Abstract:
LB films of dye molecules are prepared under biasing conditions. Conductive glass plates
are used to deposit LB films. Three-electrode configuration (Working, Counter (pt), and
standard calomel electrode (Ag/AgCl)) was used to apply a voltage to conductive glass
plates coupling to a potentiostate (Hokuto- Denko). Here the LB deposition instrument
acts as an electrochemical cell during the deposition of monolayers applying a fixed
voltage to conductive glass plate. It was found that absorbance spectra of di octadecyl
Merocyanine dye films on conductive glass plate consist of three peaks 510nm(dimmers)
540nm(monomers) and 580nm(J- aggregates). In the positive biasing condition, the
monomers are more abundant than dimmers and J- aggregates in the dye film. In the
negative biasing condition the dimmers and J - aggregates are more abundant than
monomers.
AFM Pictures shows that in the positive biasing condition the surface of dye films is 2D
where as in the negative biasing condition it is 3D due to formation of J-aggregates.
Surface Area Isotherms explain the interlocking of R- C l8 dye between two hydrocarbon
chains of C18-Mero-C18 dye molecules. . Interlocked molecules minimize the formation
of J- aggregates.
A photocurrent enhancement can be seen in the photo electrochemical cell when
formation of J- aggregates is controlled as the J - aggregates act as the trapping centres
for the charge carriers.
