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Very high-mobility organic transistors are fabricated with purified rubrene single crystals and high-density organosilane self-assembled monolayers. The interface with minimized surface levels allows carriers to distribute deep into the crystals by more than a few molecular layers under weak gate electric fields, so that the inner channel plays a significant part in the transfer performance. With the in-crystal carriers less affected by scattering mechanisms at the interface, the maximum transistor mobility reaches 18cm2∕Vs and the contact-free intrinsic mobility turned out to be 40cm2∕Vs as the result of four-terminal measurement. These are the highest values ever reported for organic transistors.

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...

In frustrated magnetic systems, long-range ordering is forbidden and degeneracy of energy states persists, even at extremely low temperatures. Under certain conditions, these systems form an exotic quantum spin-liquid ground state, in which strongly correlated spins fluctuate in the spin lattices. Here we investigate the thermodynamic properties of an anion radical spin liquid of EtMe3Sb[Pd(dmit)2]2, where dmit represents 1,3-dithiole-2-thione-4,5-dithiolate. This compound is an organic dimer-based Mott insulator with a two-dimensional triangular lattice structure. We present distinct evidence for the formation of a gapless spin liquid by examining the T-linear heat capacity coefficient, γ , in the low-temperature heat capacity. Using comparative analyses with κ-(BEDT-TTF)2Cu2(CN)3, a generalized picture of the new spin liquid in dimer-based organic systems is discussed. We also report anomalous enhancement of γ, produced by a kind of criticality inherent to the Pd(dmit)2 phase diagram.