From the visible to the near infrared: Revealing the optical response of J-aggregates thin films of cyanine dyes

J-aggregates thin films of cyanine dyes are very attractive organic nanomaterials formed by highly ordered assembly of supramolecular organic structures. These films show unique spectroscopic properties, making them promising candidates for integration into advanced electronic and photonic devices. Their spectra show very narrow resonances, resulting in spectral regions with high refractive index, comparable to semiconductors, and negative permittivity, similar to metals. This study focuses on the characterization of the optical properties of cyanine J-aggregates thin films, including refractive index and permittivity, in a wide spectral range from visible to near infrared wavelengths. Our findings highlight the potential of these structures for the development of sustainable photonic devices.