Emerging Disordered Layered-Herringbone Phase in Organic Semiconductors Unveiled by Electron Crystallography

• DOI: 10.1021/acs.chemmater.1c02793
• Publication Date: 2021-12-22T17:02:22Z
• Authors: Satoru Inoue; Kiyoshi Nikaido; Toshiki Higashino; Shunto Arai; Mutsuo Tanaka; Reiji Kumai; Seiji Tsuzuki; Sachio Horiuchi; Haruki Sugiyama; Yasutomo Segawa; Kiyofumi Takaba; Saori Maki-Yonekura; Koji Yonekura; Tatsuo Hasegawa
• Keywords: Organic semiconductor; Moiety; Side chain

The control of two-dimensional layered crystalline and/or liquid phases for π-extended organic molecules is crucial expanding the potential electronic materials and devices. In this work, we develop unique solution-processable semiconductors based on unsymmetric substitution [1]benzothieno[3,2-b][1]benzothiophene (BTBT) with two different substituents, namely, phenylethynyl (PE) normal alkyl chain lengths n (−CnH2n+1), both which exhibit structural flexibility while maintaining rod-like nature over entire molecule. A distinctive solid phase, analogous to smectic obtainable in PE-BTBT-Cn at = 6, where substituent are almost same. BTBT moiety maintains a rigid layered-herringbone (LHB) packing, whereas molecular long axis exhibits complete orientational disorder. We refer packing as disordered LHB (d-LHB), geometry can be analyzed by emerging technique microcrystal electron diffraction crystallography. intermolecular core–core interactions stabilize d-LHB enabling relatively high field-effect mobility approximately 3 cm2 V–1 s–1. contrast, longer chains (n 8, 10, 12) higher 7 s–1 constituting bilayer-type (b-LHB), associated unsymmetrical length substituents. discuss correlation competition among d-LHB, b-LHB, structural, thermal, transistor characteristics. These findings demonstrate controllability various semiconductors.