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This thesis is focused on applying direct heteroarylation as an efficient synthetic route to access new π-conjugated molecular materials for use in organic solar cells. Chapter one introduces π-conjugated materials, organic solar cells, and design considerations in the development of sustainable and efficient methods towards accessing high-performance materials. Chapter two introduces a novel π-conjugated building block, indoloquinoxaline, which is available from inexpensive starting materials and can be accessed from a modular and high yielding synthesis. Its materials’ properties are investigated through its incorporation as a terminal unit in three different molecular constructs (1-3) using Stille couplings and the more economical direct heteroarylation coupling. Building directly from this work, chapter three focuses on the use of the indoloquinoxaline building block and its fluorinated derivative to access a series of π-extended squaraine dyes (4-7) via Sonogashira and direct heteroarylation couplings expanding the substrate scope of the latter more versatile and atom-economical cross-coupling. Chapter four applies the synthetic methods developed in chapters two and three and extends these principles to the design and synthesis of an asymmetric π-conjugated molecular structure combining the organic dyes, perylene diimide, diketopyrrolopyrrole, and indoloquinoxaline in a linear fashion via direct heteroarylation (8). The asymmetric compound 8 is exploited for its low energy absorption as a non-fullerene acceptor in organic solar devices. Adapting the synthetic protocols from chapter four, chapter five explores the incorporation and effect of a rylene building block new to organic electronics, N-(alkyl)benzothioxanthene- 3,4-dicarboximide (BTXI), on materials properties in order to learn more about its potential use in organic electronic applications (9-11). The three molecular semiconductors (9-11) are compared and evaluated in organic thin-film transistors and organic solar cells. Chapter six concludes this thesis detailing unprecedented direct heteroarylation reactivity which is uncovered and exploited in order to access a novel tetrameric perylene diimide (12) non-fullerene acceptor for organic solar cell applications. |
