Photoelectrochemical properties of Langmuir–Blodgett films of two squaraine derivatives

Abstract

Photocurrent generation from Langmuir–Blodgett (LB) overlays on indium tin oxide (ITO) electrodes, where the active components are 2,4-bis[4-(dibutylamino)-2-hydroxyphenyl]squaraine (1) and the unsubstituted analogue, 2,4-bis[4-(dibutylamino)phenyl]squaraine (2), have been investigated. Dye 1 shows improved behaviour compared with the latter and differences in performance are attributed to a modified aggregate structure, this being indicated by variations in the LB film spectra. The photocurrent generation is enhanced by the presence of electron acceptors, e.g. N,N′-dimethyl-4,4′-bipyridinium diiodide (MV²⁺), but quenched by electron donors, e.g. hydroquinone (HQ). The concentration dependence is reported.