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Treatment of myocardial infarction (MI) remains a major challenge. The chemokine family plays an important role in cardiac injury, repair, and remodeling following MI, while stromal cell-derived factor-1 alpha (SDF-1α) is the most promising therapeutic target. This study aimed to increase SDF-1α expression using a novel gene delivery system and further explore its effect on MI treatment. In this study, two kinds of plasmids, human SDF-1α plasmid (phSDF-1α) and human SDF-1α- nuclear factor κB plasmid (phSDF-1α-NFκB), were constructed and loaded onto cationic microbubble carriers, and the plasmids were released into MI rabbits by ultrasound-targeted microbubble destruction. The transfection efficiency of SDF-1α and the degree of heart repair were further explored and compared. In the MI rabbit models, transfection with phSDF-1α-NFκB resulted in higher SDF-1α expression in peri-infarct area compared with transfection with phSDF-1α or no transfection. Upregulation of SDF-1α was shown beneficial to these MI rabbit models, as demonstrated with better recovery of cardiac function, greater perfusion of the myocardium, more neovascularization, smaller infarction size and thicker infarct wall 1 month after treatment. Ultrasound-targeted cationic microbubbles combined with the NFκB binding motif could increase SDF-1α gene transfection, which would play a protective role after MI.

Developing new materials for the fabrication of resistive random-access memory is of great significance in this period of big data. Herein, we present a novel design strategy of embedding donor (D) and acceptor (A) fragments into imine-linked frameworks to construct resistive switching covalent organic frameworks (COFs) for high-performance memristors. Two D-A-type two-dimensional COFs, COF-BT-TT and COF-TT-TVT, were designed and synthesized using a conventional solvothermal approach, and high-quality thin films of these materials deposited on ITO substrate exhibited great potential as an active layer for memristors. Rewritable memristors based on 100 nm thick COF-TT-BT and COF-TT-TVT films showed a high ON/OFF current ratio (ca. 105 and 104 ) and low driving voltage (1.30 and 1.60 V). The cycle period and retention time for COF-TT-BT-based rewritable devices were as high as 319 cycles and 3.3×104 s at a constant voltage of 0.1 V (160 cycles and 1.2×104 s for the COF-TT-TVT memristor).

Multiple-resonance (MR) organic emitters bearing small full-width at half-maximums (FWHMs) are of general interest in organic light-emitting diodes. Indolo[3,2,1- jk ]carbazole (ICz) embedded MR-fluorophors have demonstrated extremely small FWHMs, yet in the violet region with low electroluminescence efficiency. Herein, a strategic implementation of ICz subunits into MR fluorophors is proposed by taking advantage of the synergetic effect of para -positioned nitrogen atoms to enhance electronic coupling to decrease emitting energy gap. Deep blue emitters peaking at 441 and 447 nm with FWHMs of only 18 and 21 nm are thereof obtained respectively, accompanied by ~90% photo-luminance quantum yields. With the assistance of a thermally activated delayed fluorescence sensitizer to recycle excitons, the corresponding narrowband electroluminescent devices show unprecedent high maximum external quantum efficiencies of 32.0% and 34.7% with CIE y of 0.10 and 0.085, respectively.

Graphene‐based moiré heterostructures are strongly correlated materials, and they are considered to be an effective platform to investigate the challenges of condensed matter physics. This is due to the distinct electronic properties that are unique to moiré superlattices and peculiar band structures. The increasing research on strongly correlated physics via graphene‐based moiré heterostructures, especially unconventional superconductors, greatly promotes the development of condensed matter physics. Herein, the preparation methods of graphene‐based moiré heterostructures on both in situ growth and assembling monolayer 2D materials are discussed. Methods to improve the quality of graphene and optimize the transfer process are presented to mitigate the limitations of low‐quality graphene and damage caused by the transfer process during the fabrication of graphene‐based moiré heterostructures. Then, the topological properties in various graphene‐based moiré heterostructures are reviewed. Furthermore, recent advances regarding the factors that influence physical performances via a changing twist angle, the exertion of strain, and regulation of the dielectric environment are presented. Moreover, various unique physical properties in graphene‐based moiré heterostructures are demonstrated. Finally, the challenges faced during the preparation and characterization of graphene‐based moiré heterostructures are discussed. An outlook for the further development of moiré heterostructures is also presented., This review presents the preparation and optimization of graphene‐based moiré heterostructures, including twisted bilayer graphene, twisted trilayer graphene, twisted double bilayer graphene, graphene/ hexagonal boron nitride, and graphene/transition metal dichalcogenides. The topological properties and correlated physical performances are comprehensively illustrated. A clear understanding of the mechanism regarding many‐body physics will be a breakthrough for condensed matter physics.

Multifunctional materials that exhibit different physical properties in a single phase have potential for use in multifunctional devices. Herein, we reported an organic-inorganic hybrid compound [(18-crown-6)K][Fe(1)Cl(1)4 ]0.5 [Fe(2)Cl(2)4 ]0.5 (1) by incorporating KCl and FeCl3 into a 18-crown-6 molecule, which acts as a host of the six O atoms providing a lone pair of electrons to anchor the guest potassium cation, and [FeCl4 ]- as a counterion for charge balance to construct a complex salt. This salt exhibited a one-step reversible structural transformation giving two separate high and low temperature phases at 373 K, which was confirmed by systematic characterizations including differential scanning calorimetry (DSC) measurements, variable-temperature structural analyses, and dielectric, impedance, variable-temperature magnetic susceptibility measurements. Interestingly, the structural transformation was coupled to both hysteretic dielectric phase transition, conductivity switch and magnetic-phase transition at 373 K. This result gives an idea for designing a new type of phase-transition materials harboring technologically important magnetic, conductivity and dielectric properties.

To achieve sustainable production of hydrogen (H2) through water splitting, establishing efficient and earth-abundant electrocatalysts is of great necessity. Here, we firstly reveal that morphology engineering of graphene can modulate the electronic structure of carbon skeleton and in turn endow it with excellent ability of proton reduction. Three-dimensional (3D) graphene networks with the high density of sharp edge sites are synthesized. Electrocatalytic measurements indicate that the obtained 3D graphene networks can electrocatalyze H2 evolution with an extremely low onset potential of ~18 mV in 0.5 M H2SO4 solution, together with good stability. A combination of control experiments and density functional theory (DFT) investigations indicates that the exceptional H2 evolution performance is attributed to the abundant sharp-edge sites of the advanced frameworks, which are responsible for promoting the adsorption and reduction of protons.

A new conjugated polymer (PBAIIDTT) based on bay-annulated indigo and indacenodithieno[3,2-b]thiophene was designed, synthesized, and characterized. PBAIIDTT shows strong absorption in 400–500 and 600–800 nm, and its HOMO and LUMO energy levels are −5.45 eV and −3.65 eV, respectively. In organic field-effect transistors, the polymer exhibits a relatively high hole mobility of 0.39 cm2 V−1 s−1. PBAIIDTT was added to poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PC61BM) based organic solar cells. Ternary blend solar cells with 10% PBAIIDTT show an increased short circuit current density due to the broadened photocurrent generated in the near-infrared region, and a power conversion efficiency of 3.78%, which is higher than that of the P3HT:PC61BM binary control devices (3.33%). © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

In this work, we report the synthesis, characterization, and application of two regioirregular naphthalenediimide (NDI)-based alternating conjugated polymers, namely P1 and P2, in which nitrile-substituted moiety, 2,3-bis(thiophen-2-yl)acrylonitrile and NDI moiety act as donor and acceptor unit, respectively. The two regioirregular polymers possess low-lying LUMO energy levels of −3.92 eV for P1 and −3.96 eV for P2. Both polymers possess typical dual-band UV−Vis−NIR absorption profiles of NDI-based polymers, and show broadened and red-shifted absorption spectra in the solid state compared with those in solutions. Field-effect transistor devices with top-gate bottom-contact configuration were used to evaluate the polymers' semiconducting properties. The two polymers exhibited promising and air-stable ambipolar charge transport characteristics. Thin film microstructure investigations (AFM and 2D-GIXRD) suggest both polymers formed continuous and smooth thin films, and adopted predominantly face-on molecular packing in the solid state. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

Constructing planar, rigid, and high electronically delocalized π-conjugated molecular system is the most basic requirements of obtaining high-performance polymeric semiconductors for organic field-effect transistors (OFETs). In this regard, diarylethylene (DAE)-based polymers show great potential because many substantive progresses related to polymer field-effect transistors had been achieved from the kind of polymer materials in recent years. In the brief review, series of DAE-based polymer are highlighted, based on which several design strategies have been summarized by the way of comparative research method. These strategies have important guiding significance not only for further developing new DAE-based and other polymeric semiconductors for OFETs but also for developing specific polymeric semiconductors for other organic electronics, such as organic photovoltaics and organic light-emitting diodes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 585–603

Graphene is the most broadly discussed and studied two-dimensional material because of its preeminent physical, mechanical, optical, and thermal properties. Until now, metal-catalyzed chemical vapor deposition (CVD) has been widely employed for the scalable production of high-quality graphene. However, in order to incorporate the graphene into electronic devices, a transfer process from metal substrates to targeted substrates is inevitable. This process usually results in contamination, wrinkling, and breakage of graphene samples - undesirable in graphene-based technology and not compatible with industrial production. Therefore, direct graphene growth on desired semiconductor and dielectric substrates is considered as an effective alternative. Over the past years, there have been intensive investigations to realize direct graphene growth using CVD methods without the catalytic role of metals. Owing to the low catalytic activity of non-metal substrates for carbon precursor decomposition and graphene growth, several strategies have been designed to facilitate and engineer graphene fabrication on semiconductors and insulators. Here, those developed strategies for direct CVD graphene growth on semiconductors and dielectrics for transfer-free fabrication of electronic devices are reviewed. By employing these methods, various graphene-related structures can be directly prepared on desired substrates and exhibit excellent performance, providing versatile routes for varied graphene-based materials fabrication.

Long distance spin transport and photoresponse are demonstrated in a single F16 CuPc spin valve. By introducing a low-temperature strategy for controlling the morphology of the organic layer during the fabrication of a molecular spin valve, a large spin-diffusion length up to 180 nm is achieved at room temperature. Magnetoresistive and photoresponsive signals are simultaneously observed even in an air atmosphere.

1D graphene nanoribbons (GNRs) have a bright future in the fabrication of next-generation nanodevices because of their nontrivial electronic properties and tunable bandgaps. To promote the application of GNRs, preparation strategies of miscellaneous GNRs have to be developed. The GNRs prepared by top-down approaches are accompanied by uncontrolled edges and structures. In order to overcome the difficulties, bottom-up methods are widely used in the growth of various GNRs due to controllability of GNRs' features. Among those bottom-up methods, the on-surface synthesis is a promising approach to prepare GNRs with distinct widths, edge/backbone structures, and so forth. Therefore, modified engineering of the GNRs prepared via on-surface synthesis is of great significance in controllable preparation of GNRs and their potential applications. In the past decade, there have been a lot of reports on controllable preparation of GNRs using on-surface synthesis approach. Herein, the advances of GNRs grown via on-surface growth strategy are described. Several growth parameters, the latest advances in the modification of the GNR structure and width, the GNR doping/co-doping with heteroatoms, a variety of GNR heterojunctions, and the device application of GNRs are reviewed. Finally, the opportunities and challenges are discussed.

Three novel dibenzo[a, d] cyclohepten-5-one derivatives containing hole-transporting groups were synthesized and characterized. These compounds exhibit good thermal stabilities. Single crystals of DBHO-TPA and DBHO-DPA were successfully grown from dichloromethane and their crystal structures were determined from X-ray diffraction data. Two molecules, DBHO-TPA and DBHO-DPA, have a nonplanar structure while seven-membered ring comprised in dibenzo[a, d] cyclohepten-5-one is not planar. Electrochemical properties of three compounds indicate that the different substituents on 3,7-positions of the dibenzo[a, d] cyclohepten-5-one derivatives have a small effect on the energy levels of the highest occupied molecular orbitals. The blue-green light-emitting diodes based on dibenzo[a, d] cyclohepten-5-one derivatives were fabricated.

D. Geng, H. Wang, Dr. B. Luo, J. Xu, Prof. G. Yu Beijing National Laboratory for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 100190 , PR China E-mail: yugui@iccas.ac.cn D. Geng, H. Wang, J. Xu University of Chinese Academy of Sciences Beijing 10049 , PR China Y. Wan, Prof. Z. Xu Applied Mechanics Laboratory, Department of Engineering Mechanics and Center for Nano and Micro Mechanics Tsinghua University Beijing 100084 , PR China

Recently developed chemical vapor deposition (CVD) is considered as an effective way to large-area and high-quality graphene preparation due to its ultra-low cost, high controllability, and high scalability. However, CVD-grown graphene film is polycrystalline, and composed of numerous grains separated by grain boundaries, which are detrimental to graphene-based electronics. Intensive investigations have been inspired on the controlled growth of graphene single crystals with the absence of intrinsic defects. As the two most concerned parameters, the size and morphology serve critical roles in affecting properties and understanding the growth mechanism of graphene crystals. Therefore, a precise tuning of the size and morphology will be of great significance in scale-up graphene production and wide applications. Here, recent advances in the synthesis of graphene single crystals on both metals and dielectric substrates by the CVD method are discussed. The review mainly covers the size and morphology engineering of graphene single crystals. Furthermore, recent progress in the growth mechanism and device applications of graphene single crystals are presented. Finally, the opportunities and challenges are discussed.

In this article, a versatile 2-D conjugated polymer, PNDTP-DPP, containing alkylphenyl substituted naphthodithiophene is synthesized and characterized. PNDTP-DPP exhibits good solubility and crystallinity with a π-π stacking distance of ≈3.7 Å. Investigation of polymer solar cells (PSCs) and organic field-effect transistors (OFET) demonstrates a promising power conversion efficiency (PCE) of 4.11% and a high hole mobility of up to 0.86 cm(2) V(-1) s(-1) , so this is one of the few examples of versatile polymers that show both good field-effect mobility and PCE.

The controlled fabrication of single-crystal twelve-pointed graphene grains is demonstrated for the first time by ambient pressure chemical vapor deposition on a liquid Cu surface. An edge-diffusion limited mechanism is proposed. The highly controllable growth of twelve-pointed graphene grains presents an intriguing case for the fundamental study of graphene growth and should exhibit wide applications in graphene-based electronics.

In this report, four donor-acceptor copolymers, P(NDT3-BT), P(NDT3-BO), P(NDF3-BT), and P(NDF3-BO), using 5,10-didodecyl-naphtho[1,2-b:5,6-b]dithiophene (NDT3) or 5,10-didodecyl-naphtho[1,2-b:5,6-b]difuran (NDF3) as an electron-rich unit and benzodiathiazole (BT) or benzoxadiazole (BO) as an electron-deficient one, were designed, synthesized, and characterized. Detailed systematical investigation was developed for studying the effect of the S/O atoms on the optical, electrochemical, and morphological properties of the polymers, as well as the subsequent performance of the organic field-effect transistors (OFETs) fabricated from these copolymers. It was found that, compared with NDF3-based P(NDF3-BT)/P(NDF3-BO), by replacing NDF3 with stronger aromatic NDT3, the resultant P(NDT3-BT)/P(NDT3-BO) show smaller lamellar distance with an increased surface roughness in solid state, and relatively higher hole mobilities are obtained. The hole mobilities of the four polymers based on OFETs varied from 0.20 to 0.32 cm(2)V(-1)s(-1) depending on their molecular structures, giving some valuable insights for the further design and development of a new generation of semiconducting materials. (c) 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2465-2476

Two furan-flanked polymers poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-thienylenevinylene} (PDVFs), with a highly π-extended diketopyrrolopyrrole backbone, are developed for solution-processed high-performance polymer field-effect transistors (FETs). Atomic force microscopy and grazing incidence X-ray scattering analyses indicate that PDVF-8 and PDVF-10 films exhibit a similar nodular morphology with the ultrasmall lamellar distances of 16.84 and 18.98 A, respectively. When compared with the reported polymers with the same alkyl substitutes, this is the smallest d-spacing value observed to date. This closed lamellar crystallinity facilitates charge carrier transport. Therefore, polymer thin-film transistors fabricated from as-spun PDVF-8 films exhibit a high hole mobility exceeding 1.0 cm2 V−1 s−1 with a current on/off ratio above 106. After annealing treatment at 100 °C in air, the highest hole mobility of PDVF-8-based FETs was significantly improved to 1.90 cm2 V−1 s−1, which is among the highest values of the reported FET devices fabricated from polymer thin films based on this mild annealing temperature. In contrast, long alkyl-substituted PDVF-10 exhibited a relatively low hole mobility of 1.65 cm2 V−1 s−1 mainly resulting from low molecular weight. This work demonstrated that PDVFs would be promising semiconductors for developing cost-effective and large-scale production of flexible organic electronics. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1970–1977

Organic/polymeric semiconductors are mainly composed of aromatic systems including phenyl, vinyl, alkynyl, thienyl, and other isoelectric groups, which are constructed of carbon, hydrogen, and so-called 'hereroatoms' including chalcogen, nitrogen, and halogen atoms etc. The introduction of heteroatoms could yield different electronic properties by influencing the molecular geometry, the HOMO and LUMO energy levels, intermolecular interactions and so on. In this Research News article, we provide a brief review of the effect of heteroatoms and recent developments in heteroatom substituted organic/polymeric semiconductors, focusing especially on their application in field-effect transistors.

“Regioselectivity deposition” method is developed to pattern silver electrodes facilely and efficiently by solution-process with high resolution (down to 2 μm) on different substrates in A4 paper size. With the help of this method, large-area, flexible, high-performance polymer field-effect transistors based on the silver electrodes and polyimide insulator are fabricated with bottom-contact configuration by all-solution processes. The polymer devices exhibit high performance with average field-effect mobility over 1.0 cm2 V−1 s−1 (the highest mobility up to 1.5 cm2 V−1 s−1) and excellent environmental stability and flexibility, indicating the cost effectiveness of this method for practical applications in organic electronics.

Hierarchical graphene architectures (HGAs) that grow by stacking of layers are produced on a liquid copper surface using chemical vapor deposition. The stacking mode--for example hexagonal-hexagonal-hexagonal or hexagonal-snowflake-dendritic--can be simply controlled. Measurements of the electrical properties of HGAs indicate that hierarchical stacking of graphene may be a simple and effective way of tailoring their properties without degrading them.

In the field of all-polymer solar cells (all-PSCs), all efficient polymer acceptors that exhibit efficiencies beyond 8% are based on either imide or dicyanoethylene. To boost the development of this promising solar cell type, creating novel electron-deficient units to build high-performance polymer acceptors is critical. A novel electron-deficient unit containing B←N bonds, namely, BNIDT, is synthesized. Systematic investigation of BNIDT reveals desirable properties including good coplanarity, favorable single-crystal structure, narrowed bandgap and downshifted energy levels, and extended absorption profiles. By copolymerizing BNIDT with thiophene and 3,4-difluorothiophene, two novel conjugated polymers named BN-T and BN-2fT are developed, respectively. It is shown that these polymers possess wide absorption spectra covering 350-800 nm, low-lying energy levels, and ambipolar film-transistor characteristics. Using PBDB-T as the donor and BN-2fT as the acceptor, all-PSCs afford an encouraging efficiency of 8.78%, which is the highest for all-PSCs excluding the devices based on imide and dicyanoethylene-type acceptors. Considering that the structure of BNIDT is totally different from these classical units, this work opens up a new class of electron-deficient unit for constructing efficient polymer acceptors that can realize efficiencies beyond 8% for the first time.