Edge Of Film Research Articles

Band edge engineering of lead halide perovskites using carboxylic‐based self‐assembled monolayer for efficient photovoltaics

AbstractPerovskite solar cells are promising candidates for low‐cost and efficient photovoltaic markets, but their efficiency is usually limited by the non‐radiative recombination losses at the mismatched interface of perovskite and transport layers. Herein, we show that the band edges of perovskite thin films can be on‐demand engineered by a series of carboxylic‐based self‐assembled monolayers. Experimental and theoretical studies indicate that the functionalized perovskite inherits the polarity of the monolayer with linear dependence of work function on the molecular dipole moments, which enables the management of interfacial charge transport process. Solar cells with 4‐bromophenylacetic acid SAMs achieve about 6.48% enhancement in power conversion efficiency with the champion values over 23%.

Real-time three-dimensional monitoring and analysis of perovskite solar cell using short wavelength infrared digital holography

The quality and crystallization process of all-inorganic perovskite films play a crucial role in the performance of solar cells. However, traditional detection methods lack three-dimensional depth information and real-time capabilities, hindered by strong visible light absorption, posing challenges to research. Here, a simple digital holography technique is proposed that offers real-time, nondestructive, three-dimensional phase imaging with low absorption characteristics in the short-wave infrared range. The use of short-wave infrared reduces the negative impact of visible light and vibrations in the environment on detection accuracy, while being nearly non-absorbing. The proposed method operates at a speed of 15 Hz, combining a lensless vertical structure, holographic reconstruction algorithm, and phase unwrapping algorithm to achieve real-time three-dimensional observation without image distortion and with low noise of the crystallization process of CsPbBr3 perovskite quantum dots (PQDs)/ethylene-vinyl acetate solution, which crystallizes in 39 s. Subsequently, employing minimum bounding rectangle, field stitching, intensity registration, and sub-pixel level calibration algorithms, real-time characterization is performed on the large-sized droplet of polymethyl methacrylate-matrix-encapsulated CsPbBr3 perovskite quantum dots, which has a crystallization time of 1285 s, without being limited by the field of view. Finally, using this system, the surface quality of the film is assessed, revealing fluctuations at the edge and fabrication defects of the perovskite film. Experimental results demonstrate the potential of short-wave infrared digital holography in enhancing the film formation process and quality inspection. By leveraging this technology, advancements in the development of high-performance all-inorganic perovskite solar cells can be fostered, optimizing global energy output.

EBT3 Radiochromic film response in time-dependent thermal environment and water submersion conditions: Its clinical relevance and uncertainty estimation

AimThis study aimed to find the thermal and humidity-dependent behavior of EBT3 film. The changes in the film sensitivity as well as the dosimetric region of interest in the small-size film due to its storage and setup condition were evaluated. Material and methodsThree sets of films were kept at three different thermal storage conditions. 15 films from each set were kept at 2 °C, 20 °C, and 40 °C storage conditions for 24 h and 48 h pre- and post-irradiation. The humidity effect (water submersion) on the film in terms of the film's edge diffusion, and change in the optical density at the central region of the film was estimated by keeping the films underwater. ResultsThe mean relative film sensitivity was found 1.107 ± 0.123 and 0.966 ± 0.028 respectively for the films stored at 40 °C and 2 °C with respect to the sensitivity of the films that were kept at room temperature (20 °C) each for 48 h. The dosimetric result shows that the measured dose in the dose range (2–20 Gy) was overestimated by 7.01 % (percentage mean dose difference (MDD)) in the films stored at 40 °C for 48 h. In contrast, it was underestimated by −4.54 % (MDD) in the films stored at 2 °C for 48 h compared to those kept at an ambient room temperature of 20 °C (MDD = 0.24%). The water-diffusion rate at the border of the EBT3 film used in this study was 0.23 mm/h. An increment of 6.8% in the optical density at the central region of the film was observed for the unexposed control film kept underwater for 24 h. The combined standard uncertainty due to five different sources of uncertainties was 2.91%. ConclusionThe sensitivity of the EBT3 film kept at 40 °C is always higher (overestimate) whereas lower (underestimate) for the films kept at 2 °C as compared to the films at normal room temperature. The correction for the changes in the net optical density due to its storage condition (thermal effect) and the dosimetry condition of water submersion (humidity effect) must be incorporated into the current protocols of film-dosimetry if the facility cannot have temperature-controlled film storage environment and if the film immersion under water is more than 4 h.

Enhanced propagation of free films with fast spread-out phenomena under the influence of megahertz surface acoustic waves

In this study, a novel approach for enhancing the rapid spreading of free liquid film on lithium niobate (LiNbO3) substrate under megahertz (MHz) surface acoustic wave (SAW) excitation is presented by treating it with surfactants. Through the design of a specific interdigital transducer structure, it was discovered that exciting the SAW at a frequency of 32.3 MHz can achieve optimal spreading performance for water droplets on the surface of surfactant-treated LiNbO3 substrate. The maximum average velocity reaches 1.76 mm/s at position P2 = 1250 μm in the water film front, and the stable film spreading speed shows a 204.9% increase compared to the existing research. Simultaneously, through the investigation of the spreading experiment phenomenon of silicone oil and de-ionized water droplets at varying frequencies, we have discovered the dynamic mechanism of “reverse phase” propagation in liquid film for the first time. This entails that the advancing edge of the wetting film demonstrates a spreading motion law that is opposite to the traditional spreading phenomena, with the spreading velocity in the central exceeding that on both sides. Our research demonstrates that this microfluidic device developed by SAWs enhances the spreading efficiency of the free films, enabling rapid expansion of the target liquid to form a high-surface area film layer. This advancement holds promise for overcoming the limitations of low sensitivity and short response time in the field of rapid pathological diagnosis in contemporary medicine.

Enhancing flexible electronics: Unveiling the role of strain rate in the performance of molybdenum-coated PET films

This work analyzes the mechanical and electrical properties of molybdenum (Mo) thin films at 100 and 200 nm thicknesses under different strain and strain rate circumstances. The study examines Mo film deposition by RF magnetron sputtering on PET substrates and their mechanical stress behavior. The investigation reveals distinct patterns of crack initiation and propagation, where primary cracks predominantly appear perpendicular to the direction of applied strain, and secondary cracks develop due to stress redistribution, displaying a complex interplay between film thickness, strain rate, and crack morphology. A key finding of this study is the observation of more advanced and irregular crack patterns in thicker films (200 nm) subjected to higher strain rates (1000 mm/min), suggesting a heightened sensitivity to mechanical stress and a more chaotic fracture process compared to thinner films or those under lower strain rates. Additionally, instances of film edge delamination, particularly under high strain conditions, highlight the challenges in maintaining film-substrate adhesion and integrity under extreme mechanical deformation. The research provides critical insights into the mechanical robustness and electrical performance of Mo thin films, emphasizing the influence of microstructural properties, deposition parameters, and external stressors on their applicability in high-tech industries. The findings underscore the importance of optimizing deposition techniques and understanding material behavior under stress to enhance the durability and reliability of Mo thin films in practical applications, ranging from semiconductor devices to photovoltaic systems.

Thickness measurement of thin films using atomic force microscopy based scratching

Thin-film thickness measurements using atomic force microscopy (AFM) comprise two steps: 1. AFM scratching in order to produce an exposed film edge, and 2. subsequent AFM measurement of the corresponding step height across the exposed edge. Although the technique is known, many open questions have limited its wider applications. In order to clarify the open questions, here we first demonstrate how to determine the normal force applied during the scratching in contact mode needed to completely remove films from substrates. In order to determine film thickness from processed AFM images, we discuss two procedures based on the histogram method and polynomial step-function fitting. Mechanisms of the scratching process are elucidated by the analysis of lateral forces and their enhancement during the film peeling. Phase maps of scratched domains recorded in amplitude modulation AFM (tapping) mode display a clear contrast compared to pristine films. Therefore, we suggest their utilization as simple indicators of spatial domains with completely removed films. As an example, here the measurements were done on polymer films fabricated by layer-by-layer deposition of oppositely charged polyelectrolytes composed of poly(allylamine hydrochloride) and poly(sodium 4-styrenesulfonate), while the applicability of the presented method on other materials is discussed in detail.

Unperforated film-covered planting contributes to improved film recovery rates and foxtail millet grain yields in sandy soils

Plastic film mulching improves the soil water content and temperature and, thus, contributes to enhanced grain yield in arid and semi-arid areas, such as Northwest China. However, in traditional film-covering methods, plastic films are difficult to recycle, causing environmental issues. Therefore, developing cultivation methods with enhanced film recovery rates is important for sustainable agricultural development. Here, we evaluated how the planting method affected the soil temperature, water content, film recovery rate, and grain yield by applying the following three planting patterns to the traditional crop, foxtail millet, in 2021–2022: no plastic film mulching (NP), plastic film mulching (MP), and planting on the film edge (PFE); in the latter, holes were not punched in the film and crops were planted approximately 5 cm from the film edge. The results for 2021 showed that the biomass ranged from 27.69 g to 33.76 g per plant, and the biomass was increased by 21.9% and 3.2% in PFE compared with NP and MP, respectively. However, in 2022, the biomass increased in PFE by 52.5% and 17.7% compared with NP and MP, respectively. In 2021, the highest grain yield was observed in PFE (2480 kg/hm2), followed by MP (2470 kg/hm2) and NP (2343 kg/hm2); in 2022, a significantly higher grain yield was observed in PFE than that in MP and NP. Although the soil temperature increased in PFE, it was not as high as in MP. The relatively higher soil temperature increased the root growth process, stimulated the production of root exudates (acetic acid and citric acid), and increased the soil enzyme (sucrase and urease) activity. Increases in organic acids and soil enzymes assisted in the decomposition of soil organic matter and induced relatively higher levels of available nutrients, such as nitrogen and phosphorus, and the higher root reuse rates contributed to higher grain yields. In addition, fewer holes were punched in the film of the PFE model, which improved film recovery, and the recovery rate of PFE was higher than that of MP. These results indicate that the proposed unperforated film-covered planting pattern is suitable for millet production in sandy soil.

Progress in Polyhedral Oligomeric Silsesquioxane (POSS) Photoresists: A Comprehensive Review across Lithographic Systems.

This paper offers a comprehensive overview of the polyhedral oligomeric silsesquioxane (POSS) and POSS-based composites within the realm of photoresist resin. The study involves a systematic exploration and discussion of the contributions made by POSS across various lithographic systems, with specific emphasis on critical parameters such as film formation, sensitivity, resolution, solubility, and edge roughness. These lithographic systems encompass X-ray lithography (XRL), deep ultraviolet nanoimprint lithography (DUV-NIL), extreme ultraviolet lithography (EUV), and guided self-assembled lithography (DSA). The principal objective of this paper is to furnish valuable insights into the development and utilization of POSS-based photoresist materials in diverse lithographic contexts.

Discrete Element Method–Multibody Dynamics Coupling Simulation and Experiment of Rotary Tillage and Ridging Process for Chili Pepper Cultivation

Rotary tillage, ridging, and mulching are commonly used cultivation methods for crops such as chili peppers, tomatoes, and strawberries in the arid regions of Northwest China. An integrated machine for rotary tillage, ridging, and mulching was designed by considering the growth characteristics of pepper root systems and the agronomic requirements of ridge beds. The structural parameters and their value ranges for key components such as the rotary tillage device and the ridging device were determined. By introducing the Bonding contact parameter, the soil cohesion between soil particles during the process of rotary tillage and ridging can be simulated. A coupled simulation model using the Discrete Element Method (DEM) and Multibody Dynamics (MBD) is established. The experimental factors selected were rotary tillage depth, ridging roller speed, and machine forward speed. The evaluation indexes were the traction resistance of the stemming roller and the soil compactness of the ridges. A response surface Box–Behnken Design test was carried out to obtain the best working parameters of the rotary tillage and ridging process for chili pepper cultivation as follows: the rotary tillage depth was 176 mm, the ridging roller speed was 283.71 r/min, and the machine forward speed was 0.55 m/s. Field experiments with optimal parameters showed that the ridge top width was 549.2 mm, the ridge bottom width was 750.5 mm, the ridge height was 222.9 mm, the ridge spacing was 1173.1 mm, the surface smoothness of the ridge was 12.3 mm, the width of soil covering the film edge was 76.3 mm, the stability coefficients of the ridge size parameters were all above 91.73%, and the soil compactness after operation was 60.82 KPa. All indicators meet the requirements for the rotary tillage and ridging cultivation of chili peppers in arid regions, providing reference for the design of rotary tillage and ridging mulching implements and the development of sustainable agriculture.

Magnetic anisotropy and ferromagnetic resonance in inhomogeneous demagnetizing fields near edges of thin magnetic films

Using local ferromagnetic resonance spectroscopy, we have studied the magnetic properties near edges of thin tangentially magnetized permalloy films, in which a well-defined uniaxial magnetic anisotropy was induced perpendicular to one of the edges. In the experiment, two samples with thicknesses of 90 and 300 nm and with slightly different compositions were examined. To explain the magnetization dynamics near edges, we propose a simple yet effective model of a film in the form of a rectangular prism, which yields the modified Kittel formula for the resonance frequency. In this formula, the locally averaged distance-dependent demagnetizing field that emerges near the edges is included as an additional uniaxial anisotropy term. The measurements reveal that at a certain distance from the edge, the resulting (apparent) anisotropy, determined from the angular dependencies of the resonance field, almost vanishes. Moreover, its easy axis reorients to become parallel to the edge. The model predictions agree well with these results, proving that the main resonance mode behavior near the film edges can be accurately described by introducing additional effective uniaxial anisotropy, provided the measuring area is relatively large. However, for the thick (300 nm) sample, additional precession modes are also observed. These modes distort the angular dependence of the main mode, thus demonstrating the limitations of the model.

Enhancement of optical absorption in multiferroic 0.5PZT-0.5PFN thin films: Experiments and first-principles analysis

Multiferroic compounds have gained research attention in the field of ferroelectric photovoltaics due to the presence of transition-metal d states from magnetic ions, which tend to reduce the bandgap value. In this work, 0.5Pb(Zr0.52Ti0.48)O3–0.5Pb(Fe0.5Nb0.5)O3 [PZTFN0.5] thin films were synthesized using a sol-gel route to investigate the effect of iron doping on optical and multiferroic properties. For comparative analysis, the end-member compositions, Pb(Zr0.52Ti0.48)O3 [PZT] and Pb(Fe0.5Nb0.5)O3 [PFN], were also synthesized under identical conditions. Our results revealed that the incorporation of Fe3+ ions into the PZT lattice not only induces multiferroic behavior, but also effectively enhances the optical absorption of the material in the visible light region. Optical transitions at ∼3.0 eV (∼2.4 eV) and ∼2.7 eV (∼2.2 eV) for the direct (indirect) bandgap were determined for PZTFN0.5 and PFN, respectively, indicating that the absorption edges of the iron-containing films result more promising than PZT (direct Eg∼3.6 eV) for photovoltaic applications. Both PZTFN0.5 and PFN thin films exhibit multiferroic behavior at room temperature, with different electric and magnetic properties. While PZTFN0.5 presents saturated hysteresis loops with remanent polarization values around 10 μC/cm2 and magnetization of 1.6 emu/cm2, PFN displays significantly larger remanence (31 emu/cm2) but poorer ferroelectric properties due to the presence of leakage. Microscopic insights into the structural and electronic properties of the PZTFN0.5 solid solution were provided from first-principles calculations.

Study on Marangoni explosion of binary mixtures in liquid layer

In this work, the process of forming micro-droplets due to instability and fragmentation after short chain alcohol solution spreads on the surface of oil layers is studied. Based on the free energy theory of the liquid-liquid interface, the relationship between the binary mixtures spreading on the surface of the liquid layer is derived, and the concentration range of short chain alcohol solution spreading as a thin film on the surface of the oil layer is calculated from the Hiskovsky formula. The Malangoni flow caused by the difference in evaporation rate between the center and edge of the droplet film perturbs the boundary of the liquid film, causing finger-shaped liquid columns to grow at the edge when the droplet spreads to its maximum. In this work, the expression for the critical wavelength and maximum wavelength of boundary instability are derived based on the perturbation model, and the reason for finger shaped liquid column fragmentation is explained based on the Plateau Rayleigh instability. A concentric cylindrical shell liquid column model is established to simplify the calculation and predict the location range of “droplet explosion” of droplets with different viscosity ratios on the liquid layer. Through theoretical calculations and experimental verification, it is found that the alcohol solution fragmented into small droplets within a length range of 4.51–5.98 times the width of the liquid column. This study provides theoretical guidance for existing application fields such as film forming technology and coating technology. The hypotheses, assumptions, and simplified models preliminarily verified experimentally provide solutions for some technical difficulties in the research fields of micro reactions and nanoparticle preparation in chemical industry.

Wide-field imaging of the magnetization process in soft magnetic-thin film using diamond quantum sensors

The magnetization process of a soft magnetic CoFeB-SiO2 thin film was imaged using diamond quantum sensors with perfectly aligned nitrogen-vacancy centers along the [111] direction formed by CVD. Around the film edge, the easy and hard axes directions exhibited different responses to the external magnetic field, consistent with ones observed by magneto-optical Kerr effect microscopy. Moreover, quantum diamond imaging could observe discontinuous magnetization along domain walls as non-uniform magnetic charges (MCs). Quantum diamond imaging would help in visualization through MCs, such as irregularity in the material and relative orientation of magnetizations in neighboring domains.

Edge cracking behavior of Y2O3 films based on the stress intensity factor

Hastelloy C-276 alloy is the preferred substrate for YBa2Cu3O7-δ (YBCO) coated conductors prepared by Ion-beam-assisted deposition (IBAD) route, but its surface is too rough to meet application requirements. Y(CH3COO)3·4H2O precursor solution has a low flattening efficiency, and its film edges are prone to crack formations. In this paper, a model for the stress intensity factor was established to study the effect of the presence of cracks on film stress. The simulation results showed that increasing the coating thickness reduced the overall stress, but increased the stress concentration at the crack. The larger bottom layer defects also made it easier for cracks to be generated. Then, 10-m long Hastelloy C-276/Y2O3 strips were prepared by colloidal-solution deposition planarization (CSDP), with an average surface roughness Rq of 0.427 and only 10 coating layers. This improved the flattening efficiency by 40 %, and a CeO2 layer with a good biaxial texture was finally prepared.

Dynamic behavior of droplet impacting on a moving surface

The research specifically analyzes the characteristics of the impacting droplet and its behavior on the moving surface. The experimental results demonstrate that the droplet impact can be divided into two stages: spreading and stretching. The surface shear force is found to play a decisive role in the droplet's dynamic behaviors. Specifically, the surface shear force inhibits liquid fingers at the front edge of the liquid film during the spreading stage, but promotes the extension of liquid fingers at the trailing edge of the droplet during the stretching stage. The surface shear force has a significant influence on the longitudinal spreading factor of the droplet during the spreading stage. The transverse maximum spreading time decreases with the increase of shear weber number. The wake flow of the droplet is mainly divided into four types: wetting deposition, fracture separation, single finger, and multi-fingers. Additionally, the ratio of the horizontal maximum spreading factor to the longitudinal spreading factor in the same time is found to be positively correlated with the ratio of the two weber numbers. The research findings contribute to the fundamental understanding of droplet dynamics on moving surfaces and highlights the importance of considering surface shear force in understanding droplet dynamics and provides a basis for further research in this field.

Photonic Hook Initiated Using an Air–Liquid Interface

In this paper, we demonstrate a novel photonic hook being initiated using an air–liquid interface (ALI). This bent light focus is produced by immersing a dielectric micro-cylinder partially at the edge of a thin liquid film whose thickness is smaller than the diameter of the micro-cylinder. Unlike the well-known properties of normal near-field focuses, this photonic hook propagates horizontally in the liquid along the ALI at specific depths and does not require the material processing of microscopic particles or the modulation of light irradiation for initiation. A morphological analysis indicates that the contrast in the refractive indexes of the ALI causes this phenomenon at the shadow end of the micro-cylinder with a transverse dimension smaller than the diffraction limit. Compared to previously discovered photonic hooks, the unique setup of this photonic hook can generate a force field that enables optical trapping in the region slightly beneath the ALI, and the related optical pressures have been simulated.

Surfactant transport upon foam films moving through porous media

In the context of foam improved oil recovery or foam-based soil/aquifer remediation, a model is presented for evolution of surfactant surface concentration on foam films moving through porous media. The model exploits an analogy between surface transport behaviour in foam fractionation and surfactant transport behaviour for foam in porous media. Films either stretch as they move from pore throat to pore body, or shrink when moving from pore body to pore throat: this stretching/shrinking then influences surfactant concentration. In addition, Plateau borders at the edges of films can supply surfactant to films, or receive surfactant from them. The model is solved numerically and key parameters governing its behaviour are identified. Parameter regimes are encountered, corresponding to modest stretching or shrinkage rates, in which surfactant concentration on films is predicted to be closely coupled to surfactant concentration in Plateau borders. Alternate parameter regimes are encountered, corresponding instead to fast stretching or shrinkage rates, in which surfactant concentration on films is predicted to become independent of surfactant concentration in Plateau borders. Asymptotic solutions available in each of these regimes are compared with numerical solutions. A preliminary comparison between the model predictions and experimental data from literature is also described. The appeal of the model is that predictions can be made comparatively simply. Indeed the model can predict when foam films might become significantly depleted in surfactant, possibly leaving films liable to breakage, which would then be detrimental to foam in porous media applications.

棉花精量播种机铺膜质量监测系统设计与试验

To realize real-time monitoring of film laying process of cotton precision planter and improve intelligent level of cotton precision planter, based on advanced morphological filtering method and graphical programming of Labview software, a film laying quality monitoring system of cotton precision planter is designed. Using the Vision Assistant visual assistant, the system uses a color extraction function to convert colors to grayscale images. It uses LOOKup Table function and FFT filter function to perform grayscale transformation, binarization and advanced morphological filtering on it respectively. It then uses basic morphology to acquire various components in the plastic film image. It realizes the monitoring of parameters such as the width of the daylighting surface, the side length or seam length of the mechanical damaged part, and the width of the film edge covering soil. The performance test results of the film laying quality monitoring system showed that the system worked stably and reliably, the average monitoring accuracy of the width of the lighting surface and the width of the film edge covering soil reached more than 95%, and the average monitoring accuracy of the side length or the length of the seam at the mechanical damage part reached more than 88%. It solved the problems of difficulty in recognizing the similarity between the plastic film and the background interferer (soil, etc.) and could accurately detect the quality of the cotton film in real time. It effectively improved the operation quality and working efficiency of the cotton precision planter and met the practical requirements of film laying monitoring.

Design and Experiment of the Combined Machine for Transplanting Outcrop of Codonopsis with Micro Ridge Covered with Film

In response to the problem of no supporting equipment for the cultivation of Codonopsis in the hilly and mountainous areas of northwest China, a combined machine for transplanting outcrop of Codonopsis with micro ridges covered with film is designed. The key components of the prototype are analyzed and designed, and the structures and working parameters of the seedbed preparation device, seedling-casting device, rotary tillage soil-covering device, film-covering device, seedling head burial, and film edge soil-covering device are determined. The transmission system scheme is established, and the working mechanism of the core components is analyzed. Field experiments show that when the target seedling spacing is 4.4 cm and the machine moves forward at a speed of 0.1, 0.15, and 0.2 m/s, the variation coefficient of planting spacing and the qualification rate of planting depth meet the standard requirements. The qualified rate of planting posture and film side outcrop are greatly affected by the operating speed of the machine and decrease with the increase in operating speed. When the operating speed reaches 0.1 m/s, the average variation coefficient of planting spacing is 0.08% and the average qualified rate of planting depth, planting posture and film side outcrop is 95.83%, 94.17%, and 93.33%, respectively, which shows that the operating performance is better than that of the operating speeds of 0.15 m/s and 0.2 m/s. This study provides a new reference for the theoretical research and design of mechanized and automated transplanting machinery for Codonopsis seedlings.

Magnon-Optic Effects with Spin-Wave Leaky Modes: Tunable Goos-Hänchen Shift and Wood's Anomaly.

We demonstrate numerically how a spin wave (SW) beam obliquely incident on the edge of a thin film placed below a ferromagnetic stripe can excite leaky SWs guided along the stripe. During propagation, leaky waves emit energy back into the layer in the form of plane waves and several laterally shifted parallel SW beams. This resonance excitation, combined with interference effects of the reflected and re-emitted waves, results in the magnonic Wood's anomaly and a significant increase of the Goos-Hänchen shift magnitude. This yields a unique platform to control SW reflection and transdimensional magnonic router that can transfer SWs from a 2D platform into a 1D guided mode.