A Donor–Acceptor Polymer with a Peculiar Negative-Charge-“Trapping” Characteristic


  • We are grateful to Prof. Chiara Castiglioni and Prof. Giuseppe Zerbi for their help in IR spectra interpretation and for stimulating discussions, and to Dr. S. Schiavon and Dr. G. Zotti for their contribution in performing and understanding the electrochemical measurements. This work was supported by CNR within the framework of the Progetto Finalizzato “Materiali Speciali per Tecnologie Avanzate II” and by Italian Ministry of Scientific Research (MURST 2000).


Voltammetric and spectrophotometric measurements of poly(3,3″-dipentoxy-3′-dicyanoethenyl-2,2′:5′,2″-terthiophene) (polyCN) films, in connection with other experimental evidence, reveal a normal oxidative, but a peculiar reductive behavior consisting of trapping of the negative charge during the cathodic scan. Another interesting property of polyCN films is the tendency to form strong intramolecular and intermolecular associations, probably charge-transfer (CT) complexes. These properties could account for the fact that the photovoltaic performance does not improve when polyCN is blended with a polythiophene donor.