Abstract
The interaction between fullerene molecules and poly [2-methoxy-5-(2′-ethyl)hexoxy-1,4-phenylenevinylene] (MEH-PPV) has been studied to investigate the role of charge pair separation and photocurrent generation in organic photovoltaic films. UV–visible spectrophotometry, photoluminescence and electrical characterization of the composites have been studied as a function of the fullerene concentration. Photoluminescence (PL) spectroscopy shows the existence of a critical fullerene concentration of about 7vol.% for PL quenching where efficient charge separation is reached. The conductivity of the composite films increases by four orders of magnitude as the fullerene concentration increases to 40vol.%. The conductivity enhancement is interpreted by the formation of a conducting path for an estimated percolation threshold of 40vol.%.