A “building block” concept is introduced for the construction of electrodes for dye-sensitized solar cells (DSCs). The building blocks are prefabricated submicrometer- to micrometer-sized clusters, such as nanostructured mesoporous TiO2 spheres. This concept makes a number of approaches possible that are difficult to achieve through the conventional nanoparticle route for the preparation of flexible DSCs. Significantly, the building blocks can be physically and chemically pre-treated prior to electrode fabrication. Thus some of the intrinsic limitations of using plastic substrates can be overcome, such as applying heat treatment and TiCl4 treatment, affording a high power conversion efficiency of 7.5%.