Molecularly aligned films of [1]benzothieno[3, 2‐b][1]benzothiophene derivatives by solution shearing: Effect of alkyl substitution on morphology and charge transporting property. Issue 3 (25th January 2022)

• Record Type: Journal Article
• Authors: Prakoso, Suhendro Purbo; Ke, Yao‐Jin; Huang, Ding‐Chi; Wang, Chien‐Lung; Tao, Yu‐Tai
• Is Part Of: Journal of the Chinese Chemical Society. Volume 69:Issue 3(2022)
• Page Start: 440
• Page End: 449
• Publication Date: 2022-01-25
• Subjects: 2D organic semiconductors -- conjugated small molecules -- GIWAXS -- solid‐state morphology; Chemistry -- Periodicals; Electronic journals; 540.5
• DOI: 10.1002/jccs.202100531
• Languages: English
• ISSNs: 0009-4536

Abstract

Abstract: The self‐assembly behaviors, crystal morphologies, and charge transporting properties of π–conjugated framework can be strongly affected by the functional group/substituent it carries, as well as the way the film is prepared. In this work, thin films of mono‐ and di‐alkylated [1]benzothieno[3, 2‐b][1]‐benzothiophene (BTBT) derivatives were prepared on a silicon substrate by solution‐shearing method. Their film morphologies and crystal packing details were examined using polarized optical microscope, grazing incident wide‐angle X‐ray scattering, and atomic force microscope. With 2‐tridecyl[1]benzothieno[3, 2‐b][1]‐benzothiophene (C13‐BTBT ), a film with well‐aligned molecules packed in face‐to‐face π‐stacking arrangement was obtained, rendering a 1D‐like charge conduction channel. For 2, 7‐bis‐tridecyl[1]benzothieno[3, 2‐b][1]‐benzothiophene (C13‐BTBT‐C13 ), well‐aligned molecules packed in a layered‐herringbone arrangement were obtained. With these films as a conducting channel in transistor fabrication, high‐field‐effect mobility was realized for C13‐BTBT‐C13, with a maximum mobility (μh ) of 0.645 cm 2 /Vs and low anisotropic effect, presumably owing to the 2D growth of the π–conjugated skeleton in LHB packing. This study demonstrated the advantage of 2D semiconducting channels formed from C13‐BTBT‐C13 by low‐cost and scalable solution‐shearing processes, necessary for practical use in industry‐level and future flexible electronics. Abstract : Well aligned films of BTBT derivatives carrying one or two long alkyl side chains can be prepared by solution‐shearing method. Different crystal packing modes were obtained for the two. The layered‐herringbone and thus 2D‐like arrangement obtained for disubstituted BTBT gave a highest mobility of 0.645 cm 2 /Vs, with low anisotropy. The monosubstituted BTBT gave 1D π‐π packing and lower but anisotropic mobility of 0.05 cm 2 /Vs.