Plastic Optoelectronics: Injection Lasers Fabricated from Soluble Semiconducting Polymers and Bulk Heterojunction Solar Cells Fabricated from Soluble Semiconducting Polymers; Final rept. 15 Feb 2005-31 Dec 2007

摘要

We summarize progress on bulk heterojunction (BHJ) 'plastic' solar cells: BHJ solar cells are based on phase-separated blends of polymer semiconductors and fullerene derivatives. Because of self-assembly on the nanometer length scale, excitons formed after absorption of solar irradiation diffuse to a heterojunction prior to recombination and are dissociated at the polymer/fullerene interface. Ultrafast charge transfer from semicondueting polymers to fullerenes guarantees that the quantum efficiency for charge transfer (CT) at the interface approaches unity, with electrons on the fullerene network and holes on the polymer network. Electrons migrate toward the lower work function metal and holes migrate toward the higher work function metal. Carrier recombination prior to reaching the electrodes and low mobility limit both the device fill factor (FF) and the overall photon harvesting by reducing the optimum active layer thickness. The carrier lifetime is largely controlled by the phase morphology between the donor and acceptor materials. We also summarize the results obtained to demonstrate the realization ofthe Light emitting Field effect Transistors.