Molecular stacking of oriented porphyrin J-aggregates probed by dichroic electrochromism

Summary form only given.Molecular J-aggregates are attracting the interest of many scientists as photoactive materials based on molecular excitons. The excitonic transition of the J-aggregates has a large oscillator strength characterized by one-dimensional systems, which results in an enhanced optical nonlinearity. Previously, we developed a vertical spin-coating method to prepare oriented J-aggregates dispersed in polyvinylalcohol (PVA) films. The new method enabled us to investigate detailed structure of J-aggregates. In the present paper, the molecular stacking and the number of molecules in a one-dimensional J-aggregate were determined by means of dichroic electrochromism (DCE). The dye molecule studied is tetraphenyl porphyrin sulfonic acid, information about which may offer a very important clue to the light-harvesting mechanism in a system of antenna chlorophyll.