We have developed an efficient, low temperature, synthetic route for ZnO nanoflowers(NFs) as photoanode material. This alternative route yields small flower-like nanostructures, built from densely self-assembled tip-ended rod structures. The obtained ZnO NFs possess a large bandgap of 3.27 - 3.39 eV, enabling the generation of an average open current voltage of 0.56 V. Additionally, they show a high internal light harvesting of 14.6·10-7A·mol-1. The growth mechanism and self-assembly of ZnONFs were studied in detail by joint spectroscopic-TEM investigations. It is shown thatthe ZnO crystallite size increases with increasing annealing temperatures and that thestress and the improved crystallinity are induced by annealing and reduce the latticestrain and the dislocation density. The bandgaps of ZnO are affected by the lattice strain revealing an optimal region of lattice strain to gain high bandgap energies. The properties of the synthesized ZnO NFs are compared with other morphologies, i.e. ZnO spherical aggregates (SPs) and ZnO nanorods (NRs), and are tested as electrode materials in dye-sensitized solar cells.