Quinoidal bisthienoisatin based semiconductors: Synthesis, characterization, and carrier transport property

• Published in: Nano select 2020-09, Vol.1 (3), p.334-345
• Main Authors: Kohara, Akihiro, Hasegawa, Tsukasa, Ashizawa, Minoru, Hayashi, Yoshihiro, Kawauchi, Susumu, Masunaga, Hiroyasu, Ohta, Noboru, Matsumoto, Hidetoshi
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Carrier transport; Conducting polymers; conductive state of polymer; crystal structure; Current carriers; delocalized piflamework; Design; Energy; Energy gap; Molecular structure; near‐infrared light absorbing property; Oxidation; Phase transitions; Polymers; quinoidal bisthienoisatin; Semiconductors; Single crystals; Structural analysis; Temperature; Thin films; Transport properties
• ISSN: 2688-4011; 2688-4011
• DOI: 10.1002/nano.202000053

Novel quinoidal bisthienoisatin (QBTI) derivatives end‐capped with phenyl and thienyl groups were designed and synthesized. Single‐crystal X‐ray structure analysis of phenyl group flanked QBTI molecule confirmed that the quinoidal structure contributed to the high planarity of the molecular skeleton and the construction of one‐dimensional stacks. The quinoidal form of bisthienoisatin derivatives displayed ambipolar carrier transport properties with mobilities of approximately 10−4 cm2 V−1 s−1. Different flanking aromatic rings considerably affected the thin‐film microstructure and hence the charge carrier transport properties of the material. The QBTI‐based narrow energy gap polymers were theoretically designed and synthesized. Delocalized quinoidal resonance of QBTI unit along the polymer backbone is of particular importance to achieve relatively high conductive state (10−3 S cm−1). We demonstrate that QBTI cores should be promising building blocks for constructing narrow energy gap semiconducting and conductive polymers. In the quest of new building block comprising organic semiconductors, quinoidal bisthienoisatin (QBTI) unit have been developed. QBTI‐based small molecules exhibited ambipolar carrier transport coming from narrow energy gap. It is noteworthy that QBTI based polymer composed with thienoisoindigo unit displayed relatively high conductive state (10−3 S cm−1) well associated with near‐infrared (NIR) light absorbing property.