Hole Transport in Poly(phenylene vinylene)/Methanofullerene Bulk-Heterojunction Solar Cells

✍ Scribed by C. Melzer; E. J. Koop; V. D. Mihailetchi; P. W. M. Blom

• Publisher: John Wiley and Sons
• Year: 2004
• Tongue: English
• Weight: 246 KB
• Volume: 14
• Category: Article
• ISSN: 1616-301X
• DOI: 10.1002/adfm.200305156

✦ Synopsis

Abstract

A fundamental limitation of the photocurrent of solar cells based on a blend of poly(2‐methoxy‐5‐(3′,7′‐dimethyloctyloxy)‐p‐phenylene vinylene) (MDMO‐PPV) and [6,6]‐phenyl C~61~‐butyric acid methyl ester (PCBM) is caused by the mobility of the slowest charge‐carrier species, the holes in the MDMO‐PPV. In order to allow the experimentally observed photocurrents electrostatically, a hole mobility of at least 10^–8^ m^2^ V^–1^ s^–1^ is required, which exceeds the observed hole mobility in pristine MDMO‐PPV by more than two orders of magnitude. However, from space‐charge‐limited conduction, admittance spectroscopy, and transient electroluminescence measurements, we found a hole mobility of 2 × 10^–8^ m^2^ V^–1^ s^–1^ for the MDMO‐PPV phase in the blend at room temperature. Consequently, the charge‐carrier transport in a MDMO‐PPV:PCBM‐based solar cell is much more balanced than previously assumed, which is a necessary requirement for the reported high fill factors of above 50 %.