Advantage of arch-shaped structure on transistor performances over linear-shaped structure in dibenzothienopyrrole semiconductors
摘要:
To understand the influence of molecular shape on the optoelectronic properties of heteroacenes, we report here the syntheses and characterizations of two linear- and two arch-shaped dibenzothienopyrrole (DBTP) derivatives, namely, N-hexyldibenzothieno[3,2-b:2',3'-d]pyrrole (l-HDBTP), N-phenyldibenzothieno[3,2-b:2',3'-d] pyrrole (l-PDBTP), N-hexyldibenzothieno[2,3-b:3',2'-d]pyrrole (a-HDBTP) and N-phenyldibenzothieno[2,3-b:3',2'-d]pyrrole (a-PDBTP). Their structure-property relationships have been systematically studied by optical absorption, cyclic voltammetry, single-crystal X-ray diffraction analyses and the single-crystal-based and thin-film-based field-effect transistors (FETs). The results demonstrate that the arch-shaped DBTP derivatives can modify their electronic structures and molecular arrangements by tuning of substituents, to obtain a better charge-transporting ability relative to the linear-shaped ones. The arch-shaped N-phenyl substituted a-PDBTP exhibits optimum molecular pi-stacking arrangement and charge transport properties, with the hole mobility of 0.75 cm(2)V(-1)s(-1) and 0.058 cm(2)V(-1)s(-1) for the single-crystal and the thin-film OFETs, respectively. These results indicate that the arch-shaped DBTP core is a promising building block in the area of organic semiconducting materials.
K<sub>2</sub>S<sub>2</sub>O<sub>8</sub>-mediated radical cyclisation of 2-alkynylthioanisoles or -selenoanisoles: a green and regioselective route to 3-nitrobenzothiophenes and benzoselenophenes
An acid, transition-metal, and chromatography-free radical nitration/cyclisation of 2-alkynylthioanisoles or -selenoanisoles has been developed. This is the first example of the use of highly unstable 2-nitrovinyl radicals for C–S bond formation. This facile route efficiently produces 3-nitrobenzothiophenes and benzoselenophenes, which are difficult to access via classical methods. Density functional