Abstract
We have explored the upconversion (UC) effects resulting from the presence of NaYF 4 :Yb/Er nanocrystals in near-infrared laser-driven organic photovoltaic devices (OPVs). Illumination of these UC nanomaterials with monochromatic light (980 nm) led to emission of visible light, which was subsequently absorbed by the polymer photoactive layer. We infer that both the long-wavelength charge-transfer absorption of the polymer blend and the UC effect contributed to the obvious near-infrared photovoltaic response. The resulting UC effects led to noticeable enhancements in the photocurrent and the efficiencies of the OPV devices under illumination at 980 nm. © 2012 Elsevier B.V. All rights reserved.