Abstract: A number of cyanine dyes and squarylium dyes have been investigeted. The relations between the photovoltaic effect and the dye structures, the mechanism of charge carriers photogeneration in organic materials have been studied. Marked effects of substitutive groups on the photovoltaic effects of donor-acceptor chromophore dyes were observed. We could find convincing indications that the quantum efficiencies vary regularly as the basicity of donor-heterocycle and the ionic potentials of molecules. Finally, the spectral range of squarylium dyes is discussed.