Development of high-performance printed semiconductor devices is highly desired with the expectation for the nextgeneration technologies of "printable electronics" providing simply fabricated, fl exible, large-area, low-cost, and environmentally friendly electronic products such as paper-like fl exible displays. Patterned arrays of printed organic fi eld-effect transistors (OFETs) based on chemically stable solutionprocessed organic semiconductors are regarded as key devices that operate as fundamental switching components in, for example, pixel-controlling active-matrix elements. However, performance of conventional solution-coated noncrystal organic thin-fi lm transistors has yet to be improved for practical use in general electronic circuitry. Here, newly developed arrays of patterned crystalline OFETs of air-stable compound 2,9-didecyl-dinaphtho[2,3-b:2',3'-f ]thieno[3,2-b]thiophene (C 10 -DNTT) formed from hot solution are presented. A method of oriented growth is introduced to provide the singlecrystalline fi lms of C 10 -DNTT that regulates the crystallizing direction and positions in a single process. The benchmark value, 10 cm 2 V − 1 s − 1 , of the charge mobility is achieved for the present OFETs, far exceeding the performance of former devices and opening a practical way to realize printed and fl exible electronics with suffi cient switching speed. The result is attributed to almost perfect molecular periodicity in the crystal fi lms, which allows effective intermolecular charge transport of the electrons.In the process of forming organic semiconductor fi lms from solution by naturally evaporating the solvent near room temperature, constituent molecules that are independently dispersed in the solvent, are expected to self-organize into a highly ordered assembly with the amazing speed of more than 10 10 molecules per second. [ 1 ] Since the speed of the fi lm growth is directly translated to high-throughput production, solution techniques such as spin-coating and drop-casting are very attractive for the industry. [ 2 ] Regarding the performance of the solution-processed organic fi eld-effect transistors (OFETs), their switching speed is directly determined by charge carrier mobility in the organic semiconductors, which relies on microscopic electronic properties of molecule-to-molecule charge-transfer probability and the extent of molecular ordering. Therefore, it has been intensively challenging to create high-mobility active semiconductor layers using simple solution techniques. In addition, simple methods of forming their patterned arrays during the fi lm growth have been regarded as essential technology for accelerated production of matrix devices. Here, the extent of the molecular order signifi cantly infl uences device performance through the charge carrier mobility in the semiconductor fi lms. In order to realize much higher performance than achieved in present devices, synthesis of functional π -conjugated molecules with superior selfassembling properties, in addition to their high-charge-trans...

Organic thin-fi lm transistors (OTFTs) have attracted great interest for their potential use in several electronic applications, including active-matrix displays, electronic paper, and chemical sensors. [ 1 ] Among the many semiconducting materials evaluated in the TFT confi guration, pentacene is the best as it shows the highest fi eld-effect mobility ( > 3.0 cm 2 V − 1 s − 1 ). [ 2 , 3 ] On the other hand, new organic semiconductors are being actively investigated to further improve the performance of OTFTs. In fact, superior unconventional organic semiconductors used to produce high-performance OTFTs have been recently reported, including picene (3.2 cm 2 V − 1 s − 1 ), [ 4 ] [ 6 ] and hexamethylene-tetrathiafulvalene (HMTTF, 6.9 cm 2 V − 1 s − 1 . [7] We have also developed several new heteroarenebased organic semiconductors that show high mobility in the TFT confi guration: 2,7-diphenyl[1]benzothieno[3,2-b ]benzothiophene (DPh-BTBT, 2.0 cm 2 V − 1 s − 1 ), [ 8 ] dinaphtho[2,3-b :2 ′ ,3 ′ -f ] thieno[3,2-b ]thiophene (DNTT, 2.9 cm 2 V − 1 s − 1 ), [ 9 ] and alkylatedBTBTs (C n -BTBTs, 3.9 cm 2 V − 1 s − 1 ). [ 10 ] Intrinsically, carrier transport in organic molecular solids is governed by the extent of intermolecular orbital coupling (transfer integrals), where larger orbital coupling can afford higher mobility. [ 11 ] One of the promising approaches to enhance orbital coupling is to use highly π -extended molecules: high-performance OTFTs based on picene, DTTE, or DNTT [ 12 ] that have highly π -extended structure are an example. Another effective approach is to use the self-organizing nature of organic molecules: this is exemplifi ed by DTBDT or C n -BTBTbased OTFTs, in which long alkyl groups can act as the driving force for molecular ordering in the solid state owing to the van der Waals intermolecular interaction between the alkyl groups, or the so-called molecular fastener effect, [ 13 ] that renders the semiconducting core to pack tightly, thereby enhancing carrier mobility. With these molecular design strategies for enhancing TFT performance, we focused on alkylated DNTTs (C n -DNTTs, Scheme 1 ) as new promising molecular semiconductors. In this paper, we report their synthesis, characterization, and OTFT devices that show very high fi eld-effect mobility close to 8.0 cm 2 V − 1 s − 1 .The syntheses of C n -DNTT ( n = 6, 8, 10, 12) were carried out with the same strategy as that for the parent DNTT. Starting from 6-alkyl-2-naphthaldehyde, introduction of methylthio moiety at the 3-position via the selective o -lithiation with lithium N,N,N ′ -trimethylethylenediamide and excess n-BuLi gave 3-methylthio-6-alkyl-2-naphthaldehyde in moderate yields. Low-valent titanium-mediated dimerization of the aldehyde functionality readily gave the olefi ne precursor, which was fi nally converted into C n -DNTTs in moderate to good yields via the idodine-promoted ring closing reaction (Scheme 1 ).[ 9 ] C nDNTTs are stable yellow compounds and their characterization was accomplished by spectroscopic and combustion ...

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A new straightforward synthesis of dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) derivatives from readily available 2-methoxynaphthalenes is described. Thus, newly developed derivatives of DNTT showed very high field effect mobility in the vapor-processed field-effect transistors up to 8 cm(2) V(-1) s(-1).

Low-voltage p-channel and n-channel organic transistors with channel lengths down to 0.5 μm using four small-molecule semiconductors and ultra-thin dielectrics based on two different phosphonic acid monolayers are fabricated on plastic substrates and studied in terms of effective mobility, intrinsic mobility and contact resistance. For the optimum materials combination, flexible complementary circuits have signal delays of 3.1 μs at 5 V.