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 deposition and wettability characteristics of copper tetra-tert-butyl phthalocyanine (CuTTBPc) Langmuir-Blodgett (L-B) films. With the addition of transfer promoters, such as stearyl alcohol, stearamide, and arachidic acid, two transitions corresponding to monolayer collapse were observed in the surface 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 in the monolayer area relaxation curves obtained at constant surface pressures. 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 showed 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 improved with the addition of stearyl alcohol or stearamide. Moreover, the presence of transfer promoters did not show significant influence on the wettability characteristics of the mixed CuTTBPc/transfer promoter L-B films on glass or gold-coated glass substrates except for the case of arachidic acid.