An electronic device containing a polythiophene prepared by a metal
halide-mediated coupling polymerization in an appropriate solvent, and
which polythiophene is comprised of at least one monomer unit selected
from the group consisting of 2,5-thienylene (or 2,5-thiophenediyl) (I),
2,5-thienylene (or 2,5-thiophenediyl) (II), and a divalent linkage D
##STR00001## wherein, for example, A is alkyl, alkoxy or derivatives
thereof; B is a hydrogen atom, a small substituent like alkyl or alkoxy.