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Molecular layer deposition (MLD) is a monomolecular-step growth method of organic tailored materials with designated molecular arrangements.MLD is achieved by utilizing selective chemical reactions or the electrostatic force between source molecules.MLD is usually performed in the vapor phase by introducing source molecule gases sequentially onto substrate surfaces.When MLD is performed in the liquid phase, it is called as Liquid-Phase MLD (LP-MLD).In the present talk, after the concept of MLD is reviewed, applications of MLD to sensitizing layers in oxide-semiconductor-based solar cells are proposed.[Sensitization by Polymer MQDs] Polymer multiple quantum dots (polymer MQDs), where three kinds of quantum dots with lengths of ~0.8, ~2 and ~3 nm are contained, were grown by MLD.It was found that the wide absorption spectra of the polymer MQDs are divided into three absorption bands of the individual quantum dots.The divided-spectra characteristics is expected to reduce the energy loss caused by the excess photon energy during light absorption processes, improving the energy conversion efficiency of the sensitized solar cells.[Sensitization by Multi-Dye-Stacked Structures] As the first step of the sensitization by multi-dye-stacked structures, two-dye-stacked structures of p-type dye (rose bengal (RB)) and n-type dye (crystal violet (CV)) were grown on a ZnO thin film by LP-MLD.In [ZnO/RB/CV] structure, electrons in RB were excited and injected into ZnO by green lights to generate photocurrents.Electrons in CV were injected into ZnO via RB by red lights.The photocurrent spectra of the [ZnO/RB/CV] structure were widened by the superposition of the spectra arising from RB and CV.The photocurrents were enhanced when the light exposure was carried out by guided lights in ZnO thin films, indicating the prospect of the waveguide-type sensitized solar cells.