© 2019, © 2019 Taylor & Francis Group, LLC. In this study, the effect of periodic patterned micro/nanostructures on the active layers of thin-film organic photovoltaics (OPVs) was investigated to improve the device performance. The patterned active layer structures were fabricated by a nanoimprinting technique using different templates, including compact disc recordable (CD-R), Blu-ray disc recordable (BD-R), nanowell arrays, nanodot arrays, and honeycomb structures. The OPVs consisted of Al/nanostructured P3HT:PCBM/PEDOT:PSS/ITO. Compared with a flat reference OPV, all the micro/nanostructured OPVs exhibited higher performances, originating from enhanced light absorption due to light scattering and surface plasmon excitation at the patterned Al/P3HT:PCBM interfaces.