Abstract
Organic Solar Cells fabricated by conjugated polymer using solution-based processes are light-weighted, cost-effective in manufacturing and scalable to large-area devices. Due to the low electron mobility of conjugated polymer, it is believed that using materials which can efficiently transport electron may enhance the performance of the solar cells. We fabricate the active layer of solar cells by using blends of P3HT and colloidal CdSe nanorods. Colloidal nanorods are soluble in organic solvent and are able to provide a direct route for electron transport due to their anisotropic shape. Active layer spin coated by blend forms bulk heterojunction, which provide a large area of interface between P3HT and CdSe for charge separation. Efficient charge separation occurs at the interface of polymer and inorganic nanocrystals due to the heterojuntion structure, the short-circuit current of blend is 100 times larger than P3HT single layer. We successfully fabricate basic solar cell devices, and study the effects of processing steps. We find that surfactant exchange of CdSe nanorods is critical for charge separation and using mixed solvent will prevent nanorods from aggregation. The use of heat treatment and high-boiling-point solvent for blend enhances the performance of solar cells, which is tentatively attributed to more orderly arrangement of the polymer under these processing steps.