In this paper, a new type of flexible working electrode, TiO2/CuI/Cu, is reported, in which the p-n junction of TiO2-CuI is introduced into dye sensitized solar cells (DSSCs) for the first time. The devices give a high conversion efficiency of up to 4.73% under 1 sun illumination. The excellent performance is ascribed to the existence of the p-n junction, which forms a single directional pathway for electron transport which benefits the charge separation, and improves the efficiency of the flexible solar cells as a result.