Nanostructured Materials Formed by Molecular Layer Deposition for Enhanced Solar Energy Utilization with Optical Waveguides

Abstract

We propose a waveguide-type sensitized photovoltaic device, where the porous semiconductors in a conventional dye-sensitized solar cell are replaced with flat thin-film semiconductors of high crystalline quality and high electron mobility. Although the light-absorbing layer on the semiconductor surface is very thin, sufficient light absorption is available in the guided light beam configurations. The light-absorbing layer is fabricated by molecular layer deposition (MLD), which achieves molecule-by-molecule polymer wire growth with designated molecular arrangements. MLD also forms self-assembled molecular structures utilizing electrostatic force. We demonstrated that MLD constructs polymer wires with multiple quantum dots, which are expected as efficient and robust light-absorbing layers. Measurements in the guided light beam configurations revealed that sensitized spectral regions of photocurrents are widened by self-assembled double layers of p-type and n-type dye molecules formed on ZnO thin films by liquid-phase MLD. Integration of the waveguide type devices into light beam collecting films will provide resource-saving flexible solar energy conversion systems.