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The efficient cleavage of the N≡N bond is vital to N2 fixation but remains challenging. In this issue of Chem, Zhang and co-workers report that the interfacial polarization fields triggered by protrusion-shaped Fe single atoms on monolayer MoS2 can promote N≡N splitting via electron injection, resulting in a praiseworthy nitrogen electroreduction.

Dye-sensitized solar cells and photocatalysts that consist of a light-absorbing dye and a wide gap oxide semiconductor substrate have been studied extensively as a means of solar energy conversion....

The early photophysical events occurring in the dinuclear metal complex [(ttb-terpy)(I)Ru(μ-dntpz)Ru(bpy)2]3+ (2; ttb-terpy = 4,4',4''-tri-tert-butyl-terpy; bpy = 2,2'-bipyridine; dntpz = 2,5-di-(1,8-dinaphthyrid-2-yl)pyrazine) - a species containing the chromophoric {(bpy)2Ru(μ-dntpz)}2+ subunit and the catalytic {(I)(ttb-terpy)Ru(μ-dntpz)}+ unit, already reported to be able to perform photocatalytic water oxidation - have been studied by ultrafast pump-probe spectroscopy in acetonitrile solution. The model species [Ru(bpy)2(dntpz)]2+ (1), [(bpy)2Ru(μ-dntpz)Ru(bpy)2]4+ (3), and [(ttb-terpy)(I)Ru((μ-dntpz)Ru[(ttb-terpy)(I)]2+ (4) have also been studied. For completeness, the absorption spectra, redox behavior of 1-4 and the spectroelectrochemistry of the dinuclear species 2-4 have been investigated. The usual 3MLCT (metal-to-ligand charge transfer) decay, characterized by relatively long lifetimes on the ns timescale, takes place in 1 and 3, whose lowest-energy level involves a {(bpy)2Ru(dntpz)}2+ unit, whereas for 2 and 4, whose lowest-energy excited state involves a 3MLCT centered on the {(I)(ttb-terpy)Ru(μ-dntpz)}+ subunit, the excited-state lifetimes are on the ps timescale, possibly involving population of a low-lying 3MC (metal-centered) level. Compound 2 also exhibits a fast process, with a time constant of 170 fs, which is attributed to intercomponent energy transfer from the MLCT state centered in the {(bpy)2Ru(μ-dntpz)}2+ unit to the MLCT state involving the {(I)(ttb-terpy)Ru(μ-dntpz)}+ unit. Both the intercomponent energy transfer and the MLCT-to-MC activation process take place from non-equilibrated MLCT states.

Inverted top-emitting organic light-emitting devices (TEOLEDs) have great potential in flat-panel displays and lighting, yet poor electron injection is a key issue limiting its use in active-matrix OLED. Here, a high-performance green phosphorescent inverted TEOLEDs with ZnO and ZnS double electron injection layers (EILs) were demonstrated. The double EILs which provide a work function gradient can greatly enhance the electron-injection efficiency. For the green phosphorescent TEOLED device based on this double EILs, a high current efficiency of 33.1 cd A−1 is achieved with low turn-on voltage of 4.0 V. Results indicate that a novel pathway of electron transport to accelerate electron injection is created by applying this double EILs.

Solar-driven production of renewable energy (e.g., H2) has been investigated for decades. To date, the applications are limited by low efficiency due to rapid charge recombination (both radiative and nonradiative modes) and slow reaction rates. Tremendous efforts have been focused on reducing the radiative recombination and enhancing the interfacial charge transfer by engineering the geometric and electronic structure of the photocatalysts. However, fine-tuning of nonradiative recombination processes and optimization of target reaction paths still lack effective control. Here we show that minimizing the nonradiative relaxation and the adsorption energy of photogenerated surface-adsorbed hydrogen atoms are essential to achieve a longer lifetime of the charge carriers and a faster reaction rate, respectively. Such control results in a 16-fold enhancement in photocatalytic H2 evolution and a 15-fold increase in photocurrent of the crystalline g-C3N4 compared to that of the amorphous g-C3N4.

Using hot electrons to drive electrochemical reactions has drawn considerable interest in driving high-barrier reactions and enabling efficient solar to fuel conversion. However, the conversion efficiency from hot electrons to electrochemical products is typically low due to high hot electron scattering rates. Here, it is shown that the hydrogen evolution reaction (HER) in an acidic solution can be efficiently modulated by hot electrons injected into a thin gold film by an Au-Al

For efficient electron injection, a method to control the work functions (WFs) of ZnO electrodes in organic light-emitting devices (OLEDs) is reported in this study. First, ZnO was modified by doping of tetraalkylammonium salts (TRAX) into polyethylenimine ethoxylated (PEIE) for the WF control. Tetrabutylammonium salts (TBAX), where X = chloride, bromide, iodide, acetate, thiocyanate, and tetrafluoroborate anions, were doped into PEIE. A WF of nondoped PEIE-modified ZnO was 3.65 eV, whereas TBAX-doped PEIE-modified ZnO exhibited WFs ranging from 3.52 to 3.00 eV depending on the anion. TBAX salts exhibited different electron-donating capabilities depending on the anion, and the doping of TBAX with a large electron-donating capability exhibited a large WF reduction effect. In addition, tetraethyl- and tetrahexylammonium chlorides were doped into PEIE. PEIE doped with TRACl containing long alkyl chains exhibited a large WF reduction effect due to its low electron-accepting capabilities. In addition, the WF reduction mechanism was considered by the depth direction analysis of the PEIE:TBAX films. Finally, the ZnO/PEIE:TRAX bilayers were applied as electron injection layers in poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] emissive-layer-based OLEDs with an inverted structure. The ZnO/PEIE:TBAX devices with low WFs exhibited low driving voltages.

Organic phototransistors (OPTs) have been extensively investigated as photodetectors because of their internal photocurrent amplification. However, OPTs tend to show high dark current because they ...

The spectral sensitization of single-crystal p-GaP by semiconducting single-walled carbon nanotubes (s-SWCNT) via hole injection into the p-GaP valence band is reported. The results are compared to SWNCT sensitized n-type single-crystal substrates: TiO2, SnO2, and n-GaP. It was found that the sensitized photocurrents from CoMoCAT and HiPco s-SWCNTs were from a hole injection mechanism on all substrates, even when electron injection into the conduction band should be energetically favored. The results suggest an intrinsic p-type character of the s-SWCNTs surface films investigated in this work.

Inverted organic light-emitting diodes (iOLEDs) without the use of alkali metals have attracted extensive attention owing to the demand for the realization of flexible OLEDs that do not require stringent encapsulation. In this paper, we discuss the correlation between the characteristics of iOLEDs and the energy-level alignment at cathode/organic layer interfaces examined by ultraviolet photoelectron spectroscopy. Two similar electron-transporting materials having different orbital energies, 2,8-bis(diphenylphosphoryl)dibenzo[ b, d]thiophene (PPT) and 2,8-bis(diphenylphosphoryl)dibenzo[ b, d]thiophene sulfone (PPT-S), are inserted between the cathode/polyethyleneimine and the emitting layer in the iOLED. The iOLED employing PPT-S exhibits a lower driving voltage and a higher efficiency than that employing PPT, which is consistent with the orbital energies of the two molecules. Although the stabilities of these two molecules are expected to be similar, the iOLED employing PPT-S exhibits an operational lifetime that is more than 100 times longer than that of the iOLED employing PPT. It was found that the difference in operational lifetime is caused by the difference in the energy-level alignment at the cathode/organic layer interfaces. Our results are expected to promote the development of promising materials and device configurations for fabricating efficient and operationally stable iOLEDs.

A little more than a monolayer-thick pure-boron (PureB) layer was deposited on silicon at 250 °C by chemical vapor deposition (CVD), forming junctions with low saturation current. They displayed the same efficient suppression of electron injection as PureB diodes fabricated with a few nm-thick PureB layer deposited at 400 °C. Assuming high concentrations of acceptor states at the B-to-Si interface, induced by a fixed negative charge in the range from $\textsf {5}\times \textsf {10}^{\textbf {13}}$ cm $^{-\textbf {2}}$ to $\textsf {5}\times \textsf {10}^{\textbf {14}}$ cm $^{-\textbf {2}}$ , would be consistent with the experiments and device simulations that exhibit an efficient suppression of electron injection. Metallization of the B-layers was studied, showing that in many situations, thinning of the layer to monolayer thickness will lead to a significant increase in the electron injection.

Accepted: 2019-04-22, 資料番号: SA1190074000

Engineered nanomaterials (ENMs) have been developed for imaging, drug delivery, diagnosis, and clinical therapeutic purposes because of their outstanding physicochemical characteristics. However, the function and ultimate efficiency of nanomedicines remain unsatisfactory for clinical application, mainly because of our insufficient understanding of nanomaterial/nanomedicine-biology (nano-bio) interactions. The nonequilibrated, complex, and heterogeneous nature of the biological milieu inevitably influences the dynamic bioidentity of nanoformulations at each site (i.e., the interfaces at different biological fluids (biofluids), environments, or biological structures) of nano-bio interactions. The continuous interplay between a nanomedicine and the biological molecules and structures in the biological environments can, for example, affect cellular uptake or completely alter the designed function of the nanomedicine. Accordingly, the weak and strong driving forces at the nano-bio interface may elicit structural reconformation, decrease bioactivity, and induce dysfunction of the nanomaterial and/or redox reactions with biological molecules, all of which may elicit unintended and unexpected biological outcomes. In contrast, these driving forces also can be manipulated to mitigate the toxicity of ENMs or improve the targeting abilities of ENMs. Therefore, a comprehensive understanding of the underlying mechanisms of nano-bio interactions is paramount for the intelligent design of safe and effective nanomedicines. In this Account, we summarize our recent progress in probing the nano-bio interaction of nanomedicines, focusing on the driving force and redox reaction at the nano-bio interface, which have been recognized as the main factors that regulate the functions and toxicities of nanomedicines. First, we provide insight into the driving force that shapes the boundary of different nano-bio interfaces (including proteins, cell membranes, and biofluids), for instance, hydrophobic, electrostatic, hydrogen bond, molecular recognition, metal-coordinate, and stereoselective interactions that influence the different nano-bio interactions at each contact site in the biological environment. The physicochemical properties of both the nanoparticle and the biomolecule are varied, causing structure recombination, dysfunction, and bioactivity loss of proteins; correspondingly, the surface properties, biological functions, intracellular uptake pathways, and fate of ENMs are also influenced. Second, with the help of these driving forces, four kinds of redox interactions with reactive oxygen species (ROS), antioxidant, sorbate, and the prosthetic group of oxidoreductases are utilized to regulate the intracellular redox equilibrium and construct synergetic nanomedicines for combating bacteria and cancers. Three kinds of electron-transfer mechanisms are involved in designing nanomedicines, including direct electron injection, sorbate-mediated, and irradiation-induced processes. Finally, we discuss the factors that influence the nano-bio interactions and propose corresponding strategies to manipulate the nano-bio interactions for advancing nanomedicine design. We expect our efforts in understanding the nano-bio interaction and the future development of this field will bring nanomedicine to human use more quickly.

Excited electron transfer across semiconductor–molecule heterogeneous interfaces is central to various future electronic and optoelectronic devices. At the same time, first-principles modeling of s...

Aggregation induced emission enhancement (AIEE) of newly synthesized (E)-2-(((2-(1-(2,3-dihydrobenzo[b] [1,4] dioxin-5-yl)-1H-phenanthro[9,10-d]imidazol-2-yl)phenyl)imino) methyl)naphthalen-1-ol (HBDPPIN) was analyzed in aqueous media. The AIEE active HBDPPIN in aggregated state exhibit turn-off emission with Cu2+ whereas HBDPPIN-Cu2+ complex reveal turn-on fluorescence with Al3+. The detection limit was calculated as 4.13 × 10–2 μM for Cu2+ and 9.4 × 10−1 μM for Al3+. The interfacial carrier transfer in the fabricated Cu-TiO2-HBDPPIN-Ag film depends on the interfacial contact of the layers: hole injection barrier of EAg-HBDPPIN > ETiO2-HBDPPIN, however, the electron injection barrier of ETiO2-HBDPPIN → C T HBDPPIN → C T TiO2 is the predominant charge transfer direction in Cu-TiO2-HBDPPIN-Ag film. The binding energy/energy gap (Eb /Eg) of HBDPPIN-CuO composites dependent on the nature of CuO cluster and carrier transfer in HBDPPIN-Cu6O6 composite is faster than other composites.

Polyacrylonitrile (PAN) was adsorbed onto the TiO2 surface, and the resulting photoelectrodes were applied in dye-sensitized solar cells (DSSCs). The DSSC with the PAN-modified TiO2 showed an increase in its short-circuit current (Jsc) and a decrease in its open-circuit voltage (Voc), resulting in a 17% enhancement of its photovoltaic performance when compared to the reference cell. By incorporating PAN onto the surface of the TiO2, a surface dipole was formed, which induced a conduction band edge shift of the TiO2 in a positive direction. This shift led to a considerable improvement in the electron injection efficiency, and hence the Jsc.

The steady-state photoluminescence (PL) of CsPbBr3 films with varying thicknesses was studied under light-soaking on semiconductive and insulating contacts, showing reversible changes in PL, entirely dependent on the nature of the contact and film thicknesses. The PL at 50–100 nm CsPbBr3 on TiO2 increased, and decreased in thicker layers, with no thickness-dependent PL in CsPbBr3 on glass/Al2O3. These observations are described using a spatial charge distribution model which interprets the migration of Br– and VBr+ under light-soaking as suppressing electron injection into the TiO2 due to upward band bending, enhancing PL at the interface and nonradiative recombination further away from it.

The paper is devoted to developing the theoretical basis of the mathematical modelling and computer simulation intended to analyze and control the electron beam-stimulated effects in ferroelectric materials. In order to simulate the electron beam-induced charging dynamics of ferroelectrics the modification of drift-reaction-diffusion model was proposed. The calculation was based on the numerical solution of the continuity equation and Poisson equation. The parameters of the electron irradiation doze and source function were estimated by 3D Monte-Carlo simulation of electron trajectories in the solid specimen. The computation was associated with typical ferroelectrics (LiNbO3, LiTaO3) irradiated by intermediate-energy electron bunches specified for SEM. The contribution roles of drift component as well as diffusion component during dynamic charging process were discussed. The simulation results enable us to predict charge distribution, dynamic of the potential distribution, electric field and electron beam-induced component of polarization at the given experimental parameters. These findings can be used to control polarization switching in ferroelectrics electron beam-irradiated by the SEM techniques.

Inspired by the successful application of heterocyclic components as robust anchoring groups in porphyrin dyes, we designed three novel organic analogues utilizing indenoperylene-based dye C275 as the skeleton prototype and three different heterocyclic units as anchoring groups in this research. In light of the theoretical studies on these three investigated dyes and the corresponding dye/(TiO2)38 compounds, two heterocyclic units (tropolone and 8-carboxylquinoline) were screened as alternative anchoring groups for dye-sensitized solar cells (DSCs). Especially, An1 and An2 dyes based on these two anchoring units show their remarkable performances in interfacial properties compared to those of C275 dye, involving larger conduction band CB up-shift (An1/(TiO2)38, ΔECB = 0.23eV and An2/(TiO2)38, ΔECB = 0.20eV) system, distinguished balance between the electron injection rate (An1/(TiO2)38, kinj = 8.71 × 1014 s−1 and An2/(TiO2)38, kinj = 8.52 × 1014 s−1) and electron–hole recombination (An1/(TiO2)38, krec = 1.63 × 107 s−1 and An2/(TiO2)38, krec = 2.75 × 107 s−1). Therefore, this work may be supplied several promising candidate for experimental synthesis in organic dye sensitized solar cells.

The operating lifetime of blue quantum-dot light-emitting diodes (QLED) is currently a short slab for this emerging display technology. To pinpoint the origin of device degradation, here we apply multiple techniques to monitor the electric-field distribution and space-charge accumulation across the multilayered structure before and after lifetime tests. Evident by charge-modulated electro-absorption and capacitance-voltage characteristics, the excited electrons in blue quantum dots (QD) are prone to cross the type II junction between the QD emission layer and the electron-transporting layer (ETL) due to the offset of conduction band minimum, leading to space-charge accumulation and operating-voltage rise in the ETL. Therefore, unlike those very stable red devices, of which the lifetime is primarily limited by the slow degradation of hole-transporting layer, the poor lifetime of blue QLED originates from the fast degradation at the QD-ETL junction. Materials engineering for efficient electron injection is prerequisite for the boost of operating lifetime., Wide application of quantum dot light emitting diodes (QLED) in display technology is hindered by the poor lifetime of the blue QLEDs. Here, the degradation mechanism is shown to originate from space charge accumulation in the electron-transporting layer enabling improvements in blue QLED lifetimes.

Polystyrene sulfonate (PSS) functionalized ZnO nanowires were hydrothermally synthesized and assembled into a UV-activated optoelectronic NO2 sensor for the first time. In situ PSS functionalization during hydrothermal synthesis not only facilitated the formation of high-quality ZnO nanowires with small diameters and high aspect ratios, but also significantly improved the UV photoconductance of ZnO nanowires through photo-induced electron injection, leading to the enhanced optoelectronic properties of ZnO nanowires. The optoelectronic NO2 sensors based on PSS-functionalized ZnO nanowires showed much higher responses and faster response rates under UV illumination at room temperature (25 °C). The responses ranged from 60% to 690% toward NO2 concentrations of 50 ppb to 2 ppm. Moreover, the optoelectronic sensors exhibited excellent reversibility, good stability and a low detection limit (5 ppb), making the efficient, optically controlled sensing of ppb-level NO2 gas possible.

The Schottky barrier height (SBH) is a critical parameter that determines the carrier transfer at metal/semiconductor interfaces. In this work, the interfacial properties of Hf2NT2/MSSe (T = F, O, OH; M = Mo, W) heterostructures are systematically investigated using first-principles calculations. It is found that, for MoSSe and WSSe, the use of S or Se atomic layers in contact with Hf2NT2 can give significantly different SBHs. In addition, SB-free contact for electron injection can be realized for F–S interfaces in Hf2NF2/MoSSe and Hf2NF2/WSSe heterostructures. Furthermore, the SBHs of the heterostructures can be tuned by applying compressive strain and p-type ohmic contact can be obtained for O–Se interfaces in Hf2NO2/MoSSe and Hf2NO2/WSSe heterostructures. This work proposes a feasible strategy to regulate the SBHs of interfaces.

This study investigates low-temperature cross-linking of polyethyleneimine ethoxylated (PEIE) using four types of silane coupling agents, including trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TTSPAC), trimethoxyphenylsilane (TMPS), trimethoxy[3-(phenylamino)propyl]silane (TPAPS) and 1,2-bis(trimethoxysilyl)ethane (BTMSE). The results of this study indicated that all the silane coupling agents reacted with PEIE at low temperatures ranging from 65 to 120 °C. The reacted PEIE exhibited solvent tolerance, indicating the cross-linking of PEIE. The cross-linked PEIE films were applied to electron injection layers (EILs) in solution-processed organic light-emitting devices. The device with PEIE: TTSPAC EIL showed a shorter device lifetime than that with only PEIE EIL. The shorter device lifetimes were attributed to the migration of chloride anions of TTSPAC. Conversely, the devices with PEIE: TMPS, TPAPS and BTMSE EILs, which did not contain mobile ions, had longer device lifetimes than that with only PEIE EIL. These results suggested that these improvements of device stability resulted from the cross-linking of PEIE.

Two new carboxylated 1,3-indanedione sensitizers (MPhe-ind and BPhe-ind) were synthesized and their dye-sensitized solar cells (DSSC) performance were compared with the corresponding standard cyanoacetic acid sensitizers (MPhe-cn and BPhe-cn). The carboxylated 1,3-indanedione sensitizers have shown almost 100 nm enhanced absorption curves compared to the cyanoacetic acid dyes with an extended IPCE curve up to 800 nm. Despite greater absorption and electrochemical properties, the synthesized dyes showed moderate efficiencies (2.10% and 2.67%) than standard dyes. The low electron injection efficiency and recombination of carboxylated 1,3-indanedione might be responsible for low efficiency. Detailed investigation studies have been performed and complemented with the theoretical studies.

We have explored the influence of supplementary electron injection on the operational parameters of a planar magnetron operating in repetitively pulsed mode (repetition rate 300 Hz, pulse duration 50–100 μs). The supplementary electron flux was provided from the plasma of an auxiliary hollow-cathode glow discharge and was accelerated directly into the magnetron cathode layer. We show that this supplementary electron injection eliminates magnetron ignition delay and increases the sputtered ion current from the magnetron plasma.

The effect of a series of triarylamine based D-pi-A organic dyes, namely RK1, BA504, BA741 and the simple L1 reference dye on solid-state dye sensitized solar cells (s-DSSCs) performances was studied. The solid hole transporting material (HTM) was obtained by in-situ photoelectrochemical polymerization (in-situ PEP) process applied in two different media (water and acetonitrile) to produce the poly-3,4 ethylenedioxythiophene (PEDOT) conducting polymer (CP). A joint experimental and theoretical (density functional theory and time-dependent density functional theory) study is conducted to correlate the dye molecular structure containing different donor, pi-bridge or acceptor with several physicochemical characteristics such as optical (absorption and emission), electronic and redox properties of dyes in organic and aqueous medium; in-situ PEP process and charge transfer kinetics at the DSSC interfaces (Dye/TiO2 and Dye/HTM) through the alignment of the different energy levels of the dyes and electrodes. These properties are considered since they govern the performance of s-DSSCs denoted by the short-circuit current (J(sc)), open circuit cell potential (V-oc) and fill factor (FF). Among the four studied dyes, the s-DSSCs based on RK1, shows the best power conversion efficiency of 1.75% resulting from highest FF (0.57), V-oc (550 mV) and J(sc) (5.6 mA/cm(2)). The large differences in experimental photovoltaic performances of the obtained s-DSSCs have been well outlined and provide the guidelines for future development of more efficient solar-cell sensitizers.

In this work, we systematically investigate the impacts of electron-donor based on Triphenylamine (TPA). The Geometry structure, energy levels, light-harvesting ability and ultraviolet-visible absorption spectra were calculated by using Density Functional Theory (DFT) and Time-Dependent-DFT. The electron injection rate of the TPA-N(CH3)2 based dyes has 0.71 eV for high among the dye sensitizer. The First and Second order Hyperpolarizability of the 11.95 × 10−30 e.s.u and 12195.54 a.u, respectively for TPA-N(CH3)2 based dye. The calculated absorption spectra were showed in the ultra-violet visible region for power conversion region. The study reveals that the electron transfer character of TPA-N(CH3)2 based dyes can be made suitable for applications in Dye-Sensitized Solar Cells.