Regioisomeric Polythiophene Derivatives: Synthesis and Structure-Property Relationships for Organic Electronic Devices

• Published in: Macromolecular research 2020, 28(8), , pp.772-781
• Main Authors: Lee, Young Woong, Pak, Kawon, Park, Song Yi, An, Na Gyeong, Lee, Junghoon, Kim, Jin Young, Woo, Han Young
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Charge transport; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Copolymers; Electrical properties; Electronic devices; Fullerenes; Hole mobility; Molecular conformation; Nanochemistry; Nanotechnology; Organic semiconductors; Photovoltaic cells; Physical Chemistry; Polymer Sciences; Polymers; Polythiophene; Soft and Granular Matter; Solar cells; Steric hindrance; Topology; Transistors; Transport properties; 고분자공학
• ISSN: 1598-5032; 2092-7673
• DOI: 10.1007/s13233-020-8097-x

Three types of tail-to-tail (PDCBT TT ), head-to-tail (PDCBT HT ), and head-to-head (PDCBT HH ) regioisomeric polythiophene copolymers were synthesized by modification of the substitution positions of their alkoxycarbonyl side-chains. Chain conformation, and optical, electrochemical, morphological, and charge-transport characteristics of the polymers were significantly influenced by their regiochemistry. PDCBT HH showed an amorphous morphology due to strong steric hindrance between its head-to-head alkoxycarbonyl side-chains, resulting in the poorest performance in organic solar cells and transistors among three types. PDCBT HT had a regiorandom structure with both head-to-tail and tail-to-head linkages in a polymer chain. As determined by field-effect mobility measurements, a highly regioregular and planar PDCBT TT exhibited the highest hole mobility (μ = 0.065 cm 2 V -1 s -1 ), which was two orders of magnitude higher than that of the regiorandom PDCBT HT . The highest photovoltaic performance was also measured for PDCBT TT :a fullerene acceptor (PC 71 BM), by maintaining the packed structures of pristine PDCBT TT polymers in the blend with PC 71 BM. Altering the topology of alkoxycarbonyl side-chains of the copolymers resulted in significant differences in crystalline morphologies and electrical properties and thus should be carefully considered in the molecular design of organic semiconductors.