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We prepared a large quantity of multiwall nanotubes with intramolecular junctions (CNx/C) by pyrolysis of iron phthalocyanine with or without an inlet of ammonia gas. The nanotubes consist of two sections, one section made of carbon nitride featuring bamboo-like structure and the other one made of carbon featuring empty hollow cylinder structure, and thus the intramolecular junctions were formed in the middle as a result of being doped or undoped with nitrogen. Nanodiode based on a single CNx/C junction shows reproducible rectifying behavior with a rectification ratio of 1.3×103 at ±2 V. In addition, the nanodiode demonstrated as a half-wave rectifier worked at an input sine wave of 1 kHz. Two CNx/C junctions were configured together to exhibit functions of OR and AND logic gates. Moreover, after substituting the wave-detection silicon diode in common transistor radio set with our nanodiode, the radio set still worked normally, representing an important step toward the potential application for nano-scale devices.

Field-effect transistors (FETs) based on an individual CNx/C nanotube (NT) were fabricated by focus ion-beam technology. The nanotube transistors exhibited n-type semiconductor characteristics, and the conductance of nanotube FETs can be modulated more than four orders of magnitude at room temperature. The electron mobility of a CNx/C NT FET estimated from its transconductance was as high as 3.84×103 cm2/V s. The n-type gate modulation could be explained as due the effect of bending of the valence band in the Schottky-barrier junction.

Thin-film transistors based on aligned carbon nanotubes (CNTs) were fabricated by directly growing highly ordered CNTs on silicon dioxide surface. The transistor shows a pronounced field effect. Electric transport through the aligned carbon nanotubes is dominated by the holes at room temperature. A hole mobility (μp) of the CNT thin-film transistor was estimated to be as high as 61.6 cm2/V s. Such a mobility is comparable to that of heavily doped n-Si and is larger than individual CNT field-effect transistor. Thus, it reveals a potential application of the aligned CNTs in electronics.

The solubility of fullerene (C60) is improved by combining it with an alkyl group of substituted copper (II) phthalocyanine (CuPc) through Diels–Alder reaction. Optical limiting properties of this compound were investigated by using a double frequency Nd:YAG laser system at a wavelength of 532 nm with pulse duration of 45 ps. The results show that there are two separated conjugation systems in this kind of molecule. Both of them independently contribute to the reverse saturable absorption. Broadband optical limiting materials might be designed based on the combination of various optical limiting molecules through covalent bonds. Phase separation problems existing in the mixture of various materials can be avoided.

We report an efficient electroluminescent device using a binaphthalene-containing polymer as the emissive layer and a fluorinated copper phthalocyanine as the electron injecting/transporting layer. The structural feature of this polymer is a twisted, nonplanar backbone with two hexyloxy side groups. The energy levels for the highest occupied molecular orbital and the lowest unoccupied molecular orbital of this polymer were −5.71 and −2.38 eV as determined by cyclic voltammetry and ultraviolet-visible measurements. A light-emitting diode with aluminum electrode exhibited high brightness (9400 cd/m2 at 24.3 mA/cm2), excellent luminous efficiency (4.9 lm/W), and a large external quantum efficiency (2.0%).

The optical and electroluminescence properties of a light-emitting poly(arylene vinylene) derivative comprising triphenylamine as the arylene unit (TPA–PPV) are demonstrated. TPA–PPV is soluble in common organic solvents, and has a high photoluminescent (PL) quantum yield (ΦPL=0.94 in benzene). A single-layer light-emitting diode Indium–tin–oxide/TPA–PPV/Al utilizing blue–green light-emitting TPA–PPV as the emissive layer is fabricated, and luminance in excess of 612 cd/m2, turn-on voltages of 1.5 V, and high luminous efficiency (3.0 lm/w) are reported.

From the velocity of sound measurements, obtained using Brillouin scattering and ultrasound techniques, the elastic and piezoelectric coefficients of lithium triborate (LiB3O5; LBO) single crystals have been determined. Based upon the sound propagation equations and above results, the slowness curves in (100), (010), and (001) crystalline planes are calculated and presented. Some properties of sound propagation and electromechanical coupling in the crystal are also discussed.

Bottom-gate bottom-contact (BGBC) organic thin film transistors (OTFTs) based on N,N′-ditridecyl perylene diimide exhibit electron mobility as high as 3.54 cm2 V−1 s−1 in nitrogen, higher than that (1 cm2 V−1 s−1) of bottom-gate top-contact devices. The better performance of BGBC configuration in N2 is attributed to lower contact resistance, which is further reduced by thermal annealing. After thermally annealing the BGBC OTFTs at 180 °C, electron mobility as high as 3.5 cm2 V−1 s−1, current on/off ratio of 106 and threshold voltage of 9 V are achieved in air, and the mobility retains above 1 cm2 V−1 s−1 after storage for two months in air. Thermal treatment enhanced crystalline grains, reduced grain boundaries, and suppressed the adsorption of H2O and O2, leading to excellent performance in air.

Polarized photoluminescence spectra of the nonpolar ZnO single crystals annealed at different temperatures in air were investigated, for which the whole emission spectra from visible up to ultraviolet range for zinc and oxygen defects states are taken separately via the parallel and the crossed polarization geometries, respectively. It is also deduced from the spectra that the density of oxygen vacancy defects attains minimum for the sample annealed at 400 °C, and above which both anharmonic effects of ultraviolet emission and enhancement of defect-related deep band emission band due to the increase of oxygen and zinc vacancy defects are observed.

Polarized Raman spectroscopy has been performed to investigate the effects of the electric field on 0.67PbMg1/3Nb2/3O3–0.33PbTiO3 (PMN–33%PT) single crystal. The electric-field-evolution of Raman spectra differed from one microarea to another. In the crossed polarization geometry, the abrupt changes in the intensities of the Raman bands at around 570 and 780 cm−1 indicated the occurrence of the field induced phase transition from the MC-type to the MA-type monoclinic structure. On the other hand, the Raman spectra for the microarea that was initially in the MA phase exhibited no obvious changes. All these results revealed the microheterogeneity in PMN–33%PT single crystal, which is useful for understanding the field-induced superior electromechanical properties.

The authors reported organic phototransistors (PTs) with octadecyltrichlorosilane treated SiO2/Si substrate based on anthra[2,3-b]benzo[d]thiophene. The organic PTs show a high mobility of 0.4 cm2 V−1 s−1, a maximum photoresponsivity of about 1000 A/W, and photocurrent/dark-current ratio of around 800 under white light irradiation with 30 μW/cm2. The data are comparable with those of PTs based on amorphous silicon. Meanwhile, it is interesting to see that the devices show a high air-stable property and high photosensitivity via electric-field enhanced process. All these phenomena were attributed to the intrinsic optic-electronic property of the organic semiconductor and optic-electric field effect.

Highly photosensitive nanoswitches with a structure of indium tin oxide/organic insulator/metal have been fabricated. Electric current in the photoswitches is sensitive to ultraviolet (UV) radiation, and can be inhibited and recovered by exposing the photoswitch to, or shielding it from, UV radiation, respectively. Photoswitches with a very high on/off ratio exceeding 106, which is the highest ratio recorded for all reported organic photoswitches, have been demonstrated under UV radiation even with a low power density (∼10−5W∕cm2).

The aim of this study is to establish the structure-properties relationship of tetrathiafulvalene (TTF). After this study (1) TTF crystals with α and β phases were controllably obtained by the cast method with careful selection of the solvents, and (2) organic field-effect transistors (OFETs) of α and β phases both exhibited field-effect performance, and the performance of α phase was much better than that of β phase. The highest mobility of α phase reached 1.2cm2V−1s−1, while β phase showed the maximum mobility only about 0.23cm2V−1s−1, indicating the strong performance dependence of OFETs performance on the crystal phases.

The authors report a simple approach to reduce power consumption of organic light-emitting diodes. Introducing a 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline layer into the emissive layer can dramatically improve the carrier recombination efficiency. The presence of an interlayer of tris(8-quinolinolato)aluminum (Alq3) within the hole-transport layer also gives rise to the similar phenomenon. Furthermore, they modified the anode with the ultrathin hexadecafluorocopper phthalocyanine layer in order to further enhance the electroluminescent properties. They obtained the high performance light-emitting diodes using Alq3 as the emissive layer with a high current efficiency of 7.63cd∕A and a low turn-on voltage of 2.89V.

The authors report excellent white organic light-emitting diodes (WOLEDs) made of 9,9bis[4-(di-p-tolyl)aminophenyl]-2,7-bis(diphenylamino)fluorene (TADPF) or 9,9-bis[4-(di-p-tolyl)aminophenyl]-2,7-bis(9-carbazolyl)fluorene (TAKF). The superposition of a yellow emission coming from the TADPF or TAKF electromer and a blue emission originating from bis(2-(2-hydroxyphenyl)benzothiazolate)zinc gives rise to a pure white-light emission. The multilayer device using TADPF shows a maximum luminance of 5123cd∕m2, a current efficiency of 2.8cd∕A, and Commission Internationale d’Eclairage chromaticity coordinates of (0.33, 0.33). This result is the optimal for WOLEDs based on electromers so far reported.

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 2.6V and the maximum efficiency of 5.1cd∕A are achieved.

Employing 5,5′-bis-biphenyl-dithieno[3,2-b:2′,3′-d]thiophene (BPDTT) as semiconducting layer and poly(vinyl alcohol) (PVA) as gate dielectric layer, we have fabricated organic thin-film transistors. These devices exhibit excellent field-effect performances with a high mobility of up to 0.6cm2∕Vs and a very low operating voltage (

We fabricate single-walled carbon nanotube field-effect transistors (SWNT FETs) with a simple, low-cost, high-efficiency, and solution-based orientational self-assembly method. The SWNT was first functionalized with thiol groups, then suspended in an N,N-dimethylformamide solution, and finally self-assembled on predefined gold contact pads by an orientational N2 blow. A relatively high mobility of 9.2×102cm2∕Vs and an on∕off ratio greater than 105 at a bias voltage of −1V have been achieved as a result of directly covalent interaction between end-thiolated SWNT and gold contacts, which favors the fabrication of SWNT FETs as compared to the SWNT FETs bearing the similar geometry but relies on random deposition. Therefore, this orientational self-assembly approach should be a valuable tool in the mass fabrication of high-performance SWNT FETs and SWNT-based molecular-scale electronic devices.

We report an efficient blue light-emitting diode (LED) using N, N′-bis(1-naphthyl)-N, N′-diphenylbenzidine as an emitting layer and tetra(β-naphthyl)silane (TNS) as a hole-blocking layer (HBL). We find that the hole-blocking performance, thermal stability, and film-forming ability of TNS are improved over those of the prototypical hole-blocking material 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP). The device that used TNS as the HBL exhibits a narrower light emission and higher current efficiency (2.5cd∕A) as compared with the device containing BCP as the HBL. TNS should be promising as an excellent hole-blocking layer in LEDs.

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.