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A Sn2+ based oxide, SnTiO3, both in the ilmenite and the amorphous phase, is identified as a hole dopable and high mobility p-type oxide.

Among various intergranular microstructures, pore spaces in SEs play a critical role in Li-metal nucleation in SEs. To realize Li-metal nuclei-free inside the SE, removing pore spaces is essential and a commonly applicable design strategy to all SEs.

Discovery of ferroelectricity in HfO

First-principles calculations show a reduced energy barrier for polarization switching via a bulk phase transition by doping of hafnium-zirconium oxide (HZO). The tetragonal

The development of high-performance p-type oxides with wide band gap and high hole mobility is critical for the application of oxide semiconductors in back-end-of-line (BEOL) complementary metal-oxide-semiconductor (CMOS) devices. SnO has been intensively studied as a high-mobility p-type oxide due to its low effective hole mass resulting from the hybridized O-2p/Sn-5s orbital character at the valence band edge. However, SnO has a very small band gap (∼0.7 eV) for practical p-type oxide devices. In this work, we report an engineering method to enhance the band gap and hole mobility in SnO. It is found that both the band gap and the hole mobility of a layer-structured SnO increase with the interlayer stacking spacing change. By exploiting this unique electronic structure feature, we propose expanding the interlayer spacing by interlayer intercalation to engineer the band gap and p-type mobility in SnO. Small molecules like NH

2D metallic materials offer a solution to the problem of poor scalability of elemental metals within ever-downscaling device interconnects. With the absence of surface scattering, they could be used for interconnects in future integrated circuits.

The use of a heavier noble gas such as Kr in atomic layer annealing results in higher crystallinity due to higher momentum transfer leading to a more localized and intense surface heating effect occurring over picosecond timescales.

O substitution for S in argyrodite-type sulfide-based solid electrolytes enhances the stability by suppressing reaction with H2O and decomposition. O substitution modulates the electronic structures and then improves electrochemical performance.

The poor reversibility of Zn metal anodes arising from water-induced parasitic reactions poses a significant challenge to the practical applications of aqueous zinc-ion batteries (AZIBs). Herein, a novel quasi-solid-state water-in-swelling-clay electrolyte (WiSCE) containing zinc sulfate and swelling clay bentonite (BT) is designed to enable highly reversible Zn metal anodes. AZIB full 2 cells based on the WiSCE exhibit excellent cyclic stability at various current densities, long shelf life, low self-discharge rate, and outstanding high-temperature adaptability. Particularly, the capacity of WiSCE-based AZIB full cells retains 90.47% after 200 cycles at 0.1 A/g, 96.64% after 2000 cycles at 1 A/g, and 88.29% after 5000 cycles at 3 A/g. Detailed density functional theory calculations show that strong hydrogen-bonds are formed between BT and water molecules in the WiSCE. Thus, water molecules are strongly confined by BT particularly within the interlayers, which significantly inhibits water-induced side reactions and thus greatly improves cyclic stability. Compared to the state-of-the-art water-in-salt electrolyte, the WiSCE can provide a significantly higher capacity at the full-cell level with a substantially reduced cost, which is promising for the design of next-generation high-performance AZIBs. This work provides a new direction for developing cost-competitive AZIBs as alternatives in grid-scale energy storage.

Arrays of electrical devices with each comprising multiple single-walled carbon nanotubes (SWNT) bridging metal electrodes are obtained by chemical vapor deposition (CVD) of nanotubes across prefabricated electrode arrays. The ensemble of nanotubes in such a device collectively exhibits large electrical conductance changes under electrostatic gating, owing to the high percentage of semiconducting nanotubes. This leads to the fabrication of large arrays of low-noise electrical nanotube sensors with 100% yield for detecting gas molecules. Polymer functionalization is used to impart high sensitivity and selectivity to the sensors. Polyethyleneimine coating affords n-type nanotube devices capable of detecting NO2 at less than 1 ppb (parts-per-billion) concentrations while being insensitive to NH3. Coating Nafion (a polymeric perfluorinated sulfonic acid ionomer) on nanotubes blocks NO2 and allows for selective sensing of NH3. Multiplex functionalization of a nanotube sensor array is carried out by microspotti...

High drive current is a critical performance parameter in semiconductor devices for high-speed, low-power logic applications or high-efficiency, high-power, high-speed radio frequency (RF) analog applications. In this work, we demonstrate an In2O3 transistor grown by atomic layer deposition (ALD) at back-end-of-line (BEOL) compatible temperatures with a record high drain current exceeding 10 A/mm, the performance of which is 2-3 times better than all known transistors with semiconductor channels. A record high transconductance of 4 S/mm is also achieved among all transistors with a planar structure. It is found that a high carrier density and high electron velocity both contribute to this remarkably high on-state performance in ALD In2O3 transistors, which is made possible by the high-quality oxide/oxide interface, the metal-like charge-neutrality-level (CNL) alignment, and the high band velocities induced by the low density-of-state (DOS). Experimental Hall, I-V and split C-V measurements at room temperature confirm a high carrier density up to 6-7*10^13 /cm2 and a high velocity of about 10^7 cm/s. Ultra-thin oxide semiconductors, with a CNL located deep inside the conduction band, represent a promising new direction for the search of alternative channel materials for high-performance semiconductor devices.

The advancement of ion transport applications will require the development of functional materials with a high ionic conductivity that is stable, scalable, and micro-patternable. We report unusually high ionic conductivity of Li+, Na+, and K+ in 2D MoS2 nanofilm exceeding 1 S/cm, which is more than 2 orders of magnitude higher when compared to that of conventional solid ionic materials. The high ion conductivity of different cations can be explained by the mitigated activation energy via percolative ion channels in 2H-MoS2, including the 1D ion channel at the grain boundary, as confirmed by modeling and analysis. We obtain field-effect modulation of ion transport with a high on/off ratio. The ion channel is large-scale patternable by conventional lithography, and the thickness can be tuned down to a single atomic layer. The findings yield insight into the ion transport mechanism of van der Waals solid materials and guide the development of future ionic devices owing to the facile and scalable device fabrication with superionic conductivity.

A quantitative study on inelastic electron scattering with a molecule is of significant importance for understanding the essential mechanisms of electron-induced gas-phase and surface chemical reactions in their excited electronic states. A key issue to be addressed is the quantitatively detailed inelastic electron collision processes with a realistic molecular target, associated with electron excitation that leads to potential ionization and dissociation reactions of the molecule. Using the real-time time-dependent density functional theory (TDDFT) modeling, we present quantitative findings on the energy transfers and internal excitations for the low energy (up to 270 eV) electron wave packet impact with the molecular target cobalt tricarbonyl nitrosyl (CTN, Co(CO)3NO) that is used as a precursor in electron-enhanced atomic layer deposition (EE-ALD) growth of Co films. Our modeling shows the quantitative dependence of the wave packet sizes, target molecule orientations, and impact parameters on the energy transfer in this inelastic electron scattering process. It is found that the wave packet sizes have little effect on the overall profile of the internal multiple excited states, whereas different target orientations can cause significantly different internal excited states. To evaluate the quantitative prediction capability, the inelastic scattering cross-section of a hydrogen atom is calculated and compared with the experimental data, leading to a constant scaling factor over the whole energy range. The present study demonstrates the remarkable potential of TDDFT for simulating the inelastic electron scattering process, which provides critical information for future exploration of electronic excitations in a wide range of electron-induced chemical reactions in current technological applications.

The excited state quantum dynamics of the organic cation in hybrid perovskites are investigated using the time-dependent density functional theory (TDDFT). The time-dependent non-adiabatic bond fluctuation behaviors reveal that the energy relaxation follows different pathways depending on the chemical bonding characteristics and energy transfer modes within the cation molecule, which can fundamentally affect its photostability. For the ammonium-group-containing cations, such as methylammonium (MA) or ethylammonium (EA), local vibrational modes survive for a long time. However, as their lowest unoccupied molecular orbital (LUMO) having π* characters, the amidinium-group-containing cations, such as formamidinium (FA) or guanidinium (GA), efficiently dissipate deposited energy via chaotic intramolecular vibrational energy redistribution (IVR). The distinct dynamic behaviors of A-site molecular cations are closely related to the quantum ergodicity, which can bring enhanced photochemical stability of FA and GA compared to MA and EA. Our theoretical investigation reveals the quantum chaos origin of better light stability of FA-based perovskites and serves the future research direction of the A-site engineering for better solar cells and light-emitting devices.

Graphite is currently utilized as anode materials for Li-ion batteries, but it is well-known that graphite does not show good electrochemical performances as the anode material for sodium-ion batteries (SIBs). It was also reported that the low electrochemical performances of graphite originated from the larger ionic radius of the sodium ion due to the required higher strain energy for sodium-ion intercalation into graphite leading to an unstable sodium-ion intercalated graphite intercalation compound (GIC). In this work, using first-principles calculations, we introduce pillaring effects of Na n X (n = 3 and 4; X = F, Cl, or Br) halide clusters in GICs, which become electrochemically active for Na redox reactions. Specifically, to enable sodium-ion intercalation into graphite, the interlayer spacing of graphite is required to increase over 3.9 A, and Na n X halide cluster GICs maintain an expanded interlayer spacing of >3.9 A. This enlarged interlayer spacing of Na n X halide cluster GICs facilitates stable intercalation of sodium ions. Na3F, Na4Cl, and Na4Br halide clusters are identified as suitable pillar candidates for anode materials because they not only expand the interlayer spacing but also provide reasonable binding energy for intercalated sodium ions for reversible deintercalation. Based on the model analysis, theoretical capacities of Na3F, Na4Cl, and Na4Br halide cluster GICs are estimated respectively to be 186, 155, and 155 mA h g-1. These predictions would provide a rational strategy guiding the search for promising anode materials for SIBs.

Pump it up Carbon nanotube yarns can be used as electrochemical actuators because infiltration with ions causes a contraction in length and an expansion in diameter. Either positive or negative ions can cause this effect. Chu et al. constructed an all-solid-state muscle that eliminated the need for an electrolyte bath, which may expand the potential for its use in applications. By infiltrating the yarns with charged polymers, the fibers start partially swollen, so the length can increase through the loss of ions. It is thus possible to increase the overall stroke of the muscle. Further, these composite materials show a surprising increase in stroke with scan rate. Science , this issue p. 494

In this study, we present improved power characteristics and suppressed phase transition by incorporating elemental doping into a P2-type cathode of sodium ion batteries. A Cu-doped Fe–Mn based P2-type Na0.67Cu0.125Fe0.375Mn0.5O2 cathode was designed based on the calculations of the electronic structure and then examined experimentally. Using first principles, we introduced instrinsic p-type conductivity by elemental doping with Cu. Introduction of Cu generated electron holes above the Fermi level in the electronic structure, which is typical of p-type semiconductors. Charge analyses suggested that the hole generation was driven primarily by the greater reduced characteristics of Cu as compared with those of Fe and Mn. In addition, introduction of Cu retaining high reduced property also suppressed phase transition from the P2 to Z phase by Fe migration to empty Na layers mainly. Electrochemical experiments revealed improved power characteristics upon the introduction of p-type conductivity. This could be attributed to the increase in the electronic conductivity by hole generation in the valence band. This study suggests that the introduction of p-type conductivity could be a rational tactic for the development of promising cathode materials for high performance sodium ion batteries.

Reducing sulfur poisoning is significant for maintaining the catalytic efficiency and durability of heterogeneous catalysts. We screened PdAu nanoclusters with specific Pd : Au ratios based on Monte Carlo simulations and then carried out density functional calculations to reveal how to reduce sulfur poisoning via alloying. Among various nanoclusters, the core-shell structure Pd13Au42 (Pd@Au) exhibits a low adsorption energy of SO2 (-0.67 eV), comparable with O2 (-0.45 eV) and lower than CO (-1.25 eV), thus avoiding sulfur poisoning during the CO catalytic oxidation. Fundamentally, the weak adsorption of SO2 originates from the negative d-band center of the shell and delocalized charge distribution near the Fermi level, due to the appropriate charge transfer from the core to shell. Core-shell nanoclusters with a different core (Ni, Cu, Ag, Pt) and a Pd@Au slab model were further constructed to validate and extend the results. These findings provide insights into designing core-shell catalysts to suppress sulfur poisoning while optimizing catalytic behaviors.

Fluorine doping of a compositionally graded cathode, with an average concentration of Li[Ni0.80Co0.05Mn0.15]O2, yields a high discharge capacity of 216 mA h g−1 with unprecedented cycling stability by retaining 78% of its initial capacity after 8000 cycles. The cathode is cycled at 100% depth of discharge (DOD), unlike the currently deployed layered cathode whose DOD is limited to 60–80% to compensate for capacity fading and guarantee the required battery life. Additionally, the capacity and cycling stability of the cathode easily surpass those of the existing state-of-the-art batteries, while achieving the energy density goal of 800 W h kg−1cathode for electric vehicles (EV) with ultra-long cycle life. The structural and chemical stabilities of the cathode were provided by the compositional partitioning and unique microstructure of the compositionally graded cathode combined with the ordered site-intermixing of Li and transition metal (TM) ions discovered via transmission electron microscopy. F doping induced the formation of a 2ahex × 2ahex × chex superlattice from ordered Li occupation in TM slabs and vice versa, which has been proven to be essential for suppressing microcrack formation in deeply charged states, while maintaining the structural stability of the cathode during extended cycling. Furthermore, the proposed cathode allows for the recycling of used EV batteries in energy storage systems, thereby alleviating the negative environmental impact by reducing the CO2 emissions and cost associated with disposing of dead batteries.

Density functional theory (DFT) is employed to investigate ferroelectric (FE) hafnium-zirconium oxide stack models for both metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) structures. The role of dielectric (DE) interlayers at the ferroelectric interfaces with metals and semiconductors and the effects of thickness scaling of FE and DE layers were investigated using atomic stack models. A high internal field is induced in the FE and DE layers by the FE polarization field which can promote defect generation leading to limited endurance. It is also shown that device operation will be adversely affected by too thick DE interlayers due to high operating voltage. These DFT models elucidate the underlying mechanisms of the lower endurance in experimental MIS devices compared to MIM devices and provide insights into the fundamental mechanisms at the interfaces.