Single-Particle Spectroscopy On Conducting Polymer-Fullerene Composite Materials For Application In Organic Photovoltaic Devices

The study of the photophysical and optoelectronic properties of a functioning conducting polymer device is extremely complicated and is hampered by the complex nanostructure and overall morphology of the conducting polymer materials applied in these devices. Here we discuss a novel approach to investigate this issue spectroscopically in terms of bulk-heterojunction organic photovoltaic devices. Novel composite nanoparticles of the conjugated polymers MEH-PPV and P3HT blended with the fullerene PCBM were fabricated and are observed to be excellent simplified model systems for the study of molecular-scale morphology effects at play in these complex nanostructured materials. Single particle spectroscopy reveals the extent to which variations in polymer-chain folding and interactions between polymer chains and fullerenes affect material morphology, spectral properties, and optoelectronic properties, providing a detailed molecular scale insight into the morphological effects at play in the active layers of bulk-heterojunction organic photovoltaic devices that otherwise would be masked by the presence of the bulk