Drastic Effects of Fluorination on Backbone Conformation of Head-to-Head Bithiophene-Based Polymer Semiconductors

Qiaogan Liao; Yulun Wang; Mohammad Afsar Uddin; Jianhua Chen; Han Guo; Shengbin Shi; Yang Wang; Han Young Woo; Xugang Guo

doi:10.1021/acsmacrolett.8b00032

Drastic Effects of Fluorination on Backbone Conformation of Head-to-Head Bithiophene-Based Polymer Semiconductors

ACS Macro Lett. 2018 May 15;7(5):519-524. doi: 10.1021/acsmacrolett.8b00032. Epub 2018 Apr 11.

Authors

Qiaogan Liao¹, Yulun Wang¹, Mohammad Afsar Uddin², Jianhua Chen¹, Han Guo¹, Shengbin Shi¹, Yang Wang¹, Han Young Woo², Xugang Guo¹

Affiliations

¹ Department of Materials Science and Engineering and The Shenzhen Key Laboratory for Printed Organic Electronics, South University of Science and Technology of China (SUSTC), No. 1088, Xueyuan Road, Shenzhen, Guangdong 518055, China.
² Department of Chemistry, Korea University, Seoul 136-713, South Korea.

PMID: 35632924
DOI: 10.1021/acsmacrolett.8b00032

Abstract

This study shows that the backbone conformation of head-to-head type 3,3'-dialkyl-2,2'-bithiophene can be tuned via fluorination of the neighboring benzothiadiazole (BTz). Without fluorination, the polymer backbone is highly twisted, whereas difluorination of BTz produced a coplanar backbone. Monofluorination of BTz yielded a tunable polymer backbone conformation depending on the film annealing temperature. In organic thin-film transistors, the polymer with the head-to-head linkages showed a remarkable hole mobility of >0.5 cm² V^-1 s^-1 upon attaining a planar backbone. Thus, the head-to-head linkage does not necessarily lead to backbone nonplanarity, and achieving planar conformation of 3,3'-dialkyl-2,2'-bithiophene has profound implications in materials design for organic semiconducting devices, yielding good solubility, reduced materials synthetic steps, and improved opto-electrical properties.