Three-dimensional nanoscale organization of polymer solar cells

The performance of polymer solar cells (PSCs) strongly depends on the three-dimensional morphological organization of the compounds within the bulk heterojunction active layer. Donor and acceptor materials should form co-continuous networks with nanoscale phase separation to sustain effective dissociation of excitons into free electrons and holes at the donor/acceptor interface and to guarantee fast charge carrier transport from any place in the photoactive layer to the corresponding electrodes. Here, we describe applications of the technique of electron tomography to directly visualize with nanometre resolution and study in detail the 3D organization in the photoactive layers of PSCs, with the aim of identifying the critical morphology parameters contributing to high efficiency of bulk heterojunction systems. © 2009 The Royal Society of Chemistry