Optical and Resonant Non-Linear Optical Properties of J-Aggregates of Pseudoisocyanine Derivatives in Thin Solid Films

Abstract

The properties of colligative states of spontaneously aggregated polymethine dyes differ substantially from those of monomeric dye. Excellent examples of such self-organized molecular ensembles are J-aggregates of cyanine dyes. The J-aggregated state is now being considered for a number of non-cyanine dyes, the cyanine dye is still the most known and effective dye for J-aggregate formation (Wurthner, 2011). J-aggregates of cyanine dyes, first discovered by Jelley and Scheibe in 1936 (Jelley, 1936; Scheibe, 1936), have been studied for many years (Kobayashi, 1996). J-aggregates of cyanine dyes attract the attention of the researchers due to their interesting optical properties. J-aggregates are characterized by a strong absorption peak (J-peak) with narrow line widths which are bathochromically shifted relative to the absorption band of the monomeric dye. Their role as photographic sensitizers can hardly be overestimated (Tani, 1996; Trosken et al., 1995; Shapiro, 1994). Aggregates of dye molecules may be used to mimic light harvesting arrays and to prepare artificial photosynthetic systems (McDermott et al., 1995; Blankenship, 1995). Another development is the efficient electroluminescence revealed in single-layer light-emitting diodes based on electron-hole conducting polymers containing nano-crystalline phases of J-aggregates of cyanine dyes (Mal'tsev et al., 1999).