An organic thin film formed of molecules of at least one dye compound selected from the compounds represented by the following general formulae: ##STR1## wherein X is a hydrogen atom, a methyl group, or a halogen atom, R.sup.1 is an electron attractive group substituted with a hydrophobic group having 12 or more carbon atoms, Z is either=0 or=NR.sup.2, and R.sup.2 is an electron attractive group or an electron attractive group substituted with an organic group having 1 to 50 carbon atoms; andR--(DS) (III)where R is an organic hydrophobic group having terminated with two long chain alkyl groups or an organic hydrophobic group having a steroid carbon skeleton, and DS is a dyestuff group having a dye skeleton of tetracyanoquino dimethane, N, N'-dicyanoquinonediimine, N-cyanoquinoneimine, benzoquinone, pheylenediamine, tetrathiafulvalne, tetraselenavalene, ferrocene, phthalocyanine, or porphyrin.