Liquid phthalocyanine and fullerene derivative monomers were synthesized, which can be cationically polymerized either thermally or by light and are suitable for preparing complex solar cell structures, obtainable only by organic vacuum deposition till now. A sandwich solar cell with a bulk heterojunction layer between single layers was shown to produce higher currents and voltages than either pure bilayer or pure bulk heterojunction. The proposed in situ polymerization method can be applied to a variety of active layers for preparation of solution-processed solar cells. (C) 2010 Elsevier B.V. All rights reserved.