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Owing to its unique 2-dimensional carbon nanostructure with unique electrical, optical, thermal, and mechanical properties, graphene has attracted a great deal of interest. While the pristine graphene is a zero-bandgap material with metal-like conductivity, graphene nanoribbon (GNR) is semiconducting with an opened bandgap induced by the quasi-one-dimensional confinement of charge carriers. However, graphene and its nanoribbons without functionalization are insoluble and infusible. The poor processability has precluded the pristine graphene materials, including GNR, for various potential applications. This limitation has been circumvented by oxidizing graphene with acids (e.g., H 2 SO 4 /KMnO 4) to produce graphene oxide (GO) with oxygen-containing groups (e.g., COOH, OH) around and on the carbon basal plane, leading to low-cost mass production of soluble graphene derivatives for potential applications. By introducing the oxygen-rich groups around a graphene nanoribbon, the resultant graphene oxide nanoribbon (GOR) should show a synergistic effect to have the bandgap of GNR and solution processability of GO. Therefore, GORs could be a new class of solution- processable semiconducting materials attractive for optoelectronic applications. In this study, we demonstrate, for the first time, that GOR can be used as an excellent hole-extraction material to significantly improve the performance of polymer solar cells (PSCs). PSCs using polymeric materials to convert solar energy to electricity is an emerging photovoltaic technology to compete with the widely used photovoltaic technologies based on inorganic materials. In spite of many advantages (e.g., low cost, flexibility, and semi-transparency), the efficiency and lifetime of PSCs are still largely limited by, among other factors, the poor charge extraction from the active layer to electrodes.