Synthesis and Characterization of Thieno[3,2-b]Pyrrole Based Organic Semiconductors for Organic Field Effect Transistors



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Organic semiconductors (OSCs) are used as electro-active materials across numerous different applications, such as organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), and organic field effect transistors (OFETs). This versatility owes to their low cost, light weight, flexibility, solution processability, and ease of large area fabrication. Tremendous efforts have been devoted to designing OSCs with various building blocks in order to obtain more desirable optoelectronic properties. However, there is still a high demand for further improvements in OSC properties. The development of pyrrole-based OSCs for organic electronic applications, fused ring systems containing S,N-heteroacenes, and the working principles of OFETs are discussed in Chapter 1, along with a summary of performance of S,N-heteroacene materials in organic electronic applications. Chapter 2 discusses the tunable optoelectronic properties of thieno[3,2-b]pyrrolebased organic semiconductors synthesized by varying the -linker. Chapter 3 discusses the effects of using selenophene as a -spacer in thieno[3,2-b]pyrrole and benzo[c][1,2,5]thiadiazole based donor-acceptor molecule on OFETs parameters. The change of the -spacer to selenophene in the molecule affects its bond curvature and, consequently the molecule adopted less bond curvature compared to its furan and thiophene analogs. The molecule showed p-type charge carrier mobility characteristics in devices with bottom-gate/bottom-contact configuration. Chapter 4 describes how the change of -spacer to acquire different backbone curvatures in small molecules synthesized with thieno[3,2-b]pyrrole and benzo[c][1,2,5]thiadiazole impacted p-type OFETs characteristics. Two spacers, bithiophene and thieno[3,2-b]thiophene, produced two different backbone curvature and resulted in a drastic difference in their OFET performance.



Pyrroles, Organic field-effect transistors, Organic semiconductors