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Degree

MS, University of Cincinnati, Engineering and Applied Science: Materials Science, 2012.

Abstract

Organic photovoltaic systems (OPVs) have generated considerable interest as materials relevant to harnessing renewable and sustainable sources of energy and providing cost effective conversion of solar radiation to electrical power. When a conjugated polymer and fullerene molecules are amalgamated intimately, they form interpenetrating mixture of microphases referred to as bulk heterojunction (BHJ). The BHJ enables the dissociation of photogenerated electron-hole pairs i.e. excitons. The increased surface area and the percolating network of conjugated polymers and nanofillers leads to higher power conversion efficiencies. Although it is believed that the C60 nanofillers affect the morphology of the conjugated polymers and influences final device efficiency, a complete understanding of the underlying mechanisms is lacking. Molecular dynamics simulations have been used to study the interface between quaterthiophene and fullerene, prototypical molecules mimicking bulk heterojunction in organic solar cells. The simulation provides fundamental insights investigating the ordering behavior of the polymer morphology that provides optimized generation of free charges from photogenerated excitons in such assemblies, as studied by experiment. Well tested and accurate force-fields that represent both the polymer and the fullerene phase have been employed. In particular, we focus on the morphology of the polymer chains adjacent to the substrates by evaluating order parameters that probe chain orientation and interchain packing. The dynamics of chain back bone and rings constituting the chain; orientational effects of the substrate on the polymer are investigated. The ultimate goal of the research was to employ molecular simulations which elucidate the principle rules that influence overall efficiency in organic photovoltaic systems.

Subject Headings

Materials Science

Keywords

photovoltaics; efficiency; morphology; molecular dynamics; orientation; stacking

Committee / Advisors

Vikram Kuppa, PhD (Committee Chair)
Gregory Beaucage, PhD (Committee Member)
Vadim Guliants, PhD (Committee Member)

Pages

90p.

Document number: ucin1342545038
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342545038

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