Mater. Res. Soc. Symp. Proc. Vol. 1435 © 2012 Materials Research Society DOI: 10.1557/opl.2012. Transparent Conductive Oxide Less Flexible Dye-sensitized Solar Cells with Flat and Cylinder Shapes Jun Usagawa, Byung-wook Park, Yuhei Ogomi, Shyam S. Pandey, and Shuzi Hayase Kyushu Institute of Technology, 2-4, Hibikino, Wakamatsu-ku, Kitakyushu 808-0196 Japan ABSTRACT Transparent conductive oxide less flexible dye-sensitized solar cells (TCO-less DSC) with flat and cylinder shapes are reported. The cell consists of a plastic cover, a flexible titania/dye sheet back contacted with a metal mesh sheet, a gel electrolyte sheet, and Pt layer on a Ti sheet. How to increase the efficiency were discussed. We concluded that making a titania/dye layer on a metal mesh sheet thinner and using a thinner electrolyte layer were effective for increasing the efficiency. A flat TCO-less DSC with 6.1 % efficiency and a cylindrical TCO-less DSC with 5.1 % efficiency are reported. INTRODUCTION The certified efficiency for dye sensitized solar cell (DSCs) reached 11 % [1,2]. DSCs usually consist of transparent conductive oxide glasses (TCO-glass). TCO-glasses are still expensive now and restrict solar cell shapes. We focused on structures and fabrication process of transparent conductive oxide less DSCs (TCO-less DSCs), where porous metal electrodes are fabricated at the back side of titania/dye layers as back-contact structures as shown in Fig.1. [3- 7] Glass only Porous Metal Ti sheet Glass with TCO Ti sheet TCO‐less DSC (back contact) DSC with TCO Light Light TCO Iodide/i odine Charge generation sheet Fig. 1 TCO‐less DSC with back contact electrodes and conventional DSC with TCO‐ layers We have already reported flat type, fiber type, and cylinder type dye sensitized solar cells [8- 12]. In this report, how to optimize the structure for each cell is discussed. 1695