Graphene-Enriched P3HT and Porphyrin-Modified ZnO Nanowire Arrays for Hybrid Solar Cell Applications

A hybrid structure containing graphene-enriched poly(3-hexylthiophene) (G-P3HT) and tetra(4-carboxyphenyle) porphyrin-grafted ZnO nanowire arrays has been investigated for nanowire/polymer hybrid solar cell applications. The vertically aligned nanowires embedded in the organic films act as an active n-type semiconductor and a high-efficiency charge collection electrode. The surface grafting of ZnO nanowires by porphyrin was found to improve significantly the cell efficiency as compared with those using pristine ZnO nanowires. The improvement is attributed to the enhanced light harvesting and charge injection with the presence of porphyrin at the junction interface. A comparison study showed that the use of G-P3HT further increased the efficiency of the nanowire solar cells from 0.09 to 0.4%, benefiting from the improved hole collection with graphene in the polymer. This study indicates that hybrid structure comprising surface modified, vertically aligned ZnO nanowire arrays embedded in G-P3HT is promising for solar cell applications.