PPY) and polythiophene (PTP) obtained with a double-zeta basis set are reported. The electronic density of states (DOS) of the various quasi-one-dimensional copolymers (superlattices) of the type (A(m)B(n))x (A = pyrrole; B = thiophene) have been calculated numerically within the ab initio SCF tight-binding approximation. These copolymers on the basis of the band positions of PPY and PTP are found to belong to the class of type II (staggered) superlattices. The trends in their electronic properties as a function of (i) composition (m/n), (ii) block sizes m and n, and (iii) arrangement of blocks in the copolymer chain are discussed.