Structural/morphological monitoring approach to stability and durability issues of photoactive films for organic solar cells

Here we report on the effect of light on surface and bulk morphology, structural and optical properties of polymer/fullerene blends used for organic solar cells. The crystallization kinetics of the organic film molecules was followed in real time during illumination, by time-resolved X-ray diffraction, applied in-situ, jointly with atomic force microscopy. The occurrence of possible phase separation of the two components was detected. This latter hypothesis was confirmed by Fourier Transform Infrared spectroscopy experiments. As a result of such cross monitoring, a comprehensive picture of the chemical/physical process concurring to the devices photo-active layers aging was gained.