Effect of nano-clay platelets on the J-aggregation of thiacyanine dye organized in Langmuir-Blodgett films: A spectroscopic investigation

In this paper we report the effect of the incorporation of nano-dimensional clay platelets, laponite, on the J-aggregation of a thiacyanine dye N,N′-dioctadecyl thiacyanine perchlorate (NK) assembled into Langmuir-Blodgett (LB) monolayers. π-A isotherms and atomic force microscopic studies confirm the successful incorporation of clay platelets into the Langmuir monolayer of NK. J-aggregates of NK remain present in LB films lifted at lower as well as higher surface pressures in the absence of laponite clay platelets. However, with the incorporation of clay platelets, J-aggregates are formed only in LB films lifted at higher surface pressure of 30 mN/m and totally absent in the films lifted at lower surface pressures of 10 and 15 mN/m. This may be due to the formation of nano-trapping level by overlapping of clay platelets at higher surface pressure. NK molecules may get squeezed to these nano-trapping to form J-aggregates.