Novel structures of photovoltaic cells (also called as solar cells) are provided. The cells are based on nanoparticles or nanometer-scaled wires, tubes, and/or rods, which are made of electrical materials covering semiconductors, insulators, and also metallic in structure. These photovoltaic cells have large power generation capability per unit physical area over the conventional cells. These cells will have enormous applications such as in space, commercial, residential and industrial applications.