Electrochemical cross-linking of carbazole derivatives: a new route for bulk heterojunction based on semi-interpenetrating polymer networks^*

¹ Laboratoire de Physico-Chimie des Polymères et des Interfaces, Université de Cergy-Pontoise, 5 mail Gay-Lussac, 95031 Cergy-Pontoise Cedex, France
² Faculty of Chemical Technology, Kaunas University of Technology, Radvilenu Plentas 19, 3028 Kaunas, Lithuania

Corresponding author: Claude.Chevrot@chim.u-cergy.fr

Received: 25 July 2006
Accepted: 3 January 2007
Published online: 14 February 2007

Abstract

Electrochemical behaviors of different pendant carbazole based oligomers have been studied for the realization of electroactive tridimensional structures. 3-substitution by hydrazone functional groups onto the pendant carbazole moieties increases the electron donor properties of the electroactive units. Electrochemical oxidation of thin films of the oligomer precursors deposited onto electrode ensures the formation of a cross-linked structure by in situ anodic coupling with the formation of biscarbazole redox sites. When the electrochemical cross-linking of the oligomers is realized in the presence of the electron acceptor polyimide (perylene based), we form a semi-interpenetrating polymer network (semi-IPN) coated as a thin layer. The electrochemical behavior of the semi-IPN shows two reversible oxidations and two reversible reduction peaks indicating respectively the p-doping of the biscarbazole entity and the n-doping of the perylene one. The presence of hydrazone substituents modifies the electron donor properties of the semi-IPN and should influence the electron transfer properties from biscarbazole to perylene units in bulk heterojunction solar cells.