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Polymer Sciences | ISSN: 2471-9935
October 02-03, 2017 Chicago, USA
3
rd
International Conference on
Polymer Science and Engineering
Self-assembly and sequential processing for morphology control over organic photovoltaics and chemical
doping of conjugated polymers
Benjamin J Schwartz
University of California- Los Angeles, USA
O
ne of the key issueswith improving the efficiency of conjugatedpolymer-basedphovoltaics is controlling the nm-scalemorphology
of the two active components. Typically, efficiency is optimized by trial-and-error: component weight ratios, solvent additives,
post- processing thermal annealing, etc. are all used to attempt to obtain the desired bulk heterojunction (BHJ) interpenetrating
network. In this talk, I discuss some of my group's recent work aimed at using alternate, more reproducible methods for controlling
BHJ morphology. Our results include the use of new amphiphilic semiconducting polymers and fullerenes that spontaneously
selfassembly into co-axial cylindrical micelles in solution, and thus provide a built-in connected network when cast into gels that
form thin films. Photoexcitation of the polymer in these systems produces separated charges on sub-ps time scales, and the separated
charges are stable for weeks to months in air-free environments. We also show that sequential processing of the polymer and fullerene
components can provide an exquisite degree of control of the nm-scale morphology of a BHJ, and that the degree of crystallinity
of the polymer controls both the amount of intercalated fullerene and the geometry of the interpenetrating network. Finally, we
demonstrate that sequential processing also can be used to infiltrate molecular dopants into films of conjugated polymers, providing
improved film quality and allowing access to the physics of the mobile carriers in doped polymers that were previously unavailabl
schwartz@chem.ucla.eduPolym Sci, 3:3
DOI: 10.4172/2471-9935-C1-003