Development of new materials and structures for efficient organic solar cells fabricated with ionically and electrically conductive polymers

New materials and structures have been developed for efficient organic solar cells, dye-sensitized solar cells (DCSs) and organic thin-film solar cells (OPVs). In this paper, the authors discuss various strategies for achieving high photon-to-electricity conversion efficiency in these solar cells, focusing on nanostructured materials. In the case of DSCs, unlike TiO₂ nanoparticles, TiO₂ nanotubes with suitable dimensions are expected to function as efficient light scatterers as well as to give large surface areas for charge separation. A strategy for designing triarylamine-functionalized ruthenium dyes, which show high efficiency, is also proposed. Furthermore, OPVs based on donor/acceptor (D/A) block copolymers are discussed, focusing on the phase separation of donor and acceptor segments and their domain sizes.