Spectral and Luminescent Properties and Morphology of Self-Assembled Nanostructures of an Indotricarbocyanine Dye

Spectral and luminescent properties of an indotricarbocyanine dye are studied in solutions and after deposition on quartz or silicon substrates. It is found that the dye molecules self-assemble in aqueous EtOH solutions to form H*-aggregates. The absorption band of the H*-aggregates shows a hypsochromic shift of 192 nm (5291 cm–1) relative to the absorption maximum of dye monomers (706 nm) and has a full width at half maximum of 21 nm (797 cm–1). The morphology of the H*-aggregates of the indotricarbocyanine dye is studied for the first time. It is found that the aggregates are rod-like species ~10 nm high, 100 nm wide, and several micrometers long. H-aggregates with a fluorescence maximum at 560 nm and Stokes shift of 325 cm–1 in addition to non-fluorescent H*-aggregates form in aqueous EtOH solutions and are nanoparticles with a height of 1–3 nm and lateral dimensions of ~100 nm.