Concentration dependence of photovoltaic properties of photodiodes based on polymer-fullerene blends

Photovoltaic properties of photodiodes based on the blends of poly [2-methoxy-5-(2'-ethylhexoxy-1,4-phenylenevinylene) (NMH-PPV) and fullerene (C-60) are investigated. The experimental results show that the open-circuit voltage (V-oc) declines with the increasing concentration of C-60. A big variation of similar to 400 mV in the V-oc for the devices with the concentration of 0% and 50% indicates the electron affinity potential of C-60 can strongly influence the resulting V-oc. At the bias of -1.5 V, the photosensitivity of the device with the concentration of 50% is 55.6 mA/W under the illumination intensity of 16.7 mW/cm(2) and its photogain sharply rises by two orders of magnitude than that of the undoped MEH-PPV device. (c) 2006 Elsevier B.V. All rights reserved