Semiconducting carbon nanotube/fullerene blended heterojunctions for photovoltaic near-infrared photon harvesting

We demonstrate that the near-infrared (NIR) absorptivity of semiconducting single-walled carbon nanotubes (s-SWCNTs) can be harnessed in blended heterojunctions with the fullerene derivative [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM). Photogenerated charge separation is efficiently driven by the ultrahigh interfacial area of the blends and the favorable energy offsets between the two materials. NIR-sensitive photovoltaic and photodetector devices utilizing the stack (indium tin oxide/ca. 10 nm s-SWCNT:PCBM/100 nm C-60/10 nm 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP)/Ag) were fabricated with NIR power conversion efficiencies > 1.3% and peak, zero bias external quantum efficiency of 18% at lambda = 1205 nm.