Subnanosecond geminate charge recombination in polymer-polymer photovoltaic devices

Phys Rev Lett. 2010 Apr 30;104(17):177701. doi: 10.1103/PhysRevLett.104.177701. Epub 2010 Apr 29.

Abstract

We present direct spectroscopic evidence for substantial subnanosecond charge recombination in polymer-polymer blend photovoltaic devices. Early dynamics are dominated by exciton-charge interactions associated with high initial excitation densities. Independent of density, 30% of charges subsequently recombine geminately within just 2 nanoseconds, in contrast with fullerene blends. The remainder recombines with a half-life of approximately 200 ns. The morphological invariance of subnanosecond recombination suggests that its origin is inherent in the molecular structure at the polymer-polymer interface.