Intramolecular Locked Dithioalkylbithiophene-Based Semiconductors for High-Performance Organic Field-Effect Transistors.

Vegiraju, Sureshraju; Chang, Bo-Chin; Priyanka, Pragya; Huang, Deng-Yi; Wu, Kuan-Yi; Li, Long-Huan; Chang, Wei-Chieh; Lai, Yi-Yo et al. · Adv Mater · 2017

basic_science · Level V

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Abstract

New 3,3'-dithioalkyl-2,2'-bithiophene (SBT)-based small molecular and polymeric semiconductors are synthesized by end-capping or copolymerization with dithienothiophen-2-yl units. Single-crystal, molecular orbital computations, and optical/electrochemical data indicate that the SBT core is completely planar, likely via S(alkyl)⋯S(thiophene) intramolecular locks. Therefore, compared to semiconductors based on the conventional 3,3'-dialkyl-2,2'-bithiophene, the resulting SBT systems are planar (torsional angle <1°) and highly π-conjugated. Charge transport is investigated for solution-sheared films in field-effect transistors demonstrating that SBT can enable good semiconducting materials with hole mobilities ranging from ≈0.03 to 1.7 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup> . Transport difference within this family is rationalized by film morphology, as accessed by grazing incidence X-ray diffraction experiments.