Structure Engineering of Self- and Directed-Assembled conjugated polymers

Abstract

Due to their unique electrical, optical and mechanical properties, conjugated polymers are promising candidates for a variety of devices, including transistors, optoelectronics, sensors, batteries, memories, spintronics and bioelectronics. However, further development of those applications calls for effective charge transport of conjugated polymers. Engineering their assembly to form ordered structures is key to enhancing the electrical properties. In this dissertation, external electric and acoustic fields have been demonstrated to effectively direct polymer assembly into fibers and the addition of polar poor solvents can self-assemble donor-acceptor conjugated polymers into nanoribbons with long-range order. To form detailed correlations between external controllable variables and the resulted nanostructures, a systematic investigation on the effects of tuning electric field frequency and amplitude, acoustic field peak negative pressure, as well as poor solvent polarity, is performed. Structure-property relationships are formed and mechanistic discussions on directed- and self- assembly are presented. Different polymers are explored to form general molecular design guidelines that can be beneficial to structure manipulation. This work provides insights into engineering structures for enhanced charge transport by controlling the assembly of conjugated polymers.