In p-type dye-sensitized solar cells (p-DSSCs), NiO is the most commonly used p-type semiconductor [1]. Considering the drawbacks of NiO, alternative p-type semiconductors with better optical transparency, lower VB edge position and higher hole mobility are desired for p-DSSCs [2]. The cuprous oxide (Cu2O) is a natively p-type semiconductor with a direct band gap of about 1.9–2.2 eV [3]. Non-toxic nature, the stability, natural abundance, low cost production, good electrical properties and a good absorption coefficient for visible light prompted to investigate the cuprous oxide as a material suitable for the realization of low cost and large scale p-DSSCs [4]. the nanoparticles have been intensively studied as photocathodes materials for DSSCs because of their larger specific surface areas to absorb more dye molecules. At the same time, the small-sized particles have shown that the inefficient ability to scatter the solar radiation which reduces the light-harvesting efficiency. Based on these premises, we propose to investigate the effect of micrometer-size structures on the photovoltaic performance of p-DSSCs based on cuprous oxide. In this work, 3D hierarchical structure built of the micrometer dendritic rods and the porous truncated octahedrons have been successfully synthesized via a facile one-step hydrothermal methods using copper (II) acetate and ethyl cellulose as reactants. The DSSC based on the porous structure exhibits approximately 15% increase in JSC and VOC than 3D hierarchical structure. XRD patterns of the Cu2O_1 and Cu2O_2 compound, obtained from hydrothermal method are shown in figure 1. All the diffraction peaks could be indexed as Cu2O (cuprite) with cubic structure (space group: Pn-3m; JCPDS Nr. 01-074-1230), only a small amount of CuO is detected as impurity in Cu2O_2 sample. The formation of CuO phase is determined by the time reaction which in the case of Cu2O_2 is still small to establish completely Cu+1 oxidation state
