Non-ideal Interface Research Articles

Enhancement of CO2/N2 separation in MMMs by the regulation of nanofiller microenvironment

Mixed-matrix membranes (MMMs) incorporating Metal-Organic Frameworks (MOFs) represent a promising approach for gas separation, which can combine the advantages of selective adsorbents and processable polymers, and display great potential in the gas separation process. However, the further application of MMMs is severely impeded owing to the non-ideal interface between fillers and polymer matrix. In this work, a series of MIL-101(Cr) nanofillers, equipped with different kinds of counter anions were introduced to regulate the chemical microenvironment of the MMMs and improve the interfacial relationship between inorganic filler and polymer. The filler of MIL-101-HNO3 exhibits improved dispersibility in solvents and heightened interface relationship with the polymer matrix (PIM-1) due to its optimal particle size and distinctive exposure of crystallographic planes. Moreover, gas sorption isotherms reveal that the MIL-101-HNO3 MOF show reduced N2 adsorption capacity. Therefore, the MOF filler of MMMs were optimized rationally by microenvironment regulate strategy, leading to the MIL-101-HNO3/PIM-1 MMMs achieve high CO2 permeability and exceptional CO2/N2 ideal selectivity (CO2 = 14879 barrer, CO2/N2 = 24.3), surpassing the latest 2019 upper bound. That makes MIL-101-HNO3/PIM-1 a potential candidate for the selective removal of CO2 from stack gas and provides new insights into the regulation of the MMMs nanofiller microenvironment.

About the quantum‐kinetic derivation of boundary conditions for quasiparticle Boltzmann equations at interfaces

AbstractQuite a many electron transport problems in condensed matter physics are analyzed with a quasiparticle Boltzmann equation. For sufficiently slowly varying weak external potentials it can be derived from the basic equations of quantum kinetics, provided quasiparticles can be defined and lead to a pole in the quantum‐mechanical propagators. The derivation breaks down, however, in the vicinity of an interface which constitutes an abrupt strong perturbation of the system. In this contribution we discuss in a tutorial manner a particular technique to systematically derive, for a planar, nonideal interface, matching conditions for the quasi‐particle Boltzmann equation. The technique is based on pseudizing the transport problem by two auxiliary interface‐free systems and matching Green functions at the interface. Provided quasiparticles exist in the auxiliary systems, the framework can be put onto the semiclassical level and the desired boundary conditions result. For ideal interfaces, the conditions can be guessed from flux conservation, but for complex interfaces this is no longer the case. The technique presented in this work is geared toward such interfaces.

Recent progress in SEI engineering for boosting Li metal anodes.

Lithium metal anodes (LMAs) are ideal anode candidates for achieving next-generation high-energy-density battery systems due to their high theoretical capacity (3680 mA h g-1) and low working potential (-3.04 V versus the standard hydrogen electrode). However, the non-ideal solid electrolyte interface (SEI) derived from electrolyte/electrode interfacial reactions plays a vital role in the lithium deposition/stripping process and battery cycling performance. The composition and morphology of a SEI, which is sensitive to the outside environment, make it difficult to characterize and understand. With the development of characterization techniques, the mechanism, composition, and structure of a SEI can be better understood. In this review, the mechanism formation, the structure model evolution, and the composition of a SEI are briefly presented. Moreover, the development of in situ characterization techniques in recent years is introduced to better understand a SEI followed by the properties of the SEI, which are beneficial to the battery performance. Furthermore, recent optimization strategies of the SEI including the improvement of intrinsic SEIs and construction of artificial SEIs are summarized. Finally, the current challenges and future perspectives of SEI research are summarized.

Construction of high-performance thin-film composite membrane for CO2 separation via interface engineering

High-efficiency CO2 capture has become increasingly vital for alleviating the ongoing global temperature which leads to severe impacts on virtually every aspect of human life. Thin-film composite membranes (TFCM) have attracted growing attention for conducting CO2 capture, owning to their energy-efficient and environment-friendly merits. However, the nonideal interface between the gutter layer and the separation layer hampers the fabrication of defect-free and thin separation layer, which renders low separation performance. In this work, we developed a strategy, i.e., coupling the oxygen-plasma modification with spin-coating, for engineering the interface between the gutter layer and separation layer of TFCM. Leveraging this idea, the TFC membrane, consisting polydimethylsiloxane (PDMS) served as the gutter layer and poly (ether-block-amide) (PEBA) as the thin separation layer, was manufactured by conveniently spin-coating PEBA solution on the oxygen-plasma-treated PDMS layer. The optimized PEBA-based TFCM membrane realized superior separation performance, e.g., a CO2 permeance of 2011 GPU, a CO2/N2 selectivity of 24, and 100-hour stably running, which outperformed most of the reported PEBA-based TFCM. Thus, the interface engineering strategy proposed in this study opens a new door for rational fabrication of high-performance TFCM.

Buried Interface Dielectric Layer Engineering for Highly Efficient and Stable Inverted Perovskite Solar Cells and Modules.

Stability and scalability are essential and urgent requirements for the commercialization of perovskite solar cells (PSCs), which are retarded by the non-ideal interface leading to non-radiative recombination and degradation. Extensive efforts are devoted to reducing the defects at the perovskite surface. However, the effects of the buried interface on the degradation and non-radiative recombination need to be further investigated. Herein, an omnibearing strategy to modify buried and top surfaces of perovskite film to reduce interfacial defects, by incorporating aluminum oxide (Al2 O3 ) as a dielectric layer and growth scaffolds (buried surface) and phenethylammonium bromide as a passivation layer (buried and top surfaces), is demonstrated. Consequently, the open-circuit voltage is extensively boosted from 1.02 to 1.14V with the incorporation of Al2 O3 filling the voids between grains, resulting in dense morphology of buried interface and reduced recombination centers. Finally, the impressive efficiencies of 23.1% (0.1 cm2 ) and 22.4% (1 cm2 ) are achieved with superior stability, which remain 96% (0.1 cm2 ) and 89% (1 cm2 ) of its initial performance after 1200 (0.1 cm2 ) and 2500h (1 cm2 ) illumination, respectively. The dual modification provides a universal method to reduce interfacial defects, revealing a promising prospect in developing high-performance PSCs and modules.

Correlation of interfacial stress with the surface roughness of carbon fiber in composites by the improved shear-lag theory

ABSTRACT An improved shear-lag model is proposed in this article to study the effects of interface roughness and interfacial stiffness on the mechanical properties of a representative volume element (RVE). The surface roughness of the fiber is represented by grooves distributed around the fiber. The interfacial stiffness is introduced by the cohesive zone modeling (CZM) to study the nonideal adhesion interface. This paper also considered the influence of fiber length on stress transfer. The theoretical model was validated through numerical simulation considering both regularly and irregularly distributed grooves. The results show that the improved shear-lag model can describe the interfacial stress properties accurately. Furthermore, it is found that the influence of surface roughness varies for different interfacial stiffness. The proposed method and results can guide the design and analysis of interfacial modifications in carbon fiber composites.

Propagation Characteristics of SH Wave in Orthotropic Layer/Piezoelectric Column Structure

The propagation characteristics of SH waves along the circumferential direction in an orthotropic layer/piezoelectric column structure with a non-ideal interface are studied in this paper. By solving the governing equations, the solutions to the problem are expressed by the first and second Bessel functions. The dispersion equation is obtained by the boundary conditions and the interface conditions. The numerical examples are provided to show the effects of the degree of orthogonal anisotropy, the thickness-diameter ratio, and the imperfect interface on the dispersion characteristics.

Ultraviolet Filtration Passivator for Stable High-Efficiency Perovskite Solar Cells.

Although the published values of power conversion efficiency (PCE) have increased continuously in recent years for perovskite solar cells (PSCs), improvements in the stability and performance of PSCs with conventional TiO2 or SnO2 electron transport layers (ETLs) remain limited by the presence of nonideal interface defects and low ultraviolet (UV) absorption. In this study, 2-hydroxy-4-methoxy-5-sulfonate-benzophenone (SBP), an inexpensive water-soluble sunscreen raw material, was incorporated into the SnO2 ETL as a UV filter. It was found that the exposure of perovskite to UV light was significantly reduced, and, more importantly, the carbonyl and sulfonic acid groups in the SBP influenced both the perovskite crystallization process and the passivation of defects in the ETL/perovskite film interface. As a result, the PCE of SBP-based devices was increased to 22.54% from 20.78% of the control sample, with a concomitant decrease in the hysteresis. Moreover, the efficiency of champion devices with SBP decreased by less than 5% after 200 h of continuous UV (1.63 mW/cm2, 285 nm) irradiation, while the control group dropped to below 75% of the initial value, thus showing significantly improved stability.

Over 15% efficient wide-band-gap Cu(In,Ga)S2 solar cell: Suppressing bulk and interface recombination through composition engineering

Over 15% efficient wide-band-gap Cu(In,Ga)S2 solar cell: Suppressing bulk and interface recombination through composition engineering

(Invited) Fundamentals and Process Technologies of Current Aperture Vertical Ga2O3 MOSFETs

Ga2O3 has exploded onto the semiconductor landscape for next-generation power electronics because its enticing material properties, most notably a large critical field strength stemming from its ultra-wide bandgap of 4.5 eV, promise miniaturized circuits and systems with high conversion efficiency. High-quality native substrates produced by melt-growth methods offer an economical platform to this technology. Ga2O3 transistors reported to date have predominantly taken on a lateral geometry, yet vertical switching devices are desirable for applications that demand high voltage ratings and high power levels since they allow for large current drives, simplified thermal management, and superior field termination. Capitalizing on cost-effective ion implantation technologies for shallow donor (silicon) and deep acceptor (nitrogen) doping of Ga2O3 with efficient dopant activation at a low thermal budget, we developed both depletion-mode (D-mode) [1] and enhancement-mode (E-mode) [2] current aperture vertical Ga2O3 metal-oxide-semiconductor field-effect transistors (MOSFETs).The vertical Ga2O3 MOSFETs were fabricated on low-doped (~1016 cm-3) halide vapor phase epitaxial drift layers grown on single-crystal β-Ga2O3 (001) substrates [3]. In these devices, silicon ion-implanted top source contacts were electrically isolated from the bottom drain contact by a nitrogen ion-implanted current blocking layer (CBL) [4] except at an aperture bounded by CBLs through which drain current was conducted. The CBL simultaneously served as a back-barrier for a top-gated lateral channel defined by another silicon ion implantation step. D-mode devices delivered a drain current density of 0.42 kA/cm2, a specific on-resistance of 31.5 mΩ·cm2, and an output current on/off ratio of over 108. E-mode devices, whose positive threshold voltage was attained by appropriately designing the channel doping concentration such that the channel was fully depleted at 0-V gate bias, showed a high output current on/off ratio of 2×107 despite a nonideal MOS interface that limited the maximum drain current density to <0.1 kA/cm2. Both D-mode and E-mode devices did not exhibit current collapse in pulsed measurements when subjected to off-state voltage stress; however, their hard breakdown occurred prematurely owing to leakage through the CBLs, a deficiency expected to be readily overcome with an optimized nitrogen implantation process. Further details regarding fabrication, performance, and physics of the devices, as well as potential directions for future development, will be discussed in the talk. The demonstration of planar-gate vertical Ga2O3 transistors based on a highly manufacturable all-ion-implanted process greatly enhances the prospects for Ga2O3-based power electronics applications.[1] M. H. Wong, K. Goto, H. Murakami, Y. Kumagai, and M. Higashiwaki, IEEE Electron Device Lett. 40, 431 (2019).[2] M. H. Wong, H. Murakami, Y. Kumagai, and M. Higashiwaki, Proc. 77th Device Research Conference (2019).[3] H. Murakami, K. Nomura, K. Goto, K. Sasaki, K. Kawara, Q. T. Thieu, R. Togashi, Y. Kumagai, M. Higashiwaki, A. Kuramata, S. Yamakoshi, B. Monemar, and A. Koukitu, Appl. Phys. Express 8, 015503 (2015).[4] M. H. Wong, C.-H. Lin, A. Kuramata, S. Yamakoshi, H. Murakami, Y. Kumagai, and M. Higashiwaki, Appl. Phys. Lett. 113, 102103 (2018).

Enhancement-Mode $\beta$ -Ga2O3 Current Aperture Vertical MOSFETs With N-Ion-Implanted Blocker

Enhancement-mode (E-mode) vertical $\beta $ -Ga2O3 metal–oxide–semiconductor (MOS) field-effect transistors featuring a current aperture were developed on a single-crystal $\beta $ -Ga2O3 (001) substrate. Nitrogen ions were implanted into a drift layer grown by halide vapor phase epitaxy to form current blocking layers (CBLs) for vertical source–drain isolation, while Si ions were implanted to form degenerately doped source contact regions and a top-gated lateral channel that was fully depleted at 0-V gate bias. The devices delivered a high output current on/off ratio of $2\times {10}^{{7}}$ despite a nonideal MOS interface that limited the maximum drain current density to <0.1 kA/cm2. Pulsed operation without current collapse under off-state voltage stress was demonstrated. Hard breakdown occurred prematurely owing to leakage through the CBLs, but is expected to improve with an optimized nitrogen implantation process. The realization of E-mode vertical Ga2O3 transistors based on a manufacturable all-ion-implanted process represents an important step toward practical applications of Ga2O3 power electronics.

半空间中具有非理想界面的圆柱形芯–壳结构对P波的多重衍射

半空间中具有非理想界面的圆柱形芯–壳结构对P波的多重衍射

Improving the charge separation and collection at the buffer/absorber interface by double-layered Mn-substituted CZTS

A non-ideal buffer-absorber interface due to interface recombination is one of the limitations in Cu2ZnSnS4 (CZTS) solar cells. An absorber gradient using partial cation-substitution is one possible solution to this issue by reducing interface recombination sites and improving band alignment. Partial substitution of Zn with Mn is a potentially attractive concept owing to its abundance as well as similar size and electronic properties compared to Zn. In this study, Cu2MnxZn1-xSnS4 (CMZTS) thin film were fabricated by a sol-gel spin coating technique to understand the effect of Mn on the device performance. X-ray diffraction (XRD) and Raman analysis confirm Mn substitution for Zn in the crystal lattice of Cu2ZnSnS4 (CZTS) with no secondary phases detected for x ≤ 0.4. Enhancement of short circuit current (Jsc) in Cu2Mn0.15Zn0.85SnS4 has led to improved efficiency in comparison with CZTS. Since external quantum efficiency (EQE) indicates the short wavelength collection as the main reason for the improved Jsc, we designed a double layered structure of CZTS as bottom layer and CM0.15Z0.85TS as top layer. With this structure, we obtained our best performance cell with power conversion efficiency (PCE) of 5.73% and Jsc of 17.86 mA/cm2. The improved Jsc is attributed to increased depletion width and higher activation energy of the limiting recombination mechanism as shown by capacitance-voltage and temperature dependent current-voltage measurements. Our study concludes that CM0.15Z0.85TS top layer improves the interface quality of the p-n junction and may be an alternative method to improve the performance of CZTS solar cells.

Electron beam induced strong organic/inorganic grafting for thermally stable lithium-ion battery separators

A tailored interface between organic and inorganic materials is of great importance to maximize the synergistic effects from hybridization. Polyethylene separators over-coated with inorganic thin films are the state-of-the art technology for preparing various secondary batteries with high safety. Unfortunately, the organic/inorganic hybrid separators have the drawback of a non-ideal interface, thus causing poor thermal/dimensional stability. Here, we report a straightforward method to resolve the drawback of the non-ideal interface between vapor deposited SiO2 and polyethylene separators, to produce a highly stable lithium-ion battery separator through strong chemical linking generated by direct electron beam irradiation. The simple treatment with an electron beam with an optimized dose generates thermally stable polymer separators, which may enhance battery safety under high-temperature conditions. Additionally, the newly formed Si–O–C or Si–CH3 chemical bonding enhances electrolyte-separator compatibility and thus may provide a better environment for ionic transport between the cathode and anode, thereby leading to better charge/discharge behaviors.

Structures with bridged cracks and weak interfaces

Structures with interfacial bridged cracks and weak interfaces are analyzed. In the frames of this approach is assumed that: a) the crack surfaces interact in some zones behind the crack tips (bridged zones); b) size of these zones can be comparable to the whole crack length; and c) the interface between different materials can be connected by mechanical ligaments and a relative displacement of initially adjacent materials may occur (non-ideal or weak interface). Several new problems for interface bridged cracks and interaction of bridged cracks with material interface were solved and analyzed by the direct boundary integral equations method.

BECN2 interacts with ATG14 through a metastable coiled-coil to mediate autophagy.

ATG14 binding to BECN/Beclin homologs is essential for autophagy, a critical catabolic homeostasis pathway. Here, we show that the α-helical, coiled-coil domain (CCD) of BECN2, a recently identified mammalian BECN1 paralog, forms an antiparallel, curved homodimer with seven pairs of nonideal packing interactions, while the BECN2 CCD and ATG14 CCD form a parallel, curved heterodimer stabilized by multiple, conserved polar interactions. Compared to BECN1, the BECN2 CCD forms a weaker homodimer, but binds more tightly to the ATG14 CCD. Mutation of nonideal BECN2 interface residues to more ideal pairs improves homodimer self-association and thermal stability. Unlike BECN1, all BECN2 CCD mutants bind ATG14, although more weakly than wild type. Thus, polar BECN2 CCD interface residues result in a metastable homodimer, facilitating dissociation, but enable better interactions with polar ATG14 residues stabilizing the BECN2:ATG14 heterodimer. These structure-based mechanistic differences in BECN1 and BECN2 homodimerization and heterodimerization likely dictate competitive ATG14 recruitment.

Reducing Peak Pressures Under the Saddle Panel at the Level of the 10th to 13th Thoracic Vertebrae May Be Associated With Improved Gait Features, Even When Saddles Are Fitted to Published Guidelines

Saddle–horse interaction is increasingly linked with back pain, performance, and welfare issues. Saddle fit and work quality influence alterations in back shape with exercise at thoracic vertebra 13 level (T13) with exercise. The objectives of experiments were to: determine a repeatable zone and stride point of peak pressure under saddles fitted to industry guidelines; compare peak pressure in this zone and limb kinematics in collected trot between horses own saddles (S) and a saddle designed to reduce pressure at T10–T13 (F); compare thoracolumbar width change after exercise between S and F and with F after 3 months use. Elite dressage (n = 13) horses/riders with no lameness/performance problem had pressure mat data acquired under S, fitted by four qualified saddle fitters, to determine zones of peak pressure. Pressure mat data at T10–T13, forelimb/hindlimb protraction, and carpal/tarsal flexion acquired using simultaneous high-speed motion capture, and difference in thoracolumbar dimensions (T8, T18 at 3, 15 cm) between before and after exercise was compared between S and F. Peak pressures were consistently detected axially around T10–T13 (sensors A4–A7, H4–H7). Peak pressures were significantly less with F than S for each cell and pooled (55%–68% difference. P = .01 to <.0001). Saddle F was associated with 13% greater forelimb and 22.7% hindlimb protraction, 3.5° greater carpal and 4.3° tarsal flexion (P = .02 to .0001), and greater increase in thoracolumbar dimensions after exercise (P = .01 to <.0001). Saddles fitted to published guidelines may still have a nonideal interface with horses. Reducing peak pressures around T10–T13 was associated with improved limb kinematics in trot and greater thoracolumbar expansion after exercise.

Resonant Magnetoelectric Effect in Winglike Magnetoelectric Composites of Fe-Based Nanocrystalline FeCuNbSiB Alloy and Piezoelectric Ceramic Pb(Zr,Ti)O&lt;sub&gt;3&lt;/sub&gt; With Middle Bonding

Magnetoelectric (ME) composites consisting of piezoelectric materials and magnetostrictive materials have been studied extensively due to their large ME effects than those in single phases [1-2], offering promise for magnetic moment sensing and other applications. In these composites, the ME coefcient is dependent upon the elastic coupling that occurs at the interface between piezoelectric and magnetostrictive phases. Therefore, the interfacial coupling is a key factor that determines the ME response of layered composites. In fact, there is no ideal interfacial coupling for the classical strain mediated ME laminated composites, because they are usually constructed layer by layer through interface bonding with epoxy adhesive. This kind of non-ideal interface bonding can dampen the generated strain and mechanical quality factor, cause frequency shift, and also contribute to the noise oor and aging [3]. Recently, some studies have attempted to achieve ME responses, which are not inuenced by interfacial conditions. A stretching mechanically mediated structure of TbFe 2 / PZT/TbFe 2 with two nonmagnetic akes is designed to achieve the ME coupling by end bonding instead of interface bonding [4]. A ME heterostructure made by attaching magnetostrictive Metglas at the free ends of a PZT plate exhibits large ME response [5]. However, there are still too much interfacial contact exist, at least two end contacts. The influence of interfacial contact can be further decreased by new structure.

On the diameter dependence of metal-nanowire Schottky barrier height

Bardeen's model for the non-ideal metal-semiconductor interface was applied to metal-wrapped cylindrical nanowire systems of 30–400 nm in diameter; a significant effect of the nanowire diameter on the non-ideal Schottky barrier height was found. The calculations were performed by solving Poisson's equation in the nanowire, self-consistently with the constraints set by the non-ideal interface conditions; in these calculations, the barrier height is obtained from the solution, and it is not a boundary condition for Poisson's equation. The main finding is that thin nanowires are expected to have O(10−100) meV higher Schottky barriers compared to their thicker counterparts; an effect 3–4 times stronger than the diameter dependence of image-force barrier lowering in similar systems. What lies behind this effect is the electrostatic properties of metal-wrapped nanowires; in particular, since depletion charge is reduced with nanowire radius, the potential drop on the interfacial layer is reduced—leading to the increase of the barrier height with nanowire radius reduction.

ZIF-8/PDMS mixed matrix membranes for propane/nitrogen mixture separation: Experimental result and permeation model validation

In this contribution, zeolitic imidazolate framework (ZIF-8)/polydimethylsiloxane (PDMS) mixed matrix membranes (MMMs) were prepared for hydrocarbon recovery using propane/nitrogen mixture as a model feed gas pair. All MMMs obtained a homogeneous particle dispersion and intimate interface interaction, which were confirmed by high resolution scanning electric microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) mapping. Gas permeation test shows that ZIF-8/PDMS MMMs demonstrate an enhanced separation performance with improved separation selectivity (38% higher than that of pure PDMS membranes) and propane permeance over 100GPU. However, it is worth noting that the enhanced selectivity and decreased permeance of MMMs contradict the prediction by Maxwell model, which suggests the existence of pore blockage and inhibited chain mobility at polymer-particle interface. The inhibited chain mobility is further confirmed by differential scanning calorimetry (DSC) analysis. Based on these observations, a new modified Maxwell model is proposed taking non-ideal interface morphology and particle agglomeration into consideration. Both the selectivity and gas permeance predicted by the proposed model are in good agreement with experimental data, which thereby extends the application scope of original Maxwell model.