Effect of conducting polymer molecular weight on nanocrystal growth size for photovoltaic applications

TitleEffect of conducting polymer molecular weight on nanocrystal growth size for photovoltaic applications
Publication TypeJournal Article
Year of Publication2006
AuthorsSchwenn, P. E., Watt A. A. R., Dunlop H. R., and Meredith Paul
Journal2006 International Conference On Nanoscience And Nanotechnology, Vols 1 And 2
Volume-
Pagination268–271
AbstractOrganic photovoltaics promise a number of key advantages over conventional silicon, namely: Ease of processing, low cost, physical flexibility and large area coverage. However, the solar power conversion efficiencies of pure polymer devices are poor. When electron acceptor nanocrystals are blended with a donor conducting polymer to create a bulk heterojunction structure, the optical and electronic properties of both materials combine synergistically to enhance overall performance. We use a novel single pot process to fabricate the nanocomposite photovoltaic material, where PbS nanocrystals are grown directly in a solution of the conducting polymer MEH-PPV. This study investigates the dependence of nanocrystal growth size and subsequent power conversion efficiency as a function of polymer molecular weight. It was found that a higher molecular weight polymer resulted in the formation of a broken percolation of smaller nanocrystals that act to enhance the charge separation of excitons generated at the low energy band edge of MEH-PPV.