Recombination-Limited Photocurrents in Low Bandgap Polymer/Fullerene Solar Cells

✍ Scribed by Martijn Lenes; Mauro Morana; Christoph J. Brabec; Paul W. M. Blom

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 195 KB
• Volume: 19
• Category: Article
• ISSN: 1616-301X
• DOI: 10.1002/adfm.200801514

✦ Synopsis

Abstract

The charge transport and photogeneration in solar cells based on the low bandgap‐conjugated polymer, poly[2,6‐(4,4‐bis‐(2‐ethylhexyl)‐4__H__‐cyclopenta[2,1‐b; 3,4‐b′]dithiophene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)] (PCPDTBT) and fullerenes is studied. The efficiency of the solar cells is limited by a relatively low fill factor, which contradicts the observed good and balanced charge transport in these blends. Intensity dependent measurements display a recombination limited photocurrent, characterized by a square root dependence on effective applied voltage, a linear dependence on light intensity and a constant saturation voltage. Numerical simulations show that the origin of the recombination limited photocurrent stems from the short lifetime of the bound electron‐hole pairs at the donor/acceptor interface.