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In this paper, four new π-conjugated dendrimers G1and G2-1–G2-3, constructed by triphenylamine and carbazole moieties, have been successfully prepared viaa simple synthetic route. This molecular design imparts the materials with good solution-processability, high thermal and morphological stabilities, and low oxidation potential, all of which are promising properties for optoelectronic materials. The double-layer OLEDs fabricated using these materials through solution processing demonstrate that they can exhibit dual functions, hole-transporting and light-emitting. Devices using G1or G2-1as the hole-transporting layer present good stability during the passage of current, with a maximum efficiency of 1.70 and 1.59 cd A−1, respectively. Moreover, devices using these dendrimers as the emitting layer show moderate performance, and the device of G2-2gives a maximum luminance and efficiency of 1190 cd m−2and 1.67 cd A−1, respectively, thanks to three-dimensional building of the dendritic system, which might suppress the inherent reductive or aggregation-caused quenching that usually happens for triphenylamine/carbazole derivatives to some degree. Also, the photo-cross-linking property of triple bonds enables ready fabrication of highly fluorescent photoresist patterns of these dendrimers. [ABSTRACT FROM AUTHOR]

Recently, a lot of effort has been focused on improving the performance and exploring the electric properties of graphene. This article presents a summary of chemical doping of graphene aimed at tuning the electronic properties of graphene. p-Type and n-type doping of graphene achieved through surface transfer doping or substitutional doping and their applications based on doping are reviewed. Chemical doping for band gap tuning in graphene is also presented. It will be beneficial to designing high performance electronic devices based on chemically doped graphene. [ABSTRACT FROM AUTHOR]

As a new member of the carbon family, graphene has many fascinating properties and potential applications with the greatest degree of similarity to its “brother” carbon nanotubes (CNTs). Research on graphene has developed rapidly in the past 6 years, partially due to its similarity to carbon nanotubes which have been extensively studied for almost two decades. The adaptation of carbon nanotube research strategies for the development of graphene preparation, functionalization and applications as well as the conversion and hybrid structures of carbon nanotubes and graphene are reviewed in this feature article. [ABSTRACT FROM AUTHOR]

In this work, two “H”-shape and one “AB”-type second order nonlinear optical (NLO) polymers were prepared for the first time. The linkage positions of chromophores in the “H”-shape polymers were shoulder-to-shoulder, in which the chromophore moieties were part of the polymeric backbone. The subtle structure could be easily modified by the introduction of different isolation groups, to adjust the property of the resultant polymers. All the polymers exhibited good film-forming ability and thermal stability. The second harmonic generation (SHG) experiments demonstrated that the two “H”-shape polymers (P1and P2) exhibited large SHG coefficients of d33values (up to 90 pm V−1), and P2even demonstrated relatively good long-term temporal stability. [ABSTRACT FROM AUTHOR]

A series of semiconducting copolymers incorporating dithieno[3,2-b:2′,3′-d]thiophene moieties in the polythiophene backbone were synthesized. The resulting four copolymers are found to have large band gap (∼ 2.5 eV) and large ionization potential (−5.1 eV). Organic field-effect transistors were fabricated by spin-coating polymer solutions onto OTS-modified SiO2/Si substrates with top-contact configuration. The best resulting hole mobility afforded was 0.028 cm2 V−1 s−1 with an on/off ratio of 2 × 104 and a threshold voltage of about −18.9 V in the saturation regime. Furthermore, all the devices exhibited high environmental stability against oxygen doping and relatively high ambient humidity (∼30%). [ABSTRACT FROM AUTHOR]

Abnormal photoluminescent properties of polyphenylphenyl compounds 6,7-dicyano-2,3-di-[4-(2,3,4,5-tetraphenylphenyl)phenyl]quinoxaline (CPQ) and 6,7-dimethyl-2,3-di-(4-(2,3,4,5-tetraphenylphenyl)phenyl)quinoxaline (MPQ) in aqueous solutions have been investigated. Photoluminescent emissions of CPQ and MPQ in tetrahydrofuran (THF)–water mixtures do not change monotonously with increasing their effective concentration in solution. This phenomenon is different from both aggregation-induced emission quenching and aggregation-induced emission enhancement, and can be ascribed to the results of combinational effects of intramolecular rotation, intermolecular hydrogen bonds, and solvent viscosity and hydration. We also observed that organic nanoparticles of CPQ and MPQ are formed in the aqueous solutions. Based on detection of the fluorescence of CPQ nanoparticles in aqueous solutions when introducing nucleobases, we report for the first time the application of organic nanoparticles for nucleobase sensing and found that CPQ nanoparticles can recognize the nucleobases with a sensitivity of guanine > adenine > thymine ≥ cytosine. These findings elucidate the photoluminescent behavior of polyphenylphenyl compounds in aqueous solutions and provide an approach to apply fluorescent organic nanoparticles for biosensing instead of metal and inorganic nanoparticles. [ABSTRACT FROM AUTHOR]

We report high performance organic field-effect transistors (OFETs) with the modified Cu bottom-contact electrodes. Efficient modification of the Cu electrodes with nanometer-size copper tetracyanoquinodimethane (Cu-TCNQ) increases the electrode/organic layer contact area and reduces contact resistance. We investigated the effect of the Cu-TCNQ morphology on the device performance. The pentacene-based OFETs with the modified Cu bottom-contact electrodes exhibited high device performance. The field-effect mobility up to 0.31 cm2/V s was achieved. To the best of our knowledge, this is the highest device performance for the OFETs with the bottom Cu electrodes ever reported. Consequently, our results provide an effective approach to fabricate high performance and low-cost OFETs. [ABSTRACT FROM AUTHOR]

We report a novel electroluminescent material, 6,7-dicyano-2,3-di-[4-(2,3,4,5-tetraphenylphenyl)phenyl]quinoxaline (CPQ), which can be used as a multifunctional material in organic light-emitting diodes (OLEDs), serving as an effective emitting, electron-transporting, and color-tuning layer. OLEDs employing CPQ as both the emissive and electron transporting layer give bright bluish-green light emission and show a high luminous efficiency of 4.7 cd A–1. In addition, multicolor OLEDs based on CPQ and various hole transport materials (HTMs) were fabricated. We successfully achieved an effective color tuning of emission, from bluish-green through yellowish-green and yellow to reddish-orange, in OLEDs by varying HTMs. Our results provide a simple and effective approach to construction of highly efficient and multicolored OLEDs. [ABSTRACT FROM AUTHOR]

Two novel macrocycles based on triphenylamine (TPA) have been synthesized by McMurry coupling reactions. The cyclic compound 2 consisted of two triphenylamines linked with ethylene bridges bearing two n-butyl chains. The compound 3 was based on N,N,N′,N′-tetraphenylbenzidine (TPD) units with macrocyclic architecture. They were fully characterized by cyclic voltammetry, UV-vis absorption and self-assembly properties. The crystal structure of 2 was determined by X-ray analysis. Atomic force microscope and scanning electron microscope images showed that compound 3 could form interesting fiber-like nanostructures by self-assembly. Both of the compounds can be used as active layers for p-type OFETs. The OFET device based on 2 prepared via a vacuum-deposit method gave a mobility of 2.3 × 10−3 cm2 V−1 s−1 and a current on/off ratio of 105. High quality thin films of 3 were fabricated by spin coating from solution, and gave a mobility of 2.0 × 10−3 cm2 V−1 s−1 with a current on/off ratio of 2 × 105. The results showed that the TPA derivatives with cyclic structures might fit better for OFETs. They may provide promising new choices for organic semiconductors. [ABSTRACT FROM AUTHOR]

A new series of oxadiazole derivatives TPO, PPO, MTPO, MPPO, BTPO, and BPPO have been designed and synthesized in high yields by a convenient synthetic procedure. A single crystal structure of TPO exhibited that this polyphenylene-dendronized material has a sterically crowded structure which efficiently prevents π–π stacking and endows it with good thermal stability. The photophysical properties of the materials show strong emission between 376 and 390 nm in the films. In addition, good reversible reductive waves in the cyclic voltammograms implied that these materials might have good electron transport properties. Blue electrophosphorescent devices fabricated using these materials as the host materials and iridium(iii)bis[4,6-di-fluorophenyl-pyridinato-N,C2′]picolinate as the blue phosphorescent dopant emitter show very high efficiencies. A maximum luminance of 4484 cd m−2 and an external quantum efficiency of 6.20% were achieved under ambient conditions. [ABSTRACT FROM AUTHOR]

Three new linear benzene-fused bis(tetrathiafulvalene) compounds (4–6) were synthesized and characterized. Compounds 4 and 5, comprising branched alkyl chains (2-ethylbutyl and 2-ethylhexyl, respectively), had very good solubility in common organic solvents and were successfully used as p-channel semiconductors in solution-processed organic field-effect transistors (FET). The FET device based on 5 showed a mobility of 5.6 × 10−4 cm2 V−1 s−1 with an on/off ratio of 1.6 × 104, and the devices based on 4 and 5 displayed good reproducibility in air. In addition, 6, bearing the long n-dodecyl chains, exhibited self-assembly behavior; one-dimensional self-assembly micron-scale ribbons formed in solution and were revealed by scanning electron microscopy on SiO2 substrates. [ABSTRACT FROM AUTHOR]

A fused-seven-ring anthracene derivative with two sulfur bridges, benzobisthioxanthene (BTA), was synthesized, facilely. OLEDs employing BTA as the emitter exhibited bright (maximum 40 752 cd m-2) and efficient red emission (CIE, x = 0.64, y = 0.36) with a luminous efficiency of 4.4 cd A-1. [ABSTRACT FROM AUTHOR]

A new rigid cyclic thiophene molecule was synthesized and its unusual and interesting single-crystal tubular products on a millimeter scale were obtained unexpectedly by a simple self-assemble technique in a solution process under ambient conditions. [ABSTRACT FROM AUTHOR]

A novel type of antiand synisomers of a pentacyclic compound consisting of two thiophene rings and one pyrrole ring were efficiently synthesized from benzo[b]thiophene, and the antiisomer exhibits better charge transport and OFET properties compared with the synisomer and its N-hexyl substitution. [ABSTRACT FROM AUTHOR]

Bulky 4-tritylphenylethynyl substituted boradiazaindacene with pure red emission, relatively large Stokes shift, high fluorescence quantum yield, and low self-quenching was efficiently synthesized and qualified as a potential EL dopant. [ABSTRACT FROM AUTHOR]

Photoluminescence of simple arylbenzenes with ready synthetic accessibility is enhanced by two orders of magnitude through aggregate formation; viscosity and temperature effects indicate that the emission enhancement is due to the restriction of their intramolecular rotations in the solid state. [ABSTRACT FROM AUTHOR]