Nanoscience and Microsystems ETDs

Publication Date

Winter 11-15-2021

Abstract

Through-bond and through-space interactions between chromophores are shown to have wide-ranging effects on photophysical outcomes upon light absorption in organic molecules. In collapsed poly(3-hexylthiophene), through-space coupling creates hybrid chromophores that act as energy sinks for nearby excitons and favorable sites for molecular oxygen to dock. Upon excitation with visible light the highly-coupled chromophores react with the docked oxygen and subsequently do not quench nearby excitons as efficiently. In tetramer arrays of perylene diimide chromophores the central moiety through-bond connectivity is synthesized in two variants which exhibit vastly different single-molecule blinking behavior and theoretically-predicted electronic transition character. In the more-connected tetramer oxygen has a more holistic and destructive effect, and we see the opposite results in the less-connected tetramer; triplet excitons are implicated as an intermediary state. Finally, using kinetic models from published transient absorption experiments on multiple intramolecular singlet-fission dimers with similar chromophores but important through-bond connectivity differences, we predict the results of steady-state and microsecond timescale fluorescence experiments using stochastic methods.

Keywords

photophysics, spectroscopy, organic molecules, kinetic monte carlo, microscopy

Document Type

Thesis

Language

English

Degree Name

Nanoscience and Microsystems

Level of Degree

Doctoral

Department Name

Nanoscience and Microsystems

First Committee Member (Chair)

John K. Grey

Second Committee Member

David Keller

Third Committee Member

Terefe Habteyes

Fourth Committee Member

Alejandro Manjavacas

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