Geometric, electronic and optical properties of organic charge transfer systems: Photovoltaic blends and donor-acceptor co-crystals

dc.contributor.advisor Brédas, Jean-Luc
dc.contributor.author Ashokan, Ajith
dc.contributor.committeeMember Sherrill, David
dc.contributor.committeeMember Reynolds, John
dc.contributor.committeeMember Reichmanis, Elsa
dc.contributor.committeeMember Silva, Carlos
dc.contributor.department Chemistry and Biochemistry
dc.date.accessioned 2020-05-20T16:59:13Z
dc.date.available 2020-05-20T16:59:13Z
dc.date.created 2020-05
dc.date.issued 2020-04-03
dc.date.submitted May 2020
dc.date.updated 2020-05-20T16:59:13Z
dc.description.abstract Over the past two decades, π-conjugated organic molecules have found applications in the active layer of different types of organic electronic devices. To optimize and improve the performance of each of these devices, it is important to establish clear connections between chemical-structure, intermolecular packing and their impact on the electronic and charge transport properties in these systems. In this Thesis, we focus on two-component organic material systems – one acting as a π-electron donor (D) and the other as a π-electron acceptor (A) for applications in organic photovoltaics (OPV) and organic field-effect transistors (OFETs). On the OPV side (Chapters 3 & 4), initially, we investigate the solution temperature-dependent aggregation property of a few polymers in their pure phases, which has been recently established as a potential method for morphology control in high-performing OSC devices. We then explore the intermolecular packing properties in the binary blends of polymer and two small molecule acceptors, which in their binary as well as ternary combinations exhibit high power conversion efficiencies. We elucidate clear connections between the molecular scale features that impact the device parameters in both the binary blends. We also obtain useful trends to explain the linear evolution of device parameters in the ternary blends. On the OFET side (Chapters 5 & 6), our focus is on DA charge-transfer co-crystals, which possess potential applications as active layer components in OFET devices. Initially, we investigate the effect of packing on electronic properties of co-crystals based on F6TNAP acceptor and a series of donor molecules. Further, we focus on understanding the evolution in electronic, vibrational and charge-transport properties with sequential addition of alkyl chains on the donor and fluorine atoms on the acceptor on co-crystals based on BTBT-FmTCNQ (m=0, 2, 4) and di-CnBTBT-FmTCNQ (n=8, 12; m=0, 4) series. Finally, we explore the degree of charge-transfer in these systems using an approach based on Mulliken charges. While these results are limited to the systems under consideration, our simulations provide a reliable, molecular-level understanding to systematically improve the morphological characteristics that impact the device performances in organic electronic devices.
dc.description.degree Ph.D.
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/62748
dc.publisher Georgia Institute of Technology
dc.subject Morphology
dc.subject Molecular dynamics simulations
dc.subject Polymer
dc.subject Non-fullerene acceptor
dc.subject DFT calculations
dc.subject Bandstructure
dc.subject Co-crystals
dc.title Geometric, electronic and optical properties of organic charge transfer systems: Photovoltaic blends and donor-acceptor co-crystals
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Brédas, Jean-Luc
local.contributor.corporatename School of Chemistry and Biochemistry
local.contributor.corporatename College of Sciences
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relation.isOrgUnitOfPublication f1725b93-3ab8-4c47-a4c3-3596c03d6f1e
relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
thesis.degree.level Doctoral
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