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

Journal article

Organic 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. © 2006 IEEE.

Authors: Schwenn, P; Watt, A; Rubinsztein-Dunlop, H; Meredith, P

• Journal: Proceedings of the 2006 International Conference on Nanoscience and Nanotechnology, ICONN
• Pages: 411-414
• Publication date: 2006-01-01
• DOI: 10.1109/ICONN.2006.340640
• Language: English
• Keywords: P3HT; Conducting polymer; MEH-PPV; Quantum dot; Nanocrystals; Lead sulfide; Photovoltaic