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In the past decade, tremendous progress has been made in organic field-effect transistors (OFETs). Their real applications require further development of device performance. OFETs consist of organic semiconductors, dielectric layers, and electrodes. Organic semiconductors play a key role in determining the device characteristics. The properties of the organic semiconductors, such as molecular structure and packing, as well as molecular energy levels, can be properly controlled by molecular design. Therefore, we designed and synthesized a series of organic molecules. The synthesized organic semiconductors exhibit excellent field-effect properties due to strong intermolecular interactions and proper molecular energy levels. Meanwhile, the influence of the device fabrication process, organic semiconductor/dielectric layer interface, and organic layer/electrode contact on the device performance was investigated. A deep understanding of these factors is helpful to improve field-effect properties. Furthermore, single-crystal field-effect transistors are highlighted because the single-crystal-based FETs can provide an accurate conducting mechanism of organic semiconductors and higher device performance as compared with thin film FETs. [ABSTRACT FROM AUTHOR]

We demonstrate modification of the indium tin oxide (ITO) surface with an ultrathin layer of hexadecafluorocopper phthalocyanine (F16CuPc) can significantly enhance hole injection as a result of the formation of an interfacial dipole layer. The dipole layer produces a surface potential shift, which reduces the hole injection energy barriers and thus improves the hole injection efficiency. The devices with anode modification exhibit significantly enhanced luminance efficiencies and dramatically decreased operation voltages, compared to devices with the bare ITO anode. The minimum turn-on voltage of 2.6 V and the maximum efficiency of 5.1 cd/A are achieved. [ABSTRACT FROM AUTHOR]

We present a method of fabricating noncoplanar channel organic field-effect transistors (OFETs) by a conventional photolithographic technique. Using this method, OFETs with micrometer critical features in slanting configurations and submicrometer critical features in vertical configurations were fabricated. The critical channel length over 1 μm was controlled by the patterning technique, while the one of 0.5 μm was defined by the thickness of an insulating layer between the drain and source electrodes. Also, we demonstrate that the OFETs containing two different metals as source and drain electrodes, respectively, are easily realized. All the OFETs based on copper phthalocyanine exhibit a high performance. [ABSTRACT FROM AUTHOR]

We report the effects of a metal chelate, bis[2-(2-hydroxyphenyl)benzothiazolate]zinc [Zn(BTZ)2] and 8-tris-hydroxyquinoline aluminum (Alq3) used as electron-transporting layers, and various cathodes on electroluminescent and current-voltage characteristics of a polymer light-emitting diode with phenyl-substituted poly(phenylene vinylene) as an emissive layer. We find that the metal chelate layers also play a role in hole blocking. For a double-layer device with the structure of indium-tin oxide (ITO)/polymer/Zn(BTZ)2 or Alq3/Al, the metal chelate layer lowers the hole current and improves the electroluminescent properties. Inserting a LiF layer between the metal chelate layer and the Al cathode enhances the electron injection and improves the elctroluminescent efficiency. The device with the structure of ITO/polymer/Zn(BTZ)2/Alq3/LiF/Al can reach the highest luminous efficiency of 5.0 cd/A. [ABSTRACT FROM AUTHOR]

The article discusses the research on the excellent electrical properties of low-cost organic transistors and inverters with chemical modified bottom electrodes. Study reveals, compatibility on energy of electrodes and organic semiconductors were important on forming a ohmic contact for efficient charge injection. However, semiconductors and gate dielectrics must be stable to prevent chemical reactions which could interfere.

One-dimensional (1D) nanostructures of the wide band gap semiconductors are promising building blocks for photoelectric nanodevices. However, some problems like strong 1D confinement largely hamper their applications. To avoid these problems, here, we provide another 1D configuration, in which an inner-wire coaxial Schottky junction exists, thus effectively avoiding the recombination of the photoexcited carriers. As an example, we produce ZnS/carbon nanotube nanocables with uniform morphologies by a two-step vapor deposition method and find that they have good conductance, obvious light response, and ohmic contacts with electrodes, avoiding the limitations of both the pristine nanomaterials. We believe that this configuration would be valuable for applying the 1D nanomaterials in photoelectronics. [ABSTRACT FROM AUTHOR]

Molecular electronics is often limited by the lack of a simple method to fabricate nanoelectrodes with controlled gap size. This is partly attributed to the lack of a real time characterization in the fabrication. Here, we report a new method based on an electron induced deposition process operated in scanning electron microscopy that realizes in situ and real time characterization in the nanoelectrode fabrication; thus the gap size can be controlled easily and precisely. It is a clean and nondestructive process for carbon nanotube (CNT) electrodes. The mechanism is detailed. The nanoelectrodes have a π-conjugated surface due to the deposition of sp 2-rich amorphous carbon. As an application, DNA molecules are assembled between the CNT electrodes by π-stacking interaction for current−voltage measurement. Our result provides a feasible route to prepare nanoelectrodes with controlled gap size, and it will be valuable for current efforts in molecular electronics and nanoelectronics. [ABSTRACT FROM AUTHOR]