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dc.contributor.authorBotelho, André Leitãoen_US
dc.date.accessioned2018-10-25T12:44:46Z
dc.date.issued2012
dc.date.submitted2012
dc.identifier.otherb39007558
dc.identifier.urihttps://hdl.handle.net/2144/31512
dc.descriptionThesis (Ph.D.)--Boston Universityen_US
dc.descriptionPLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.en_US
dc.description.abstractThe adapted Su-Schrieffer-Heeger model is developed in this work as a tool for in silico prediction of the optical gap of conjugated systems for photovoltaic applications. Full transferability of the model ensures reliable predictive power - excellent agreement with 180 independent experimental data points covering virtually all existing conjugated system types with an accuracy exceeding the time-dependent density functional theory, one of the most accurate first-principles methods. Insights on the structure-property relation of conjugated systems obtained from the model lead to guiding rules for optical gap design: 1) fusing aromatic rings parallel to the conjugated path does not significantly lower the optical gap, 2) fusing rings perpendicularly lowers the optical gap of the monomer, but has a reduced benefit from polymerization, and 3) copolymers take advantage of the lower optical gap of perpendicular fused rings and benefit from further optical gap reduction through added parallel fused rings as electronic communicators. A copolymer of parallel and perpendicular benzodithiophenes, differing only in sulfur atom locations, is proposed as a candidate to achieve the optimal 1.2 eV donor optical gap for organic photovoltaics. For small-molecule organic photovoltaics, substituting the end pairs of carbon atoms on pentacene with sulfur atoms is predicted to lower the optical gap from 1.8 eV to 1.1 eV. Furthermore, the model offers an improvement of orders of magnitude in the computational efficiency over commonly used first-principles tools.en_US
dc.language.isoen_US
dc.publisherBoston Universityen_US
dc.titlePredicting the optical gap of conjugated systemsen_US
dc.typeThesis/Dissertationen_US
dc.description.embargo2031-01-01
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineEngineeringen_US
etd.degree.grantorBoston Universityen_US
dc.identifier.barcode11719032087977
dc.identifier.mmsid99176431190001161


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