Surface coating of LiNi[Formula: see text]Mn[Formula: see text]Co[Formula: see text]O2 (NMC532) is an effective approach to improve the capacity retention and energy density through increasing cutoff operation voltage. In this work, NMC532 electrodes are directly coated with Ta2O5 via atomic layer deposition (ALD). The 5 cycles ALD-Ta2O5-coated electrodes have the significantly enhanced capacity cyclability. The high-quality amorphous ALD-Ta2O5 layer retards the interfacial reaction between NMC532 and electrolyte, and prevents the dissolution of the active materials, improving the phase stability of the NMC532 materials.

The magnetic function of layered molybdenum disulfide (MoS2) has been investigated via simulation, but few reliable experimental results have been explored. Herein, we developed edges-rich structural MoS2 nanosheets via liquid phase exfoliation approach, triggering exceptional ferromagnetism. The magnetic measurements revealed the clear ferromagnetic property of layered MoS2, compared to the pristine MoS2 in bulk exhibiting diamagnetism. The existence of ferromagnetism mostly was attributed to the presence of grain boundaries with abundant irregular edges confirmed by the transmission electron microscopy, magnetic force microscopy and X-ray photoelectron spectroscopy, which experimentally provided reliable evidences on irregular edges-rich states engineering ferromagnetism to clarify theoretical calculation.

A series of hexagonal Zn1−xCdxS photocatalysts with variable composition (0.2 ≤ x ≤ 1) is synthesized by a solvothermal method.

Ultrathin atomic-layer-deposited (ALD) vanadium oxide (VOx) interlayer has recently been demonstrated for remarkably reducing the contact resistance in organic electronic devices (Adv. Funct. Mater. 2016, 26, 4456). Herein, we present an in situ photoelectron spectroscopy investigation (including X-ray and ultraviolet photoelectron spectroscopies) of ALD VOx grown on pentacene to understand the role of the ALD VOx interlayer for the improved contact resistance. The in situ photoelectron spectroscopy characterizations allow us to monitor the ALD growth process of VOx and trace the evolutions of the work function, pentacene HOMO level, and VOx defect states during the growth. The initial VOx growth is found to be partially delayed on pentacene in the first ∼20 ALD cycles. The underneath pentacene layer is largely intact after ALD. The ALD VOx is found to contain a high density of defect states starting from 0.67 eV below the Fermi level, and the energy level of these defect states is in excellent alignment with the HOMO level of pentacene, which therefore allows these VOx defect states to provide an efficient hole-injection pathway at the contact interface.

The atomic layer deposition (ALD) of iron sulfide (FeSx ) is reported for the first time. The deposition process employs bis(N,N'-di-tert-butylacetamidinato)iron(II) and H2 S as the reactants and produces fairly pure, smooth, and well-crystallized FeSx thin films following an ideal self-limiting ALD growth behavior. The FeSx films can be uniformly and conformally deposited into deep narrow trenches with aspect ratios as high as 10:1, which highlights the broad applicability of this ALD process for engineering the surface of complex 3D nanostructures in general. Highly uniform nanoscale FeSx coatings on porous γ-Al2 O3 powder were also prepared. This compound shows excellent catalytic activity and selectivity in the hydrogenation of azo compounds under mild reaction conditions, demonstrating the promise of ALD FeSx as a catalyst for organic reactions.

The magnetocaloric properties of an electron-doped manganite Ca0.88Dy0.12MnO3 have been studied in detail. A reversible magnetocaloric effect has been observed at the Curie temperature T-C of 100 K, which is related to a second order magnetic transition from paramagnetic to ferromagnetic state. The values of maximum magnetic entropy change can reach 0.82 and 1.92 J kg(-1) K-1 for a field change of 2 and 5 T, respectively, with no obvious hysteresis loss in the vicinity of the Curie temperature. The magnetic entropy change can be well described by the recently proposed phenomenological universal behavior. This result can shed light on the design of magnetic refrigerators in engineering. (c) 2016 Elsevier B.V. All rights reserved.

A crack-free (InNb)0.1Ti0.9O2 single crystal of 4mm in diameter and 30mm in length was successfully grown by the optical floating zone method. The polycrystalline feed and seed rods for growing the (InNb)0.1Ti0.9O2 single crystal were prepared by solid-state reaction method. The oxygen partial pressure significantly affected the crystal quality of the material. As shown in reflecting polarizing microphotographs, crystals grown in air have fewer grain boundaries than those grown in pure oxygen; some air-grown crystals are completely free of grain boundaries. Compared to pure TiO2 crystal, the (Nb+In) co-doped TiO2 crystal required a lower growth rate of 5mm/h to ensure high quality.

The present work intends to explain why ultrathin Al2O3 atomic-layer-deposited (ALD) on the back contact with rectification and tunneling effects can significantly improve the performance of CdTe solar cells in our previous work [ Liang , J. ; et al. Appl. Phys. Lett. 2015 , 107 , 013907 ]. Herein, we further study the mechanism through establishing the interfacial energy band diagram configuration of the ALD Al2O3/CuxTe by experiment of X-ray photoelectron spectroscopy and first-principles calculations and conclude to find the band alignment with optimized layer thickness (about 1 nm ALD Al2O3) as the key factor for rectification and tunneling effects.

Vapor-phase atomic layer deposition (ALD) of nickel sulfide (NiSx) is comprehensively reported for the first time. The deposition process employs bis(N,N'-di-tert-butylacetamidinato)nickel(II) and H2S as the reactants and is able to produce fairly smooth, pure, godlevskite-structured NiSx thin films following an ideal layer-by-layer ALD growth fashion for a relatively wide process temperature range from 90-200 degrees C. Excellent conformal coating is demonstrated for this ALD process, as the deposited NiSx films are able to uniformly and conformally cover deep narrow trenches with aspect ratio as high as 10:1, which highlights the general and broad applicability of this ALD process for fabricating complex 3D-structured nanodevices. Further, we demonstrate the applications of this ALD NiSx for oxygen-evolution reaction (OER) electrocatalysis. The ALD NiSx is found to convert to nickel (oxy)hydrate after electrochemical aging, and the aged product shows a remarkable electrocatalytic activity and long-term stability, which is among the best electrocatalytic performance reported for nonprecious OER catalysts. Considering that ALD can be easily scaled up and integrated with 3D nanostructures, we believe that this ALD NiSx process will be highly promising for a variety of applications in future energy devices.

Charge injection at metal/organic interface is a critical issue for organic electronic devices in general as poor charge injection would cause high contact resistance and severely limit the performance of organic devices. In this work, a new approach is presented to enhance the charge injection by using atomic layer deposition (ALD) to prepare an ultrathin vanadium oxide (VOx) layer as an efficient hole injection interlayer for organic field‐effect transistors (OFETs). Since organic materials are generally delicate, a gentle low‐temperature ALD process is necessary for compatibility. Therefore, a new low‐temperature ALD process is developed for VOx at 50 °C using a highly volatile vanadium precursor of tetrakis(dimethylamino)vanadium and non‐oxidizing water as the oxygen source. The process is able to prepare highly smooth, uniform, and conformal VOx thin films with precise control of film thickness. With this ALD process, it is further demonstrated that the ALD VOx interlayer is able to remarkably reduce the interface contact resistance, and, therefore, significantly enhance the device performance of OFETs. Multiple combinations of the metal/VOx/organic interface (i.e., Cu/VOx/pentacene, Au/VOx/pentacene, and Au/VOx/BOPAnt) are examined, and the results uniformly show the effectiveness of reducing the contact resistance in all cases, which, therefore, highlights the broad promise of this ALD approach for organic devices applications in general.

As a compound analogue of black phosphorus, a new 2D semiconductor of SnS layers is proposed. Based on state-of-the-art theoretical calculations, we confirm that such 2D SnS layers are thermally and dynamically stable and can be mechanically exoliated from alpha-phase SnS bulk materials. The 2D SnS layer has an indirect band gap that can be tuned from 1.96 eV for the monolayer to 1.44 eV for a six-layer structure. Interestingly, the decrease of the band gap with increasing number of layers is not monotonic but shows an odd-even quantum confinement effect, because the interplay of spin-orbit Coupling and lack of inversion symmetry in odd-numbered layer structures results in anisotropic spin splitting of the energy bands. It was also found that such 2D SnS layers show high in-plane anisotropy and high carrier mobility (tens of thousands of cm(2) V-1 s(-1)) even superior to that of black phosphorus, which is dominated by electrons. With these intriguing electronic properties, such 2D SnS layers are expected to have great potential for application in future nano electronics.

Understanding and optimizing the temperature effects of Li‐ion diffusion by analyzing crystal structures of layered Li(NixMnyCoz)O2 (NMC) (x + y + z = 1) materials is important to develop advanced rechargeable Li‐ion batteries (LIBs) for multi‐temperature applications with high power density. Combined with experiments and ab initio calculations, the layer distances and kinetics of Li‐ion diffusion of LiNixMnyCozO2 (NMC) materials in different states of Li‐ion de‐intercalation and temperatures are investigated systematically. An improved model is also developed to reduce the system error of the “Galvanostatic Intermittent Titration Technique” with a correction of NMC particle size distribution. The Li‐ion diffusion coefficients of all the NMC materials are measured from −25 to 50 °C. It is found that the Li‐ion diffusion coefficient of LiNi0.6Mn0.2Co0.2O2 is the largest with the minimum temperature effect. Ab initio calculations and XRD measurements indicate that the larger Li slab space benefits to Li‐ion diffusion with minimum temperature effect in layered NMC materials.

Increasing the open-circuit voltage (Voc) along with the fill factor (FF) is pivotal for the performance improvement of solar cells. In this work, we report the design and construction of a new structure of CdS/CdTe/Al2O3/Cu using the atomic layer deposition (ALD) method, and then we control Cu diffusion through the Al2O3 atomic layer into the CdTe layer. Surprisingly, this generates a novel p-type and metallic dual-functional Cu-Al2O3 atomic layer. Due to this dual-functional character of the Cu-Al2O3 layer, an efficiency improvement of 2% in comparison with the standard cell was observed. This novel dual-functional back contact structure could also be introduced into other thin film solar cells for their efficiency improvement.

High-voltage (>4.3 V) operation of LiNi(x)Mn(y)Co(z)O2 (NMC; 0 ≤ x, y, z < 1) for high capacity has become a new challenge for next-generation lithium-ion batteries because of the rapid capacity degradation over cycling. In this work, we investigate the performance of LiNi(0.5)Mn(0.3)Co(0.2)O2 (NMC532) electrodes with and without an atomic-layer-deposited (ALD) Al2O3 layer for charging/discharging in the range from 3.0 to 4.5 V (high voltage). The results of the electrochemical measurements show that the cells with ALD Al2O3-coated NMC532 electrodes have much enhanced cycling stability. The mechanism was investigated by using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, and electrochemical methods. We find that the ultrathin ALD Al2O3 film can reduce the interface resistance of lithium-ion diffusion and enhance the surface stability of NMC532 by retarding the reactions at NMC532/electrolyte interfaces for preventing the formation of a new microstructure rock-salt phase NiO around the NMC532 surfaces.

The synthesis of ZnO with tailorable shapes and point defects is important for its potential applications. Here, a facile approach is demonstrated to prepare ZnO nanocages with controllable porous shell structures though sintering a Zn‐based cyanide‐bridged coordination polymer under different temperatures. The transformation of ZnCP microspheres into ZnO nanocages is based on two types of nanoscale Kirkendall effect, which are related to low temperature solid–solid interfacial oxidation and high temperature solid–gas interfacial reaction, respectively. At low temperature (around 300 °C) and before the ZnCP decomposition, the novel “hierarchical ZnO bigger nanocages embedded with smaller nanocages with 10 nm nanocrystals” can be generated. By contrast, when coming to the total decomposition of ZnCP at 800 °C, ZnO nanocages with significantly increased sizes and large cavities are generated, and large amounts of oxygen vacancies (VO) are created at the same time, leading to the dramatic increased luminescence intensities of the UV peak due to VO at 540 nm. Thus, the luminescence intensities versus defect concentration in the prepared ZnO nanocages can also be controlled by tuning the sintering temperatures.

Atomic layer deposition (ALD) of cobalt sulfide (Co9S8) is reported. The deposition process uses bis(N,N'-diisopropylacetamidinato)cobalt(II) and H2S as the reactants and is able to produce high-quality Co9S8 films with an ideal layer-by-layer ALD growth behavior. The Co9S8 films can also be conformally deposited into deep narrow trenches with aspect ratio of 10:1, which demonstrates the high promise of this ALD process for conformally coating Co9S8 on high-aspect-ratio 3D nanostructures. As Co9S8 is a highly promising electrochemical active material for energy devices, we further explore its electrochemical performance by depositing Co9S8 on porous nickel foams for supercapacitor electrodes. Benefited from the merits of ALD for making high-quality uniform thin films, the ALD-prepared electrodes exhibit remarkable electrochemical performance, with high specific capacitance, great rate performance, and long-term cyclibility, which highlights the broad and promising applications of this ALD process for energy-related electrochemical devices, as well as for fabricating complex 3D nanodevices in general.

We report the multiferroic properties of 12R-type hexagonal Ba(Ti1/3Mn2/3)O3-δ found in Mn-doped BaTiO3 series samples. Hysteresis measurements reveal the coexistence of weak ferromagnetism and ferroelectricity at room temperature. Furthermore, frequency-driven dynamic ferroelectric phase transition is disclosed around a critical frequency of 220 Hz. Analyses on the dielectric relaxation, leakage current, crystal structure, and magnetic susceptibility lead us to conclude that the response of polarons dominates the observed physical properties, and the dynamic phase transition may ascribe to the response mode changes of the localized electrons. More importantly, we figure out the crucial factors leading to difference of the ferroelectric and magnetic properties of the 12R-type Ba(Ti1/3Mn2/3)O3-δ samples from that of the 6H-type Ba(Ti1-xMx)O3-δ (M = Fe, Mn) samples.

Atomic layer deposition (ALD) of Aluminum oxide (Al2O3) is employed to optimize the back contact of thin film CdTe solar cells. Al2O3 layers with a thickness of 0.5 nm to 5 nm are tested, and an improved efficiency, up to 12.1%, is found with the 1 nm Al2O3 deposition, compared with the efficiency of 10.7% without Al2O3 modification. The performance improvement stems from the surface modification that optimizes the rectification and tunneling of back contact. The current-voltage analysis indicates that the back contact with 1 nm Al2O3 maintains large tunneling leakage current and improves the filled factor of CdTe cells through the rectification effect. XPS and capacitance-voltage electrical measurement analysis show that the ALD-Al2O3 modification layer features a desired low-density of interface state of 8 × 1010 cm−2 by estimation.