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-C₆₁-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 C₆₀/10 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 λ = 1205 nm.