P3HT:PCBM Bulk Heterojunction Solar Cells Characterization by Spectroscopic EllipsometryOptical Discs

The performance of organic solar cells based on the blends of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) is strongly influenced by blend composition and thermal annealing conditions. For high-efficiency solar cells, a nanoscale interpenetrating network with crystalline order of both constituents is the desirable architecture for the photoactive layer. To that end, recent studies have focused on how to tailor and control the morphology of the P3HT:PCBM blend, the material combination that has led to the highest power conversion efficiency values reported thus far (4-5%). In this note, we demonstrate the use of ellipsometry as a powerful and sensitive metrology means of monitoring blend morphology, phase separation as well as crystallinity. Spectroscopic Ellipsometry is an optical technique for the characterization of thin films, mainly used to determine film thickness and optical constants of single or multilayer stacks. SE25