Influence of transfer promoters on the deposition and wettability characteristics of copper tetra-tert-butyl phthalocyanine Langmuir-Blodgett films

This study investigated the influence of three transfer promoters on the de position and wettability characteristics of copper tetra-tert-butyl phthalo cyanine (CuTTBPc) Langmuir-Blodgett (L-B) films. With the addition of trans fer promoters, such as stearyl alcohol, stearamide, and arachidic acid, two transitions corresponding to monolayer collapse were observed in the surfa ce pressure-area isotherms of mixed CuTTBPc/transfer promoter monolayers at the air/water interface. Nevertheless, the expected enhanced stability of a CuTTBPc monolayer in the presence of transfer promoters did not reflect i n the monolayer area relaxation curves obtained at constant surface pressur es. The transfer ratio for the deposition of a CuTTBPc L-B film on a glass substrate was close to one, and thus the addition of transfer promoters sho wed little improvement in the deposition. On a gold-coated glass substrate, however, the deposition of a CuTTBPc L-B film was considerably improved by the existence of arachidic acid. Surprisingly, the deposition was not impr oved with the addition of stearyl alcohol or stearamide. Moreover, the pres ence of transfer promoters did not show significant influence on the wettab ility characteristics of the mixed CuTTBPc/transfer promoter L-B films on g lass or gold-coated glass substrates except for the case of arachidic acid. (C) 2001 Elsevier Science B.V. All rights reserved.