Single-walled carbon nanotubes (SWCNTs) have attracted considerable attention owing to their applications in various fields such as biotechnology and biomedicine. Recently, aggregated SWCNTs have shown more significant effects on the treatment of methamphetamine addiction (Nat. Nanotech. 2016, 11, 613). However, the mechanisms underlying these actions are unclear. By using all-atom molecular dynamics simulations, we investigate the effects of single and aggregated SWCNTs (single-(10,10)CNT, aggregated-7-(10,10)CNTs, and single-(35,35)CNT with the same diameter as that of the aggregated one) on the activity of dopamine-related proteins [tyrosine hydroxylase (TyrOH) and dopamine transporter (DAT), which are related to the synthesis and transport of dopamine, respectively]. We find that both TyrOH and DAT can adsorb onto these SWCNTs. For TyrOH, the aggregated-7-(10,10)CNTs mainly affect the conformation of the active site of the protein, and hence, they are more effective in inhibiting the expression of TyrOH. For DAT, our results suggest that the aggregated-7-(10,10)CNTs allow DAT to maintain an outward-facing conformation and hence are favorable to the reuptake of dopamine. The binding of a dopamine reuptake inhibitor, [3H]-WIN35,428, to DAT is significantly disrupted by aggregated-7-(10,10)CNTs and hence improve the ability to transport dopamine. Our results provide the dynamic interactions of proteins with single/aggregated SWCNTs, which illustrate the mechanism of aggregated SWCNTs for the treatment of drug addiction.Keywords: conformational changes; dopamine-related proteins; interactions; MD simulations; single-walled carbon nanotubes;

This work reports a synergistic study of a noble metal (NM)/semiconductor hybrid structure featuring a mono/bimetallic PdPt/TiO2 heterostructure prepared by a facile anodization-hydrothermal process. The electronic interaction between TiO2 nanotubes (NTs) and mono/bimetallic PdPt nanoparticles (NPs), as well as the bimetallic PdPt interplay, has been thoroughly investigated by various X-ray techniques. Particularly, X-ray absorption near edge structure (XANES) at the Ti L3,2-edge and O K-edge was employed to understand the NM sensitization effect on the local structure of the TiO2 host. Meantime, d-charge redistribution within Pd and Pt upon alloying and loading on TiO2 NTs was disclosed at the Pt L3-edge and Pd L3-edge XANES, respectively. Consistent results were given from their corresponding X-ray photoemission spectroscopy (XPS) analysis. In addition, extended X-ray absorption fine structure (EXAFS) at the Pt L3-edge and Pd K-edge was also performed to unravel the atomic distribution and intermetallic interaction of Pd and Pt upon alloying. Finally, the synergy within the mono/bimetallic PdPt/TiO2 heterostructure was examined by size, compostion, and structure of the as-attached NM NPs assisted with photoresponse performance analysis.

•Heterojunction can improve operating stability of pentacene-based OTFT.•The heterojunction-induced surface doping is nondestructive and can be controlled.•Current flow in pentacene bulk is more stable than that in bottom conducting channel.•Carrier trapping associated with gate dielectric is faster than that in active layer.The introduction of an inorganic/organic or organic/organic heterojunction in the pentacene-based organic field-effect transistors is demonstrated to be in favor of improving their operating stability. The heterojunction-induced p-type doping of pentacene is nondestructive, and it can be controlled by varying the adlayer thickness. The bias stress effects are compared at similar surface carrier density for the doped and undoped devices, and the current flow in the pentacene bulk is found to be more stable than that in the conducting channel close to the gate dielectric. In the initial stage of the bias stress characteristics, the carrier trapping associated with the gate dielectric is mainly responsible for the current instability. On the other hand, in the prolonged stage, the carrier trapping in the active layer may become dominant.

Ultraviolet (UV) monitoring has wide applications in diverse fields, where sensitive photodetection and recording of UV exposure history are often simultaneously required. A new strategy is herein developed to achieve solar-blind UV monitoring. Based on organic field-effect transistors (OFETs), nonvolatile memories with both p-type or n-type organic active layers demonstrate selective and storable UV response. These OFET memories are sensitive only to solar-blind UV light of 254 nm, and have no response to UV light of 365 nm or visible light. The photoresponsive signal can be recorded in a nonvolatile manner with excellent retention and rewritable capability, which integrates solar-blind UV detection and memory into a single device. These OFET memories are well compatible with flexible substrates, and thus could be very useful for portable and/or wearable UV dosimetry. The conventional bandgap photoexcitation mechanism is not applicable to the this case, and a UV-induced interfacial excitation mechanism is proposed to interpret the device features.

Fully integrated ultrathin, transparent and foldable energy storage devices are essential for the development of smart wearable electronics, yet typical supercapacitor electrodes are substrate-supported which limits their thickness, transparency and mechanical properties. Employing freestanding transparent electrodes with no substrate support could bring ultrathin, foldable and designable supercapacitors closer to reality. Herein, we report a freestanding, ultrathin (<5 μm), highly conductive (3 × 104 S cm−1), highly transparent (>84% transmittance) and foldable metallic network electrode, loaded with MnO2 by electrochemical deposition, as a supercapacitor electrode. The freestanding metallic network electrode is fabricated via a simple and low-cost laser direct-writing micro-patterning technique followed by a selective electrodeposition process, where the metallic network patterns, network periods, metal thickness and also the electrode film patterns can be designed for different applications. The obtained freestanding MnO2@Ni network electrode delivers an outstanding areal capacitance of 80.7 mF cm−2 and long-term performance stability (96.3% after 10 000 cycles). Moreover, the symmetric solid-state supercapacitors employing the freestanding MnO2@Ni network electrode not only show high areal capacitance as well as high optical transparency (>80% transmittance), but also can be tailored, attached, folded, rolled up, and crumpled into any object or various shapes with only slight performance degradation. The advent of such freestanding transparent metallic network electrodes may open up a new avenue for realizing fully integrated ultrathin, foldable and designable supercapacitors towards self-powered wearable electronics.

We present a straightforward physical approach for synthesizing multiwalled carbon nanotubes (CNTs)-PdAu/Pt trimetallic nanoparticles (NPs), which allows predesign and control of the metal compositional ratio by simply adjusting the sputtering targets and conditions. The small-sized CNTs-PdAu/Pt NPs (~3 nm, Pd/Au/Pt ratio of 3:1:2) act as nanocatalysts for the methanol oxidation reaction (MOR), showing excellent performance with electrocatalytic peak current of 4.4 A mgPt−1 and high stability over 7000 s. The electrocatalytic activity and stability of the PdAu/Pt trimetallic NPs are much superior to those of the corresponding Pd/Pt and Au/Pt bimetallic NPs, as well as a commercial Pt/C catalyst. Systematic investigation of the microscopic, crystalline, and electronic structure of the PdAu/Pt NPs reveals alloying and charge redistribution in the PdAu/Pt NPs, which are responsible for the promotion of the electrocatalytic performance.

A novel approach to fabricate large-scale embedded metallic mesh transparent conductive electrodes (TCEs) on flexible substrates via a low-cost and facile selective electrodeposition process combined with inverted film-processing methods is proposed for the first time. The optimized embedded Ni mesh TCEs on polyethylene terephthalate (PET) exhibit excellent optoelectronic properties (Rs ∼ 0.2 Ω sq−1 & T ∼ 84%), high figure of merit (FOM ∼ 1.0 × 104) and mechanical durability properties, which arise from the embedded inverted T-type shape of the electrodeposited Ni mesh. The resultant embedded Ni mesh/polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid electrodes are utilized both as current collectors and active electrode materials for all-solid-state flexible transparent supercapacitors, which show high transparency, superior electrochemical performances, excellent mechanical flexibility and high capacitance retention. Even after 1000 cycles of repetitive bending with a radius of 2 mm, the capacitance exhibited a decrease within only 5.2%. The high performance can be attributed to the excellent optoelectronic properties of embedded Ni mesh electrodes in combination with superior electrochemical properties of PEDOT:PSS. This provides a simple, cheap and controllable method for fabricating high-performance flexible TCEs and thus constructing flexible and transparent energy conversion and storage devices and systems.

•A low-cost and low-temperature solution process is developed to prepare excellent Al2O3 gate dielectric.•Both p-type and n-type high-performance low-voltage organic field-effect transistors are realized utilizing Al2O3 dielectric.•High quality of Al2O3 dielectric results in high operating stability of organic field-effect transistors.•A flexible low-power complementary inverter with a large gain is achieved utilizing Al2O3 dielectric.Organic-based complementary inverter could be a key component in future flexible and portable electronic products, which require low-power operation, high operating stability and flexible compatibility at the same time. A simple method for making excellent Al2O3 gate dielectric is developed toward the target, and it is a low-cost solution process with a low annealing temperature compatible with plastic substrates. Utilizing the Al2O3 dielectric, both p-type and n-type low-voltage organic field-effect transistors (OFETs) are realized. The device operating voltage is down to ±3 V, and the On/Off ratio is up to 106. The hole and electron field-effect mobilities are 2.7 cm2/V and 0.2 cm2/V, respectively, and the subthreshold swing is as small as about 110 mV/decade. The high quality of the Al2O3 dielectric results in high operating stability of the devices. The p-type and n-type OFETs are integrated to achieve a low-power complementary inverter with a large gain, which can be successfully fabricated on a flexible substrate.

•Small-sized Al nanoparticles on ITO can act as electron injection hotspots in inverted OLEDs.•Injection hotspots can reduce voltage and improve efficiency for both fluorescent and phosphorescent OLEDs.•Injection hotspots have minor effects on surface roughness, transparency and work function of ITO.•The hotspot effect arises from efficient electron injection due to enhanced local electric field.Al nanoparticles, with small size and ultralow coverage on ITO, can play a key role as the electron injection hotspots in both the inverted fluorescent and phosphorescent organic light-emitting diodes. The presence of the hotspots greatly reduces the operational voltage and improves the current efficiency of the devices, which are strongly dependent on the hotspot size. The microscopic and spectroscopic characterization demonstrate that the small-sized hotspots have a minor influence on the surface roughness, transparency and work function of ITO. The hotspot effect is ascribed to the highly efficient electron injection at the Al nanoparticles enhanced by the local electric field, and a physical model is proposed to clarify this mechanism. The finding indicates a promising strategy by design and craft of the injection hotspots in nanoscale to facilitate carrier injection in organic thin film devices.

•AuPd alloy NPs supported on graphene were synthesized via one-step sputtering deposition.•Highest activity of AuPd(1:3) NPs for ethanol electro-oxidation in alkaline media was confirmed.•Synergistic effect between Au and Pd promotes the anti-poisoning performance.•AuPd(1:3) alloy NPs show extraordinarily durability after 500 cyclic voltammograms.Room-temperature-ionic-liquid-assisted sputtering with an alloy target is utilized to synthesize the graphene-supported AuPd alloy nanoparticles, whose Au-to-Pd ratio can be well controlled. The preparation process is one-step, free of additives and stabilizers. For direct electro-oxidation of ethanol in alkaline media, the supported AuPd alloy nanoparticles show much higher catalytic activity compared with a commercial Pd/C catalyst and the monometallic counterpart. The optimal Au-to-Pd ratio is 1:3, and the nanocatalyst of AuPd (1:3) possesses high stability and durability. After 500 cyclic voltammetry test cycles, the anodic peak current density for ethanol electro-oxidation still remains about 91% of the initial one. Furthermore, by quantitatively analyzing the relative reactivity retention, the alloy nanoparticle catalysts with graphene as the support show much higher anti-poisoning performance than the corresponding monometallic catalysts with active C as the support.

A simple one-pot method was developed to prepare PtNi alloy nanoparticles, which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid. The nanohybrids are targeting stable nanocatalysts for fuel cell applications. The sizes of the supported PtNi nanoparticles are uniform and as small as 1–2 nm. Pt-to-Ni ratio was controllable by simply selecting a PtNi alloy target. The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation. The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst. The electronic structure characterization on the PtNi nanoparticles demonstrates that the electrons are transferred from Ni to Pt, which can suppress the CO poisoning effect.

Graphene-supported bimetallic nanoparticles are promising nanocatalysts, which can show strong and tunable catalytic activity and selectivity. Herein room-temperature-ionic-liquid-assisted metal sputtering is utilized to synthesize PdAu bimetallic nanoparticles on graphene with bare surface, small size, high surface density and controlled Pd-to-Au ratio. This controllable synthetic approach is green-chemistry compatible and totally free of additives and byproducts. The supported PdAu nanoparticles show excellent catalytic capabilities for both oxidation and reduction reactions, strongly dependent on the Pd-to-Au ratio. A strong correlation among catalytic performance, bimetallic composition and charge redistribution in the PdAu nanoparticles has been demonstrated. The results suggest that sufficient Au d-holes appear to be significant to the catalysis of oxidation reaction, and a metallic Pd surface is critical to the catalysis of reduction reaction. By the present method, the bimetallic combination can be tailored for distinct types of catalytic reactions.

•Novel blue fluorescent emitters based on twisted anthracene derivatives were synthesized.•The efficiency of p-PABPI is three times of m-PABPI for the non-doped electroluminescent devices.•The performance of blue OLEDs can be significantly improved by tunable molecular configuration.Two novel twisted anthracene derivatives, 2-(4-(10-(phenanthren-9-yl)anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro[9,10-d]-imidazole (p-PABPI) and 2-(3-(10-(phenan-thren-9-yl)anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro-[9,10-d]imidazole (m-PABPI), have been synthesized. Their photophysical and photochemical properties are also investigated systemically. The non-doped fluorescent organic light-emitting diodes are fabricated by using anthracene derivatives as the emitters. The maximum current efficiencies are achieved to be 3.98 and 1.32 cd A−1 and the maximum power efficiencies are 2.80 and 1.14 lm W−1, respectively. The external quantum efficiency maximum (EQEmax) is 3.61% and 1.33% for p-PABPI and m-PABPI. Intriguingly, the efficiencies of p-PABPI are almost three times larger than that of m-PABPI with only the different molecular configuration. The results revealed a new rule of molecular design based on anthracene derivatives for obtaining high performance blue emission materials.

•High-performance OFET memory based on a bimetal nano-floating-gate is demonstrated.•Bimetal nano-floating-gate is achieved by solution-processed blending of stabilized Ag and Pt nanoparticles.•Bimetal device shows synergistic superiority in memory performance compared with corresponding monometal devices.•The synergistic effect is interpreted by dipole enhancement induced nanoparticle work function change.A solution-processed bimetal nano-floating-gate, with a combination of stabilized Ag and Pt nanoparticles, is utilized to achieve high-performance organic field-effect transistor nonvolatile memories. The device based on the Ag–Pt nano-floating-gate shows the synergistic superiority in memory performance compared with the corresponding Ag-only and Pt-only devices. The Ag and Pt nanoparticles are found to prefer hole and electron trapping, respectively. Upon the blending of the Ag and Pt nanoparticles, both hole and electron trapping are significantly enhanced and thus realize a large memory window. The dipole enhancement induced local work function change for both Ag and Pt is proposed to be responsible for the synergistic effect, and this physical picture is supported by the electronic structure results. It is concluded that using a hybrid nano-floating-gate is a promising strategy to optimize the device performance of organic field-effect transistor nonvolatile memories.

TiO2-supported PdAu bimetallic nanoparticles (NPs) with small size and good dispersity were prepared by the room-temperature ionic liquid-assisted bimetal sputtering, which is simple, environmentally friendly, and free of additives and byproducts. Pd/Au atomic ratio can be tuned by controlling the sputtering conditions simply. High catalytic activity was found in PdAu–NPs–TiO2 hybrids for solvent-free selective oxidation of 1-phenylethanol using O2 as the oxidant at the low temperature of 50 °C and low pressure of 1 atm. It was found that Pd/Au ratio strongly affected the catalytical activity, and the highest conversion of about 35 % and turnover frequency of about 421 h−1 were achieved at 1:1 of Pd/Au atomic ratio. The synergistic effect in PdAu NPs was also discussed based on the comprehensive characterization results. The present approach may offer an alternative platform for future development of green-chemistry compatible bimetallic nanocatalysts.

Inverted organic light-emitting diodes (IOLEDs) can effectively improve device stability because they concentrate the air-stable anode and high work function (WF) metal oxide hole-injection layer (HIL) at the top of the devices. In this work, we report a facile solution-processed ultra-thin alumina film used as an electron-injection layer in IOLEDs and present significantly improved device performance. We achieved a high current efficiency of 5.12 cd A−1 at 10 mA cm−2 and the best current efficiency approaching 5.5 cd A−1 at 40 mA cm−2 without doping of an emission layer (EML) for a single Alq3-based green fluorescent IOLED, and a high current efficiency for a green phosphorescent IOLED as well. Furthermore, the extrapolated 50% decay lifetime (t50) shows that our Alq3-based green fluorescent IOLED is about 5 times more stable than the conventional OLED.

Micrometer-sized single-crystalline In2Se3 nanosheets are synthesized by epitaxial growth from In2Se3 nanowires. The In2Se3 nanosheets possess anisotropic structural configuration with intralayer covalent bonding and interlayer van der Waals bonding. Phototransistors based on the In2Se3 nanosheets are realized, and the devices show high photoresponsivity and high photo On/Off ratio up to two orders. The photo-gating effect can be modulated by the gate bias, indicating potential utility of the In2Se3 nanosheets in a variety of optoelectronic applications.

We have investigated model systems of silver clusters with different sizes (3 and 15 atoms) deposited on alumina and titania supports using ambient pressure X-ray photoelectron spectroscopy. The electronic structures of silver clusters and support materials are studied upon exposure to various atmospheres (ultrahigh vacuum, O2 and CO) at different temperatures. Compared to bulk silver, the binding energies of silver clusters are about 0.55 eV higher on TiO2 and 0.95 eV higher on Al2O3 due to the final state effect and the interaction with supports. No clear size effect of the silver XPS peak is observed on different silver clusters among these samples. Silver clusters on titania show better stability against sintering. Al 2p and Ti 2p core level peak positions of the alumina and titania support surfaces change upon exposure to oxygen while the Ag 3d core level position remains unchanged. We discuss the origin of these core level shifts and their implications for catalytic properties of Ag clusters.

•Novel blue fluorescent emitters based on spirofluorene derivatives were synthesized and characterized.•The nondoped electroluminescent devices based on them show high efficiency and blue emissions.•The results are demonstrated to be tunable electroluminescence from sky-blue to deep-blue emission.Two novel benzimidazole-attached spiro[benzofluorene] derivatives, 2,2′-(spiro[benzo[c]fluorine-7,9′-fluorene]-5,9-diylbis(4,1-phenylene))bis(1-phenyl-1H-benzo[d]imidazole) and 2,2′-(spiro[benzo-[de]anthracene-7,9′-fluorene]-2′,3-diylbis(4,1-phenylene))bis(1-phenyl-1H-benzo[d]imidazole), were prepared by a Suzuki coupling reaction. Their photophysical and photochemical properties were studied systemically. The fluorescent organic light-emitting diodes were fabricated by using them as the emitters, all of them showed strong blue emission. Interestingly, from the benzoanthracene derived compound a high color purity was found with Commission de L'Eclairage 1931 chromaticity coordinates of (0.15, 0.10) and an efficiency of 1.96 cd/A. To the best of our knowledge, this is the first time to obtain a deep-blue emission with spiro[benzofluorene] derivative in a nondoped device.

•The increased electron mobility in C60 films on DIP-template SiO2 substrate.•Decreased trap states in C60 films due to the improved C60 structure ordering on DIP-template SiO2 substrate.•Both increased domain size and molecular ordering of C60 films by using DIP-template.C60-based organic thin film transistors (OTFTs) with high electron mobility and high operational stability are achieved with (1 1 1) oriented C60 films grown by using template effects of diindenoperylene (DIP) under layer on the SiO2 gate insulator. The electron mobility of the C60 transistor is significantly increased from 0.21 cm2 V−1 s−1 to 2.92 cm2 V−1 s−1 by inserting the template-DIP layer. Moreover much higher operational stability is also observed for the DIP-template C60 OTFTs. A grazing incidence X-ray diffraction and ultrahigh-sensitivity photoelectron spectroscopy measurements indicate that the improved electron mobility and stability arise from the decreased density of trap states in the C60 film due to increased (1 1 1) orientation of C60-grains and their crystallinity on the DIP template.

•High-performance OFET memory based on nano-floating-gate is shown.•Memory window can be greatly enlarged upon illumination depending on incident photon energy.•The light effects include the minority multiplication effect and the excitation-induced injection effect.•Appropriate illumination is favorable for reducing programming/erasing voltage of OFET memory.A pentacene-based organic field-effect transistor nonvolatile memory, in which polystyrene covered Au nanoparticles act as the nano-floating-gate, is probed under different illumination conditions. The memory window can be greatly enlarged upon illumination depending on incident photon energy and intensity, and two light effects are proposed and discussed. The minority multiplication effect enhances the minority carrier tunneling into the nano-floating-gate, resulting in the remarkable positive VT shift. The excitation-induced injection effect is strongly photon energy dependent, and it is responsible for the significant negative VT shift. Appropriate illumination is favorable for reducing the programming/erasing voltage of organic nano-floating-gate nonvolatile memories.Graphical abstract

A spiro[benzoanthracene–fluorene] derivative containing a phenanthrene moiety, 2′,3-di(phenanthren-9-yl)spiro[benzo[de]anthracene-7,9′-fluorene] (DPSBAF), was prepared by a Suzuki coupling reaction. The photophysical and photochemical properties were investigated systematically. A non-doped organic light-emitting diode using DPSBAF as the emitter achieved a luminance efficiency of 2.18 cd A−1 with Commission Internationale de l'Éclairage 1931 chromaticity coordinates of (0.15, 0.09). The synthesized spiro[benzoanthracene–fluorene] derivative with a high thermal stability, a glass transition temperature of 210 °C and a decomposition temperature of 410 °C, shows potential for application in non-doped saturated deep-blue organic light-emitting diodes.

A one-pot universal approach with simple metal sputtering onto room temperature ionic liquids has been developed to prepare bimetal-nanoparticle (NP)-graphene hybrids, and the process is environmentally friendly and completely free of additives and byproducts. The graphene-supported bimetallic NPs have an Ag-based core and an Au/Pd-rich shell, demonstrated by the scanning transmission electron microscopy. The X-ray absorption near-edge spectroscopy using synchrotron radiation reveals the occurrence of charge redistribution at both the Ag@Au and Ag@Pd core–shell interfaces. The as-prepared Ag@Au and Ag@Pd bimetal-NP-graphene hybrids are highly catalytically active for reduction of 4-nitrophenol, whose catalytic activity is superior to the corresponding monometallic hybrids. The catalytic superiority is ascribed to the electronic structure modification and morphological irregularity of the graphene-supported bimetallic NPs.Keywords: bimetal nanoparticles; graphene; hybrid; room temperature ionic liquids; sputtering;

The electronic structure of graphdiyne exposed to air is investigated utilizing X-ray absorption spectroscopy and scanning transmission X-ray microscopy. It is found that carbon–carbon triple bonds at defect sites in graphdiyne have been changed to double bonds after 3 months in air. The experimental results reveal the existence of oxygen and nitrogen functional groups and indicate that the oxidation takes place throughout the aged graphdiyne while the nitrogen contamination is mainly on its surface. Buckling of the aged graphdiyne is observed, resulting from bond length change due to the opening of triple bonds. It is also shown that annealing at a high temperature such as 800 °C may remove most of the functional groups in the aged graphdiyne.

1,8-Naphthoylene(trifluoromethylbenzimidazole)-4,5-dicarboxylic acid imide (NTFBII) derivatives were synthesized. The OFET devices based on these new materials showed typical n-type OFET behavior and achieved an electron mobility as high as 0.10 cm2 V−1 s−1 with good bias stress stability.

The evolution of solid state N-doping in graphene has been probed using X-ray absorption near-edge structure (XANES) spectroscopy. The XANES spectra show that the modification of graphene with N species can be achieved by urea attachment at annealing temperatures lower than 300 °C. A transition from urea to amino species is observed at 400 °C. At higher temperatures, pyridinic and graphitic type doping are achieved. The results indicate that the electronic structure of graphene can be controlled by solid state treatment, involving different N species depending on the annealing process.

We report a generic strategy to make hybrids incorporating metal nanoparticles and carbon nanosupports with large surface area, which is a one-step, universal approach totally free of additives and by-products. Utilizing this approach, we show that small Au, Ag and Pd nanoparticles of uniform size can be self-assembled on diverse carbon nanostructures such as graphene oxide, reduced graphene oxide, and multiwalled carbon nanotubes by simply sputtering metal onto room-temperature ionic liquids. The size of metal nanoparticles can be controlled by the composition of room-temperature ionic liquids, and the surface density of metal nanoparticles can be controlled by the sputtering conditions. The self-assembly is demonstrated to be driven by the interlinking interactions among the metal nanoparticles, ionic liquid cations and carbon nanostructures.

We report a study on the contact resistance instability induced by the bias stress in staggered pentacene thin film transistors, combining the bias stress measurements with the transfer line method. The contact resistance is increasing with the stress time, and two device parameters are found to contribute to this contact resistance instability: one is the threshold voltage increase due to the charge trapping in the charge accumulation layer; the other is the effective contact length increase due to the charge trapping in the pentacene bulk in the contact region. The gold contact shows lower contact resistance stability compared with the copper contact, which is ascribed to higher density of the deep trap states at the gold contact. This work suggests that the time-dependent charge trapping is responsible for the bias stress effect in organic thin film transistors.Graphical abstractSchematics of current crowding behavior in a staggered OTFT (Left), and contact resistance change under bias stress condition (Right).Highlights► Bias stress effect in OTFTs involves both channel and contact resistance changes. ► Contact resistance is observed to be increasing with stress time. ► Threshold voltage shift contributes to the contact resistance change. ► Effective contact length change contributes to the contact resistance change. ► Time-dependent charge trapping may be responsible for bias stress effect in OTFTs.

We have investigated model systems of silver clusters with different sizes (3 and 15 atoms) deposited on alumina and titania supports using ambient pressure X-ray photoelectron spectroscopy. The electronic structures of silver clusters and support materials are studied upon exposure to various atmospheres (ultrahigh vacuum, O2 and CO) at different temperatures. Compared to bulk silver, the binding energies of silver clusters are about 0.55 eV higher on TiO2 and 0.95 eV higher on Al2O3 due to the final state effect and the interaction with supports. No clear size effect of the silver XPS peak is observed on different silver clusters among these samples. Silver clusters on titania show better stability against sintering. Al 2p and Ti 2p core level peak positions of the alumina and titania support surfaces change upon exposure to oxygen while the Ag 3d core level position remains unchanged. We discuss the origin of these core level shifts and their implications for catalytic properties of Ag clusters.

1,8-Naphthoylene(trifluoromethylbenzimidazole)-4,5-dicarboxylic acid imide (NTFBII) derivatives were synthesized. The OFET devices based on these new materials showed typical n-type OFET behavior and achieved an electron mobility as high as 0.10 cm2 V−1 s−1 with good bias stress stability.

In this work, ambient pressure X-ray photoelectron spectroscopy (APXPS) was used to investigate the effect of oxygen adsorption on the band bending and electron affinity of Al2O3, ZnO and TiO2 ultrathin films (∼1 nm in thickness) deposited on a Si substrate by atomic layer deposition (ALD). Upon exposure to oxygen at room temperature (RT), upward band bending was observed on all three samples, and a decrease in electron affinity was observed on Al2O3 and ZnO ultrathin films at RT. At 80 °C, the magnitude of the upward band bending decreased, and the change in the electron affinity vanished. These results indicate the existence of two surface oxygen species: a negatively charged species that is strongly adsorbed and responsible for the observed upward band bending, and a weakly adsorbed species that is polarized, lowering the electron affinity. Based on the extent of upward band bending on the three samples, the surface coverage of the strongly adsorbed species exhibits the following order: Al2O3 > ZnO > TiO2. This finding is in stark contrast to the trend expected on the surface of these bulk oxides, and highlights the unique surface activity of ultrathin oxide films with important implications, for example, in oxidation reactions taking place on these films or in catalyst systems where such oxides are used as a support material.

A novel approach to fabricate large-scale embedded metallic mesh transparent conductive electrodes (TCEs) on flexible substrates via a low-cost and facile selective electrodeposition process combined with inverted film-processing methods is proposed for the first time. The optimized embedded Ni mesh TCEs on polyethylene terephthalate (PET) exhibit excellent optoelectronic properties (Rs ∼ 0.2 Ω sq−1 & T ∼ 84%), high figure of merit (FOM ∼ 1.0 × 104) and mechanical durability properties, which arise from the embedded inverted T-type shape of the electrodeposited Ni mesh. The resultant embedded Ni mesh/polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hybrid electrodes are utilized both as current collectors and active electrode materials for all-solid-state flexible transparent supercapacitors, which show high transparency, superior electrochemical performances, excellent mechanical flexibility and high capacitance retention. Even after 1000 cycles of repetitive bending with a radius of 2 mm, the capacitance exhibited a decrease within only 5.2%. The high performance can be attributed to the excellent optoelectronic properties of embedded Ni mesh electrodes in combination with superior electrochemical properties of PEDOT:PSS. This provides a simple, cheap and controllable method for fabricating high-performance flexible TCEs and thus constructing flexible and transparent energy conversion and storage devices and systems.

Inverted organic light-emitting diodes (IOLEDs) can effectively improve device stability because they concentrate the air-stable anode and high work function (WF) metal oxide hole-injection layer (HIL) at the top of the devices. In this work, we report a facile solution-processed ultra-thin alumina film used as an electron-injection layer in IOLEDs and present significantly improved device performance. We achieved a high current efficiency of 5.12 cd A−1 at 10 mA cm−2 and the best current efficiency approaching 5.5 cd A−1 at 40 mA cm−2 without doping of an emission layer (EML) for a single Alq3-based green fluorescent IOLED, and a high current efficiency for a green phosphorescent IOLED as well. Furthermore, the extrapolated 50% decay lifetime (t50) shows that our Alq3-based green fluorescent IOLED is about 5 times more stable than the conventional OLED.