Temperature and concentration dependence of J-aggregate of a cyanine dye in a Laponite film fabricated by Langmuir–Blodgett technique

• Formation of Langmuir and LB film of a thiacyanine derivative NK.
• NK forms J-aggregate in LB film.
• Conditions for the formation of NK J-aggregate in hybrid LB films were demonstrated.
• J-aggregated films of NK were SHG active although intrinsically NK was SHG inactive.
• Mechanical stability of the hybrid NK LB film was better than pure NK LB film.

In this communication, we report the temperature and concentration dependence of J-aggregate of a cyanine dye N, N′-dioctadecylthiacyanine perchlorate (NK) in the Laponite film fabricated by Langmuir–Blodgett technique. Surface pressure area per molecule isotherm revealed the formation of stable Langmuir monolayer at the air–water interface. Spectroscopic characterization confirmed the formation of J-aggregates in the NK LB film without Laponite. In the hybrid film, J-aggregate forms at lower Laponite concentration (1 ppm), higher deposited surface pressure and at lower subphase temperature. Both the J-aggregated films were found to be optical second harmonic generation (SHG) active and mechanically very stable, although intrinsically NK is SHG inactive.