Pure and mixed evaporated dye layers of a merocyanine: Structural and spectroscopic characterization

Layers of the merocyanine 3-ethyl-5-[2-(3-ethyl-2-benzothiazolidene)-ethyl(-idene)]-rhodanine (MC1) which were pure or mixed with metal halides or metal oxides were prepared by evaporation on glass substrates. Coupled structural and spectroscopic investigations of macroscopic dye crystals and microcrystals in the dye films reveal the formation of a triclinic modification with weak fluorescence. With increasing substrate temperature an increasing portion of strong emitting monoclinic microcrystals is formed. Co-evaporation of MC1 with inorganic substances (metal halides, metal oxides) restricts crystallization depending on dye concentration and kind of matrix.