A hierarchically-structured ZnO film consisting of secondary colloidal spheres of similar to 300 nm in diameter and primary nanoparticles of similar to 20 nm in diameter is shown to have an similar to 83% improvement in the overall light conversion efficiency, when compared to commercially-obtained ZnO film with similar to 25 nm particles. This increase is attributed to the hierarchical structure, where the secondary colloidal spheres promote light scattering for enhanced photon absorption.