Regioregular-<i>block</i>-Regiorandom Poly(3-hexylthiophene) Copolymers for Mechanically Robust and High-Performance Thin-Film Transistors

다국어 초록 (Multilingual Abstract)

<P>In this work, we develop mechanically robust and high-performance organic thin-film transistors (OTFTs) based on poly(3-hexylthiophene) (P3HT) regioblock copolymers (<I>block</I>-P3HTs). These <I>block</I>-P3HTs consist of regioregular (<I>rre</I>) and regiorandom (<I>rra</I>) P3HTs, where the highly crystalline <I>rre</I> block allows efficient charge transport while the amorphous <I>rra</I> block provides mechanical robustness and interdomain connection. To examine the effects of the molecular architecture on the OTFT performance and stretchability, we prepare a series of <I>block</I>-P3HTs having different number-average molecular weight (<I>M</I><SUB>n</SUB>) values of <I>rra</I> blocks (from 0 to 32 kg mol<SUP>-1</SUP>) and a fixed <I>M</I><SUB>n</SUB> of <I>rre</I> blocks (11 kg mol<SUP>-1</SUP>). Thin films of all of the <I>block</I>-P3HTs exhibit a high charge-carrier mobility due to the formation of well-developed edge-on crystallites from the <I>rre</I> blocks confined within the <I>rra</I> domains, leading to a hole mobility of 1.5 × 10<SUP>-1</SUP> cm<SUP>2</SUP> V<SUP>-1</SUP> s<SUP>-1</SUP>, which is superior to that of the <I>rre</I> P3HT homopolymer. In addition, the mechanical toughness of <I>block</I>-P3HT thin films is remarkably enhanced by the <I>rra</I> block. While the <I>rre</I> P3HT homopolymer thin film shows a brittle behavior with an elongation at break of only 0.3%, the elongation at break of the <I>block</I>-P3HT thin films increases by a factor of 100, yielding 30.2% with increasing <I>M</I><SUB>n</SUB> of the <I>rra</I> block, without sacrificing the electrical properties. In particular, a noticeable enhancement of both elongation at break and toughness is observed between <I>M</I><SUB>n</SUB> values of the <I>rra</I> block of 8 and 20 kg mol<SUP>-1</SUP>, indicating that the critical molecular weight of <I>rra</I> P3HT plays an important role in determining the mechanical response of the <I>block</I>-P3HT thin films. This study provides guidelines and strategies to improve the mechanical properties of organic electroactive materials without the disruption of optoelectrical properties, which is critical to fabricate high-performance soft electronics.</P>
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