Development and Characterization of Solution‐Processable Dithieno[3,2‐b : 2’,3’‐d]thiophenes Derivatives with Various End‐capped Groups for Organic Field‐Effect Transistors

Abstract

In this paper, four organic materials based on dithieno[3,2b : 2',3'-d]thiophene (DTT) core structure with end-capping groups (phenyl and thienyl) and linker (acetylenic and olefinic) between DTT-core and end-capping groups were synthesized and characterized as solution-processable organic semiconductors (OSCs) for organic field-effect transistors (OFETs). Thermal, optical, and electrochemical properties of the corresponding materials were determined. Next, all DTT-derivatives were coated by solution-shearing method, and the thin-film microstructures and morphologies were investigated. To investigate the electrical performance of four newly synthesized DTTderivatives, bottom-gate/top-contact OFETs were fabricated and characterized in ambient condition. It was found that substitution of acetylenic for olefinic linkers between DTT-cores and end-capping groups enhanced device performance. Especially, the resulting OFETs based on the compound containing phenylacetylene exhibited the highest hole mobility of 0.15 cm 2 /Vs and current on/off ratio of ~10 6 , consistent with film morphology and texture showing long range interconnected crystalline grains and strong diffraction peaks.

Characterization of [1]Benzothieno[3,2-b]benzothiophene (BTBT) Derivatives with End-Capping Groups as Solution-Processable Organic Semiconductors for Organic Field-Effect Transistors

“…Furthermore, in some cases, they could prevent side reactions such as oxidation and polymerization, while affording ambient stability and promoting dense molecular packing [35]. Several researchers have also demonstrated that attaching olefinic or acetylenic linkage between core and functional groups to the molecules is beneficial for the extension of π-conjugation length and the optimization of planar structures [36][37][38][39][40][41][42][43][44][45]. In particular, the introduction of acetylenic linkage showed multiple advantages such as higher oxidation potential and lower highest occupied molecular orbital (HOMO) from the weak electron withdrawing nature of the corresponding group [38,43,46].…”