Layer Thickness Research Articles

Combining graph deep learning and London dispersion interatomic potentials: A case study on pnictogen chalcohalides.

Machine-learning interatomic potential models based on graph neural network architectures have the potential to make atomistic materials modeling widely accessible due to their computational efficiency, scalability, and broad applicability. The training datasets for many such models are derived from density-functional theory calculations, typically using a semilocal exchange-correlation functional. As a result, long-range interactions such as London dispersion are often missing in these models. We investigate whether this missing component can be addressed by combining a graph deep learning potential with semiempirical dispersion models. We assess this combination by deriving the equations of state for layered pnictogen chalcohalides BiTeBr and BiTeI and performing crystal structure optimizations for a broader set of V-VI-VII compounds with various stoichiometries, many of which possess van der Waals gaps. We characterize the optimized crystal structures by calculating their x-ray diffraction patterns and radial distribution function histograms, which are also used to compute Earth mover's distances to quantify the dissimilarity between the optimized and corresponding experimental structures. We find that dispersion-corrected graph deep learning potentials generally (though not universally) provide a more realistic description of these compounds due to the inclusion of van der Waals attractions. In particular, their use results in systematic improvements in predicting not only the van der Waals gap but also the layer thickness in layered V-VI-VII compounds. Our results demonstrate that the combined potentials studied here, derived from a straightforward approach that neither requires fine-tuning the training nor refitting the potential parameters, can significantly improve the description of layered polar crystals.

Double Gold/Nitrogen Nanosecond-Laser-Doping of Gold-Coated Silicon Wafer Surfaces in Liquid Nitrogen

A novel double-impurity doping process for silicon (Si) surfaces was developed, utilizing nanosecond-laser melting of an 11 nm thick gold (Au) top film and a Si wafer substrate in a laser plasma-activated liquid nitrogen (LN) environment. Scanning electron microscopy revealed a fluence- and exposure-independent surface micro-spike topography, while energy-dispersive X-ray spectroscopy identified minor Au (~0.05 at. %) and major N (~1–2 at. %) dopants localized within a 0.5 μm thick surface layer and the slight surface post-oxidation of the micro-relief (oxygen (O), ~1.5–2.5 at. %). X-ray photoelectron spectroscopy was used to identify the bound surface (SiNx) and bulk doping chemical states of the introduced nitrogen (~10 at. %) and the metallic (<0.01 at. %) and cluster (<0.1 at. %) forms of the gold dopant, and it was used to evaluate their depth distributions, which were strongly affected by the competition between gold dopants due to their marginal local concentrations and the other more abundant dopants (N, O). In this study, 532 nm Raman microspectroscopy indicated a slight reduction in the crystalline order revealed in the second-order Si phonon band; the tensile stresses or nanoscale dimensions of the resolidified Si nano-crystallites envisioned by the main Si optical–phonon peak; a negligible a-Si abundance; and a low-wavenumber peak of the Si3N4 structure. In contrast, Fourier transform infrared (FT-IR) reflectance and transmittance studies exhibited only broad structureless absorption bands in the range of 600–5500 cm−1 related to dopant absorption and light trapping in the surface micro-relief. The room-temperature electrical characteristics of the laser double-doped Si layer—a high carrier mobility of 1050 cm2/Vs and background carrier sheet concentration of ~2 × 1010 cm−2 (bulk concentration ~1014–1015 cm−3)—are superior to previously reported parameters of similar nitrogen-implanted/annealed Si samples. This novel facile double-element laser-doping procedure paves the way to local maskless on-demand introductions of multiple intra-gap intermediate donor and acceptor bands in Si, providing related multi-wavelength IR photoconductivity for optoelectronic applications.

The Effect of Ellipsoidal Particle Surface Roughness on Drag and Heat Transfer Coefficients Using Particle-Resolved Direct Numerical Simulation

The purpose of this study is to estimate the effect of roughness layer thickness on the heat transfer and drag coefficients of ellipsoidal particles. Using an OpenFOAM-based particle-resolved direct numerical simulation (PR-DNS) method, we calculated the drag coefficient and Nusselt number for an isolated axisymmetric nonspherical particle with a rough surface in a uniform flow. The PR-DNS results indicate that the drag coefficient varies linearly with the effective roughness Sef at different angles, which can be expressed as CD=kSef−1+CD0. The changes in k are consistent with the Happel and Brenner equation. Furthermore, the influence of roughness on the heat transfer efficiency factor can be represented by Ef=Sef−65. The models for the drag coefficient and Nusselt number are valid within the ranges 1.25≤Ar≤2.5,1≤Sef≤2, and 10≤Rep≤200, thereby extending the applicability of the equations developed for smooth particles. These newly developed correlations for the drag coefficient and Nusselt number can be utilized for non-isothermal flows of particle mixtures containing materials with various rough-surfaced ellipsoids.

SCAPS numerical modeling of CBTS/WO3 thin film solar cell

The quaternary compound Cu2BaSnS4 (CBTS) has emerged as a suitable and attractive light-harvesting material due to its promising optoelectronic features as well as nontoxic and low-cost constituent elements. Yet efficiency of CBTS-based solar cells did not reach the Shockley-Queisser limit. Here, what we believe to be a novel structure ITO/WO3/CBTS heterojunction solar cell is designed and modeled using a solar cell capacitance simulator in one-dimension (SCAPS-1D). In this work, a what we also believe to be a novel WO3 as a buffer layer is proposed for the first time for the efficiency enhancement of CBTS thin film solar cells. Numerical investigation of the performance of CBTS-based solar cells without and with cuprous oxide (Cu2O) back surface field (BSF) is explored. The impact of thickness, doping density, bulk, and interface defect density of an absorber, buffer and window layer, working temperature, shunt and series resistance, back contact work function, and back surface recombination velocity were analyzed and optimized without and with the BSF layer. In this work, the optimized solar cell achieved an efficiency of 18.8%, fill factor (FF) of 83.79%, short-circuit current density (JSC) of 15.99 mA/cm2, and open circuit voltage (VOC) of 1.4 V without Cu2O BSF layer at optimal CBTS absorber and WO3 buffer layer thickness of 2 µm and 0.04 µm respectively. Furthermore, the efficiency boosted to 21.12% with VOC of 1.43 V, JSC of 16.8 mA/cm2 and FF of 87.77% by inserting 0.1 µm Cu2O BSF layer. Therefore, these results will facilitate the fabrication of an efficient and low-cost CBTS-based solar cell with promising WO3 and Cu2O as buffer and BSF layer, respectively.

Fluorinated Polymeric Multilayers by Off‐Stoichiometric Thiol‐Ene Photopolymerization

AbstractThis article reports the synthesis of a novel perfluoropolyalkylether (PFPAE) vinylether monomer and its use as a comonomer in the thiol‐ene photopolymerization of a trifunctional thiol together with a trifunctional vinylether. The crosslinked copolymers are obtained in the form of few mm thick layers and characterized. By changing the thiol/ene ratio, the polymers are optimized to tailor their surface composition and obtain adhesion between two thick layers despite the presence of the fluorinated monomer. The final bilayered structures are adhesive, and appeared chemically resistant, with good dimensional stability: therefore, these fluorinated thiol–ene based copolymers are likely to be of interest for applications based on layer‐by‐layer processes, such as additive manufacturing and microfluidics.

Experimental investigation and optimization of process parameters on tensile strength of carbon coated PLA material

Abstract This study explores the effect of key process parameters on the tensile strength of carbon-coated PLA (Polylactic Acid) material using additive manufacturing. The problem addressed is the need to enhance the mechanical properties of PLA, a widely used biodegradable polymer, by optimizing process parameters to improve its tensile strength when coated with carbon. The parameters investigated include infill pattern, printing speed, layer thickness, and orientation. A response surface methodology (RSM) was employed to design the experiments, while Minitab 15 software was used to analyze the data through analysis of variance (ANOVA). The results indicate that the optimal process parameters, linear infill pattern, printing speed of 20 mm/s, layer thickness of 150 µm, and Y-90 orientation, yield an average tensile strength of 56.4 MPa. A regression model was developed to predict tensile strength, with a high degree of accuracy (R² = 0.97). Confirmation tests verified the model’s predictions, contributing to the development of high-performance PLA-based materials for demanding applications.

Accuracy, Marginal, and Internal Fit of Additively Manufactured Provisional Restorations and Prostheses Printed at Different Orientations.

This systematic review aimed to assess the impact of printing orientation on the accuracy and properties of additively manufactured provisional restorations. A systematic literature search databases (PubMed, Scopus, Web of Science, and Cochrane) were conducted in July 2024 without language restrictions. The included studies were evaluated using the modified CONSORT checklist, and the effect measures and synthetic methods were employed to assess the accuracy of resin provisional restorations printed at various orientations. The web search resulted in 8228 records, and 15 records were ultimately included in the analysis. The printing orientation of provisional restorations has an impact on various factors such as the internal and marginal gap, trueness, precision, and accuracy. To achieve optimal results, it is recommended to utilize printing orientations of 180°, 150°, and 210°, as they showed lower marginal and internal gaps and higher accuracy. Caution should be exercised during the virtual positioning of supporting pillars, as this may also influence the overall accuracy. Horizontally and slightly tilted orientations have demonstrated superior accuracy. To achieve optimal results, factors such as printing layer thickness, printing technology, materials, and supportive pillars should be taken into consideration, besides the printing orientations. The selection of the optimum printing parameters overall printing orientations, layer thickness, and supportive pillar position can generate prosthetic and restorative dental parts with a long survival rate, saving time and effort by avoiding fracture, loss of retention, and consequent clinical complications.

A Study of Fit and Friction Force as a Function of the Printing Process for FFF 3D-Printed Piston–Cylinder Assembly

Current 3D printing processes for polymer material extrusion are limited in their accuracy in terms of dimension, form, and position. For precise results, post-processing is recommended, like with assembled parts such as pistons and cylinders wherein axial mobility is desired with low friction force and limited radial play. When no post-processing step of the printed parts is accomplished, the fit and the friction force behavior are strongly dependent on the process performances. This paper presents a study on parameters of significance and their effects on sliding and running fits as well as their friction forces for fused filament fabrication of such assemblies. A series of experiments were performed with multiple factors and levels, including the position or layout of printed objects, their layer thickness, the material used, the use of aligned or random seam, and the printer type. Piston–cylinder pairs were printed, measured, assembled, and tested using a tensile test frame. A mathematical model was developed to describe the oscillating friction force behavior observed. This study presents the feasibility and limitations of producing piston–cylinder assemblies with reduced play and friction when using appropriate conditions. It also provides recommendations to obtain and better control a desired running and sliding fit.

Intercomparison of Indexable Cutting Inserts’ Wear Progress and Chip Formation During Machining Hardened Steel AISI 4337 and Austenitic Stainless Steel AISI 316 L

This article deals with a mutual comparison of indexable cutting inserts of the CNMG 120408 type from two different manufacturers during the machining of hardened steel AISI 4337 and austenitic stainless steel AISI 316 L. The main goal is to analyse the different wear processes depending on the difference in the manufacturer’s design and also depending on the properties of the different machined materials. The progress of the wear of the main spine of the tool, the types of wear and the service life of the cutting edge were monitored, with the achievement of the critical value VBmax = 300 µm being the standard. In addition to the wear of the inserts, the production of chips was monitored in terms of their shape, average size and number of chips per 100 g of chips produced. In order to understand the relationships arising from the obtained data, an SEM equipped with an elemental analyser was used to analyse the coating layers and the substrate of the unworn inserts and the types of wear and the intensity of the surface damage of the worn inserts. A several-fold difference in the lifetime of the cutting edge was found, both in terms of design and in terms of the selected machined material, while in both cases the cutting edge with Al2O3 and TiCN layers of half thickness achieved a better result in liveness. From the point of view of chip formation, very similar results in shape and average length were observed despite the different designs of chip breakers. Cutting inserts with half the thickness of the coating layers achieved longer cutting edge life in the non-primary material application compared to the target workpiece material. At the same time, it was observed that a thinner coating layer has a positive effect on chip formation in terms of its length and shape.

A small disc size, a big challenge: effect of optic disc size on the correlation between peripapillary choroidal thickness, peripapillary retinal nerve fiber layer, and ganglion cell layer.

We aimed to analyze the effect of optic disc size on the correlation between the peripapillary choroid (PPC), peripapillary retinal nerve fiber layer (RNFL), and macular ganglion cell inner plexiform layer (MGCIPL) thicknesses in subjects with ocular hypertension (OHT) and primary open angle glaucoma (POAG). This study included 61 eyes with a disc area (DA) of ≤ 1.63 mm2, 92 eyes with a DA of 1.63-2.42 mm2, and 59 eyes with a DA of ≥ 2.42 mm2 in small disc, regular disc, and large disc groups, respectively. The swept-source optical coherence tomography scans of the PPC, RNFL, and MGCIPL were analyzed according to disc size. The three groups did not significantly differ in RNFL or MGCIPL measurements, but the PPC measurement was statistically significantly higher in the small disc group and statistically significantly thinner in the large disc group. Most of the correlations observed between the RNFL and MGCIPL measurements and eye characteristics in the regular disc group were not detected in the small and large disc groups. While the RNFL and MGCIPL were well correlated in all disc size groups, the PPC did not correlate with the RNFL or MGCIPL in any of the groups. Overall, the RNFL and MGCIPL measurements were consistent across all three disc sizes. While the PPC was thicker in small discs than in larger discs, it was not correlated with the RNFL or MGCIPL.

Role of submerged friction stir welding in reducing intermetallic growth and enhancing microstructure in dissimilar Al-Ti joints.

The integrity of dissimilar Al-Ti welds during conventional friction stir welding (CFSW) is compromised by excessive material mixing, leading to thick intermetallic layers. Underwater friction stir welding (UWFSW) mitigates these effects by inhibiting material mixing due to lower thermal conditions. Scanning electron microscopy revealed substantial Ti particles, appearing as blocks and strips, within the stir zone during CFSW. Static recrystallization, driven by exothermic reactions between Ti blocks and the Al matrix, resulted in over 93% recrystallized grains along stir zone, 10.7% higher than in UWFSW. In contrast, UWFSW resulted in a finer dispersion of Ti particles with reduced density due to lower frictional heat. The average grain size at the Ti interface of CFSW was 1.0μm, compared to 2.6μm in UWFSW. The inhomogeneous distribution of Ti particles in CFSW led to uneven dislocation distribution and increased stress concentrations, while finer Ti particles in UWFSW promoted a uniform grain structure, enhancing joint strength to 267MPa, 13.4% higher than CFSW. Additionally, the γ-fibre and basal fibre texture in UWFSW increased joint ductility. The study highlights UWFSW's effectiveness in joining dissimilar metals, offering significant advantages for industries such as aerospace and automotive.

Investigation of Hf/Ti bilayers for the development of transition-edge sensor microcalorimeters

The superconducting properties of 85 nm thick hafnium thin films with a 5 nm thick titanium layer on top have been investigated for three different geometries, that is, a film covering the entire 7 × 7 mm2 chip surface, bridges with a width of 200 μm and length up to 1800 μm, and bridges in the form of squares with sides from 100 to 1000 μm. The bridges were formed by a photolithographic lift-off process and are intended to be used as the main sensing element of a microcalorimeter based on a transition-edge sensor (TES) in experiments to determine the magnetic moment of neutrinos. Based on the measurements of the critical current, the critical temperature, and the width of the superconducting transition, we estimate the energy resolution δE of the TES prototypes, showing that it is possible to fabricate microcalorimeters with δE less than 1 eV using these films.

The role of erythropoietin in the treatment of ocular disorders: A literature review

Erythropoietin (EPO), traditionally known for its role in hematopoiesis, has garnered increasing attention for its neuroprotective properties, particularly in ocular disorders. This literature review explores the diverse roles of EPO in ocular health and its potential therapeutic applications. EPO’s involvement in ocular organogenesis and maintenance is highlighted, with evidence suggesting its correlation with gestational age and expression alongside crucial regulatory genes during eye development. Pre-clinical studies demonstrate EPO’s efficacy in preserving retinal integrity and mitigating neuronal damage in animal models of glaucoma, methanol optic neuropathy, and optic neuritis. Clinical investigations further support these findings, showing improvements in visual acuity and retinal nerve fiber layer thickness in patients treated with EPO. However, challenges such as optimizing dosage regimens and determining the most effective route of administration remain. Despite these challenges, EPO presents a promising avenue for vision preservation and the management of ocular disorders. Further research, including large-scale clinical trials and mechanistic studies, is warranted to solidify EPO’s role as a safe and effective therapeutic option in ocular diseases.

Effects of moringa polysaccharides on growth performance, immune function, rumen morphology, and microbial community structure in early-weaned goat kids

The aim of this research was to investigate the effects of adding moringa polysaccharides (MOP) on the growth performance, immune function, rumen tissue morphology, and rumen microbial community in early-weaned goat kids. Twenty-one 7-day-old Leizhou male goat kids weighing (3.05 ± 0.63) kg, were randomly divided into a control group (CON group), a low-dose group (LOW group), and a high-dose group (HIG group). MOP was added to the goat kids’ milk replacer (MR) at 0, 0.15, and 0.3% (on dry matter basis),fed until 60 days of age, and four goat kids in each group with body weights close to the mean of each group were selected for slaughter. The results showed that, compared to the CON group, the MOP groups significantly improved final body weight, body measurements, daily weight gain, and feed intake of the early weaned goat kids; significantly reduced the content of propionic acid, butyric acid, valeric acid, and ammoniacal nitrogen; and in addition, the addition of MOP could significantly increase the height of rumen nipple, the content of immunoglobulin G (IgG) in the serum. The HIG group significantly increased rumen pH, rumen muscularis layer thickness, rumen wall thickness, and serum immunoglobulin A (IgA), and immunoglobulin M (IgM). In conclusion, the addition of MOP positively impacted the growth performance, serum immune function, and rumen tissue morphology in early-weaned goat kids.

The Interfacial Reaction Traits of (Al63Cu25Fe12) 99Ce1 Quasicrystal-Enhanced Aluminum Matrix Composites Produced by Means of Hot Pressing

This study fabricated (Al63Cu25Fe12)99Ce1 quasicrystal-enhanced aluminum matrix composites using the hot-pressing method to investigate their interfacial reaction traits. Microstructure analysis revealed that at 490 °C for 30 min of hot-pressing, the interface between the matrix and reinforcement was clear and intact. Chemical diffusion between the I-phase and aluminum matrix during sintering led to the formation of Al7Cu2Fe, AlFe, and AlCu phases, which, with their uniform and fine distribution, significantly enhanced the alloy’s overall properties. Regarding compactness, it first increased and then decreased with different holding times, reaching a maximum of about 98.89% at 490 °C for 30 min. Mechanical property analysis showed that compressive strength initially rose and then fell with increasing sintering temperature. After 30 min at 490 °C, the reinforcement particles and matrix were tightly combined and evenly distributed, with a maximum compressive strength of around 790 MPa. Additionally, the diffusion dynamics of the transition layer were simulated. The reaction rate of the reaction layer increased with hot-pressing temperature and decreased with holding time. Selecting a lower temperature and appropriate holding time can control the reaction layer thickness to obtain composites with excellent properties. This research innovatively contributes to the preparation and property study of such composites, providing a basis for their further application.

Diffusion kinetics of borided of low entropy soft magnetic FeCo alloy

Abstract The growth kinetics of boride layers were investigated by boronizing the FeCo low entropy alloy produced by arc melting reverse vacuum system with the pack boriding method at temperatures of 1173 K, 1223 K, 1273 K and for 2, 4, 6 h. FeCo alloy has a single-phase FCC crystal structure and there are linear cracks and homogeneously distributed point voids in its microstructure. The hardness of FeCo alloy is between 170 HV0.05 and 265 HV0.05. The boride layer appearance has a sawtooth appearance, and the layer thickness varies between 62 µm and 172 µm depending on temperature and time. According to the XRD pattern, (CoFe)B and (CoFe)B2 triple phases are present on the boride layer surface. With pack boriding, the hardness of the boride layer increased up to 2262 HV0.05, and the surface hardness of the alloy improved by 8–10 times. The boride layer activation energy of the FeCo alloy boronized with pack boriding was calculated as 89.065 kJ mol−1.

A model of the earthquake cycle along the Gofar oceanic transform faults

The Gofar oceanic transform fault at the East Pacific Rise has one of the best seismic cycles recorded by modern instruments. The timing, location, and magnitude of major earthquakes (Mw>5.5) have been well constrained by data from global seismic networks for the past 30 years. The earthquake interval is short, about 3-5 years. Several segments have already experienced 5 cycles since 1995, when the seismic network was good enough for surface wave relocation. Two ocean bottom seismometer deployments (2008-2009, 2021-2023) also provide constraints on the seismic properties on the fault. This makes Gofar an ideal place to study earthquake cycles. Here, we developed a model for the seismic cycle along the Gofar transform fault using a semi-analytical approach for rapidly calculating 3D time-dependent deformation and stress caused by screw dislocations embedded within an elastic layer overlying a Maxwell viscoelastic half-space. The 160-km long fault is divided into three major segments with six asperities. Our model simulates the earthquake pattern on this fault for the past 30 years. Most of the time, each asperity ruptured as a large earthquake every 3-5 years. Most segments have a nearly constant Coulomb stress threshold of 2-3 MPa, providing optimal conditions for the forecasting of future earthquakes along Gofar. For three cases that deviated from this simple regular pattern, a large earthquake occurred with a centroid location between two asperities. This is likely due to concurrent rupture that involved both asperities. We also modeled surface deformation with different elastic layer thicknesses and mantle viscosities. Even though most deformation is in the horizontal direction, the difference in both horizontal and vertical directions between models can be as large as a few centimeters per year. Several seafloor geodesy methods can be used to differentiate between models, and seafloor pressure might be the most appropriate one at this remote location.

Enhanced Electromagnetic Wave Absorption in Hexaferrite/LSMO Bilayers: Optimization of Structural Design Using a High Frequency Software Simulation

In this study, the electromagnetic (EM) wave absorption properties of a two-layered structure composed of La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>-epoxy (10 wt.%) (LSMO) and SrFe<sub>9.5</sub>Co<sub>1.25</sub>Ti<sub>1.25</sub>O<sub>19</sub>-epoxy (10 wt.%) (SFCTO), both exhibiting distinct high-frequency magnetic and dielectric properties, were investigated using a High Frequency Simulation Software (HFSS) simulation tool. LSMO had a high dielectric constant (ε' >30) within the measurement range (0.1-18 GHz), indicating that dielectric loss mechanisms primarily contribute to EM wave absorption. In contrast, SFCTO is a material capable of significantly absorbing EM waves near 10 GHz due to ferromagnetic resonance (FMR). The simulations were validated by comparing the measured and simulated reflection losses (RL) of an unpatterned LSMO/SFCTO bilayer. The RL spectra were examined by varying the layer thickness and pattern size in three configurations: a continuous LSMO/SFCTO structure, a cross-patterned LSMO on SFCTO, and a square-patterned LSMO on SFCTO. In the continuous LSMO/SFCTO structure, tunable absorption frequency bands were achieved by adjusting the layer thickness. However, it was difficult to achieve broadband absorption due to the reflective characteristics of the high dielectric LSMO layer. The cross-patterned LSMO structure on SFCTO demonstrated broader bandwidth absorption, with layer thickness being more influential than pattern width. The square-patterned LSMO on SFCTO exhibited the best broadband EM wave absorption (max Δ<i>f</i> = 7.39 GHz). These results suggest that broader absorption is achievable by partially covering the high-dielectric layer with patterns on a hexaferrite sheet.

Study on the nano-cutting mechanism of monocrystalline silicon material with an amorphous layer by molecular dynamics simulations

Monocrystalline silicon is prone to brittle fracture during the nano-cutting process. Surface modification through ion implantation to create an amorphous layer on monocrystalline silicon significantly enhances its processability. This paper conducted molecular dynamics simulations to deeply reveal the nanometric cutting mechanism for monocrystalline silicon with an amorphous layer. The influence of the amorphous layer on material removal, subsurface damage, cutting forces, stress distribution, and temperature profiles was analyzed and thoroughly discussed. The calculating results reveal that primary material removal mode transitions from shearing to extrusion under the influence of the amorphous layer. The presence of an amorphous layer can efficiently reduce stress concentration and defects in the nanometric machining process. When the thickness of the amorphous layer equals the cutting depth of the tool, subsurface damage is reduced to approximately 2 nm, indicating that an optimal surface quality is achieved. When the thickness of the amorphous layer reaches more than cutting depth, the hydrostatic stress of the monocrystalline silicon part is significantly lower than the phase transition threshold of 12 GPa, which greatly reduces the occurrence of phase transition. Furthermore, the formation and evolution of shear bands are the primary reasons for the fluctuations in cutting force. The cutting temperature is closely related to structural transformations. The heat generated by shear slip in monocrystalline silicon material is higher than the heat generated by plastic deformation of material in the amorphous layer. Moreover, the heat energy produced by plastic deformation of amorphous layer atoms exceeds that generated by structural transformation of monocrystalline silicon atoms. This work reveals the nanometric cutting behavior of the monocrystalline silicon material with amorphous layer surfaces based on phase transformation. It can provide effective references for the preparation of amorphous layer thickness and selection of cutting parameters in nanometric cutting process of the monocrystalline silicon with amorphous layer surfaces.

Device optimization of all-perovskite triple-junction solar cells for realistic irradiation conditions

All-perovskite two-terminal tandem solar cells, comprising two or more junctions, offer high power conversion efficiencies (PCEs) that exceed the limits of single-junction photovoltaics. Realizing high-efficiency SCs requires carefully optimizing the photoactive layer, front electrodes, and functional layers. Here, we first aim to determine the optimal device architecture, i.e., the perovskites bandgaps and optimum layer thicknesses, for standard test conditions (STCs). We then optimize the energy yield (EY) under realistic outdoor conditions (ROCs), i.e., the overall electrical energy to be expected in one year at a specific location. In the first step, we reference our simulation with two terminal all-perovskite triple-junction SCs (2T3J-PSCs) to previously experimentally realized PSC with a PCE of 20.1% as a benchmark to derive the underlying diode parameters and use our in-house energy yield code combined with a hybrid particle swarm optimization and gravitational search algorithm (PSOGSA) to find the optimal bandgap combination and perovskite layer thicknesses. The optimized SCs with the optimal bandgap combination offer a PCE of 25.1% with a current density of 10.1 mA/cm2. Furthermore, the effect of the other functional layers, such as transparent conductive oxide (TCO), hole transport layer (HTL), and recombination junctions (RJs), is also investigated to enhance the cell performance further. The SCs with optimized layers exhibit improved parameters: PCE of 27.1%, with a relative improvement of 34.8% in the PCE compared with the fabricated cell, and a high current matching a of 10.8 mA/cm2. The numerical results showed that the reported cell can potentially achieve a PCE of 36% at an eVoc/EG ratio of 0.72. However, the optimal parameters may vary in real-world operating conditions due to variations in temperature, humidity, and light exposure. As a result, the optimal energy yield (EY) parameters may differ. Therefore, the energy yield optimizing process is also carried out by considering ROCs in Phoenix, AZ, USA, to find the best parameters under these conditions. We found that the optimum top layer bandgap under ROCs is lower than under STCs due to a bluer, more shifted spectrum in ROCs. After that, the optimized cell under ROCs is tested in several locations exhibiting different climatic conditions (Seattle, Honolulu, Los Angeles, Miami, and Milwaukee). The numerical results show that the optimized cell under ROCs offers an increase in energy yield in several locations compared to conventional single-junction crystalline Si-SCs (PCE = 23.6%) with a high energy yield of 648.2 kWh/m2 in Phoenix, with an improvement of 39.9% in the EY compared to the Si-SC counterpart. Our results provide design guidelines for fabricating a highly efficient triple-junction perovskite SC in the lab and outdoor applications and improve the efficiency of 2T3J-PSCs beyond the 30% limit.