Unique light-matter interaction at nanophotonic regime can be harnessed for designing efficient photonic and optoelectronic devices such as solar cells, lasers, and photodetectors. In this work, periodic photon nanowells are fabricated with a low-cost and scalable approach, followed by systematic investigations of their photon capturing properties combining experiments and simulations. Intriguingly, it is found that a proper periodicity greatly facilitates photon capturing process in the nanowells, primarily owing to optical diffraction. Meanwhile, the nanoengineered morphology renders the nanostructures with a broad-band efficient light absorption. The findings in this work can be utilized to implement a new type of nanostructure-based solar cells. Also, the methodology applied in this work can be generalized to rational design of other types of efficient photon-harvesting devices.