Study on ZnO/P3HT:PCBM nanowire solar cells

A combination of bulk heterojunction and ZnO nanowires (NWs) for solar cell application has been investigated. The bulk heterojunction materials include poly (3-hexylthiophene):(6, 6)-phenyl C
₆₀
butyric acid methyl ester (P3HT: PCBM). The effects of nanowire length, coating processes, and surface modification of ZnO NWs by tetra (4-carboxyphenyle) [TCPP] on the optical properties and solar cell performance are studied. It is found that the short NWs and slow coating speed of P3HT: PCBM on ZnO NW arrays resulted in better performance of solar cells, which is attributed to a longer time self-organization of the polymer chain, effective infiltration into the gaps among ZnO NWs. In addition, the surface modification by porphyrin is found to increase the solar cell efficiency from 2.18 to 3.13% due to the improved optical absorption and charge transfer at the NW/P3HT:PCBM interfaces.