Publication Type
Journal
Journal Name
Applied Physics Letters
Publication Date
Volume
103
Issue
22
Abstract
Understanding the origin for the film stratification of electron donor/acceptor blend is crucial for
high efficiency organic photovoltaic cell. In this study, P3HT:PCBM blend is deposited onto
hydrophilic and hydrophobic substrate to examine the film stratifications. The neutron reflectivity
results show that, on the different surfaces, PCBM diffuses toward the two interfacial regions in an
identical fashion during thermal annealing. This evidences that the film stratification is not affected
by the substrates. Instead, since P3HT remains more amorphous in the interfacial regions and
PCBM is miscible with amorphous P3HT, PCBM preferentially diffuses to the interfacial regions,
resulting in the stratification.