Spectroscopic and Electrical Imaging of Polymer/Fullerene Solar Cell Materials: Understanding Morphology-Dependent Aggregation from the Molecular to Bulk Levels

摘要

New combinations of spectroscopic and electrical device imaging techniques are introduced to spatially map local structure-function relationships in disordered polymeric solar cell materials. Because the fashion in which polymer molecules pack and organize in thin film structures has a large influence on energy and charge transfer characteristics, there is presently intense interest in understanding the influence of local (nano- to microscale) morphology on the rates and yields of these key processes. Unfortunately, direct correlations between local chemical structure and packing characteristics are difficult to obtain using scanned probe microscopies as well as conventional spectroscopy. We use sensitive spectroscopic imaging tools along with electrical characterization techniques to interrogate polymeric composites in various functional forms in functioning device environments. These new approaches reveal the contributions of the local aggregation state (packing and conformation) of the polymer to device performance over the critical nano- to microscale size range.