Regioisomeric control of layered crystallinity in solution-processable organic semiconductors

Inoue, Satoru; Higashino, Toshiki; Arai, Shunto; Kumai, Reiji; Matsui, Hiroyuki; Tsuzuki, Seiji; Horiuchi, Sachio; Hasegawa, Tatsuo

doi:10.1039/d0sc04461j

Cited by 29 publications

(48 citation statements)

References 83 publications

(93 reference statements)

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“…In OSCs, alkyl chain substitutions of π-cores are often used to increase the solvent solubility, which is an indispensable function for their application in printed electronics technology. − It was recently demonstrated that one-sided unsymmetric substitutions of π-cores with long alkyl chains enable the formation of a unique bilayer-type LHB (b-LHB) packing, which considerably enhances the layered crystallinity. − These effects have been revealed with several compounds, such as [1]benzothieno[3,2- b ][1]benzothiophene (BTBT), − benzothieno[3,2- b ]naphtho[2,3- b ]thiophene (BTNT), ,, and benzo[1,2- b :4,5- b ]bis[ b ]benzothiophene (BBBT) derivatives. The adjacent intermolecular interactions between the alkyl chains stabilize the layered molecular packing.…”

Section: Introductionmentioning

confidence: 99%

“…The flexible nature of the alkyl chains probably contributes to enhancing the layered crystallinity by complementing the 2D ordering of rigid π-cores. The substituted alkyl chains usually form all-trans conformations in the layered crystals and their stretching direction from the π-core is variable, which enables the formation of alkyl chain layers that are adaptable to the alignment of the π-core layers. ,,, …”

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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The control of two-dimensional layered crystalline and/or liquid crystalline phases for π-extended organic molecules is crucial for expanding the potential of organic electronic materials and devices. In this work, we develop unique solution-processable organic semiconductors based on the unsymmetric substitution of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) with two different substituents, namely, phenylethynyl (PE) and normal alkyl with different chain lengths n (−C n H2n+1), both of which exhibit structural flexibility while maintaining the rod-like nature over the entire molecule. A distinctive layered solid crystalline phase, analogous to the smectic liquid crystalline phase, is obtainable in PE-BTBT-C n at n = 6, where the substituent lengths are almost the same. The BTBT moiety maintains a rigid layered-herringbone (LHB) packing, whereas the molecular long axis exhibits a complete orientational disorder. We refer to this packing as disordered LHB (d-LHB), the unique geometry of which can be analyzed by the emerging technique of microcrystal electron diffraction crystallography. The intermolecular core–core interactions stabilize the d-LHB packing, enabling a relatively high field-effect mobility of approximately 3 cm2 V–1 s–1. In contrast, PE-BTBT-C n with longer alkyl chains (n = 8, 10, 12) exhibits higher mobility of approximately 7 cm2 V–1 s–1 by constituting bilayer-type LHB (b-LHB), which is associated with the unsymmetrical length of the substituents. We discuss the correlation and competition among the d-LHB, b-LHB, and smectic liquid crystalline phases based on the structural, thermal, and transistor characteristics. These findings demonstrate the controllability of various phases in layered organic semiconductors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2021

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“…Alkyl substituents also affect other critical characteristics of organic semiconductors such as solution processability and molecular packing motif (e.g., brickwork vs herringbone). These alkyl group effects are generally subtle and hard to predict; therefore, molecular design of organic semiconductors often involves experimental screening of structures and positions of alkyl substituents. ,− …”

Section: Introductionmentioning

confidence: 99%

Exploration of Alkyl Group Effects on the Molecular Packing of 5,15-Disubstituted Tetrabenzoporphyrins toward Efficient Charge-Carrier Transport

Jeong

Itô

Takahashi

et al. 2022

ACS Appl. Mater. Interfaces

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The high design flexibility of organic semiconductors should lead to diverse and complex electronic functions. However, currently available high-performance organic semiconductors are limited in variety; most of p-type materials are based on thienoacenes or related one-dimensionally (1D) extended π-conjugated systems. In an effort to expand the diversity of organic semiconductors, we are working on the development of tetrabenzoporphyrin (BP) derivatives as active-layer components of organic electronic devices. BP is characterized by its large, rigid two-dimensionally (2D) extended π-framework with high light absorptivity and therefore is promising as a core building unit of organic semiconductors for optoelectronic applications. Herein, we demonstrate that BP derivatives can afford field-effect hole mobilities of >4 cm2 V–1 s–1 upon careful tuning of substituents. Comparative analysis of a series of 5,15-bis(n-alkyldimethylsilylethynyl)tetrabenzoporphyrins reveals that linear alkyl substituents disrupt the π–π stacking of BP cores, unlike the widely observed “fastener effect” for 1D extended π-systems. The n-octyl and n-dodecyl groups have the best balance between high solution processability and minimal π–π stacking disruption, leading to superior hole mobilities in solution-processed thin films. The resulting thin films show high thermal stability wherein the field-effect hole mobility stays above 1 cm2 V–1 s–1 even after heating at 160 °C in air, reflecting the tight packing of large BP units. These findings will serve as a good basis for extracting the full potential of 2D extended π-frameworks and thus for increasing the structural or functional diversities of high-performance organic semiconductors.

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“…It was recently shown that the layered crystallinity is enhanced by elaborate end-cap substitutions of some extended π-cores. − One-sided alkyl chain substitution allowed the formation of a bilayer-type layered herringbone ( b -LHB) packing, which clearly enhanced the layered crystallinity. , In the b -LHB packing, unidirectionally oriented monomolecular layers were formed, in which the alkyl chains played essential roles in architecting the layered molecular assembly. Furthermore, the other-sided end-capping with a phenyl group may have assisted in the formation of the b -LHB packing, , probably by suppressing the long-axis molecular slip.…”

Section: Introductionmentioning

confidence: 99%

Architecting Layered Crystalline Organic Semiconductors Based on Unsymmetric π-Extended Thienoacenes

et al. 2021

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Herein, we demonstrate that engineered end-cap substitution for unsymmetric extended π-cores effectively achieves well-ordered two-dimensional (2D) molecular packing and thus realizes high-performance organic semiconductors (OSCs). We developed phenyl- and decyl-substituted benzothieno[6,5-b]benzothieno[3,2-b]thiophenes (BTBTTs) as solution-processable OSCs, providing layered single-crystalline thin-film transistors with a hole mobility of up to 12 cm2 V–1 s–1. The compound formed a bilayer-type layered herringbone packing in which the unsymmetric π-core aligned unidirectionally to form the respective molecular layers, owing to the well-balanced contributions of intermolecular interactions between the π-cores and between the respective end substituents. The eventual close intralayer molecular packing afforded a small effective mass and high thermal stability. These findings will be crucial for expanding the ability to develop high-performance OSCs.

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Regioisomeric control of layered crystallinity in solution-processable organic semiconductors

Abstract: Construction and control of 2D layered molecular packing motifs with functionally substituted π-electron cores are crucial for developing organic electronic materials and devices. We investigated a regioisomeric structure–property relationship in...

Cited by 29 publications

References 83 publications

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

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

Exploration of Alkyl Group Effects on the Molecular Packing of 5,15-Disubstituted Tetrabenzoporphyrins toward Efficient Charge-Carrier Transport

Architecting Layered Crystalline Organic Semiconductors Based on Unsymmetric π-Extended Thienoacenes

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