Optimization of double gyroid film synthesis for use in bulk heterojunction photovoltaics

Steven J Gaik, Purdue University

Abstract

Solar cells have not dominated the world energy market, because they require high startup capital costs and suffer from low energy conversion efficiencies. This research contributes to addressing the latter problem by expanding the synthesis of the unique double gyroid (DG) nanostructure for use in fabricating high efficiency photovoltaic devices. The processing conditions necessary for generating high quality DG films using evaporation induced self-assembly (EISA) are presented and discussed for a variety of substrates with different hydrophilic I'character and surface roughness. Similar processing windows, but differing reproducibility among substrates suggests self-assembly at the substrate-film interface may significantly affect film morphology. The ability to tune the DG film thickness between 100 nm and 700 nm, while maintaining a crack free DG topology, is important for matching the DG film thickness to the optical density of different semiconductors. This capability is demonstrated using two separate techniques. Ozone treatment, UV exposure, solvent extraction, and calcination treatments are compared as template removal procedures to expand the applicability of the DG structure to multiple electronically interesting substrates. The first report of a DG film synthesis with organosilica functionality is also presented, which demonstrates the generality of controlling nanostructure curvature using a controlled aging method. Finally, a list of characteristic indications of common synthesis problems is included with a summary of equipment enhancements that were performed to increase DG film production to 300 films per week.

Degree

M.S.

Advisors

Agrawal, Purdue University.

Subject Area

Chemical engineering

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