Organic Single-Crystal Transistors Based on π-Extended Heteroheptacene Microribbons

Abstract

Facile synthesis of a new series of ³-extended thienoacenes has been described. Their electronic structures have been elucidated by UVvis absorption and photoelectron spectra. Well-defined single-crystal microribbons composed of self-organized thienoacene molecules have been fabricated using physical vapor transport, and have been applied to field-effect transistors. The organic transistors employing the single-crystal microribbons exhibit mobilities as high as 0.47 cm 2 V s ¹1 with on/off ratios of ca. 10 6 .Due to the rapid progress in organic electronics, the development of high-performance organic semiconductors continues to be a crucial area of research.1,2 Organic field-effect transistors (OFETs) have attracted great interest, 2,3 as a low-cost alternative to traditional silicon transistors for their use in electronics applications, including active-matrix displays, circuits, and radio-frequency identification (RFID) devices. 4 The design and synthesis of novel ³-conjugated materials with comprehensively excellent properties and sophisticated self-organized structures are major challenges to enhance the OFET performance.Compared with OFETs based on organic thin films, those using organic single crystals (e.g., pentacene and rubrene) can produce significantly enhanced carrier transport functionality on account of their near-perfect molecular order and defect-free morphologies.5 Recently, high-performance OFETs have successfully been demonstrated using one-dimensional (1D) nanoor microsized organic crystalline materials. 6 One can expect that the construction of linearly ³-extended oligoacene structures leads to further enhancement of intermolecular ³-orbital overlap (or transfer integrals) and carrier transport properties of the materials. Nevertheless, so far, there are only a few reports on stable ³-conjugated oligoacenes with more than six fused rings as organic semiconductors.7 Moreover, most of these materials still suffer from a complicated synthesis and bothersome purification processes.We herein disclose the facile synthesis, photophysical properties, self-organization, and OFET properties of sevenring-fused ³-extended thienoacenes (Figure 1 Results and DiscussionSynthesis and Characterization. The synthetic procedures used to prepare new thienoacenes are outlined in Scheme 1 (see Experimental for details). The SuzukiMiyaura cross-coupling reactions between 1,4-dibromo-2,5-bis(methylsulfinyl)benzene (1) and the corresponding boronic acids with [Pd(PPh 3 ) 4 ] as a catalyst afforded key precursors 24 in 7380% yields. Compounds 24 having methylsulfinyl groups were subsequently converted into TTBDT, BTBDT, and BFBDT, respectively, in 6795% yields, via intramolecular double cycliza-

Synthesis of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and its higher homologs through palladium-catalyzed intramolecular decarboxylative arylation

“…The physical properties of BBTBDT have been reported. 7,8 Using 1c and 2b could also be obtained 2,9-dioctyl-BBTBDT (2C 8 -BBTBDT), albeit with a moderate yield. 14…”

“…7 BBTBDT was also prepared by a Pummerer-type biscyclization. 8 Recently, Takimiya and coworkers disclosed an elegant process for the construction of BTBT as well as its higher homologs by the sequential reactions of 2[2-(trimethylsilyl)ethynyl]thioanisole with PhSCl to form the corresponding 3-(phenythio)benzo [b]thiophene and its 2-bromination followed by palladium-catalyzed intramolecular C-H arylation. 9 Despite these achievements for constructing the BTBT series of compounds, there still remains a substantial demand for further development of effective and flexible synthetic methods to enhance their utility.…”

Organic Semiconductors for Field-Effect Transistors

“…Moreover, with 6,13-pentacenequinone films as gate insulators BGTC; Au;SiO 2 /Si; OTS [84] (continued) (continued) BGTC; Au; SiO 2 /Si; PMMA [134] (continued) (continued) (continued) [198] (continued) [63]. However, because of the narrow energy gap and high-lying HOMO energy level, pentacene exhibited high sensitivity to light and high oxidation sensitivity to oxygen [64].…”

Evaluation of the intrinsic charge carrier transporting properties of linear- and bent-shaped π-extended benzo-fused thieno[3,2-b]thiophenes

“…Due to their utility as active layer materials in organic field-effect transistors (OFETs), a huge number of compounds have been developed by many research groups through elaborate synthetic approaches. In 2014, we demonstrated the new synthetic pathways to access 7-ring thienoacene derivatives using palladiumcatalyzed coupling reactions, where both linear-and bent-shaped isomers, BBTBDT 8,9 and iso-BBTBDT (Fig. In 2014, we demonstrated the new synthetic pathways to access 7-ring thienoacene derivatives using palladiumcatalyzed coupling reactions, where both linear-and bent-shaped isomers, BBTBDT 8,9 and iso-BBTBDT (Fig.…”