TRANSIENT PHOTOCONDUCTIVITY OF ACCEPTOR-SUBSTITUTED POLY(3-BUTYLTHIOPHENE)

We have studied acceptor-substituted poly(3-butylthiophene) in an atte mpt to examine the role of acceptor molecules as intrinsic charge trap s under light excitations by measuring the transient photoconductivity response following pulse excitation. The specially synthesized accept or molecule is a chemically prepared high electron affinity (HEA) mono mer, 1-(4-nitrophenyl)-2-( 3-thienyl)ethene. In the copolymers prepare d with this acceptor monomer we have observed simultaneous decrease of the sub-nanosecond photoconductivity and increase of the slow compone nt (t > 10 ns) photoconductivity, with increasing HEA group concentrat ion in the substituted poly(butylthiophene)s. The slow component is at tributed to a bimolecular recombination process.