Film Processing Research Articles

Facile Hydrogen‐Bonding Assisted Crystallization Modulation for Large‐area High‐quality CsPbI2Br Films and Efficient Solar Cells

AbstractThe thermally stable inorganic cesium‐based perovskites promise efficient and stable photovoltaics. Unfortunately, the strong ionic bonds lead to uncontrollable rapid crystallization, making it difficult in fabricating large‐area black‐phase film for photovoltaics. Herein, we developed a facile hydrogen‐bonding assisted strategy for modulating the crystallization of CsPbI2Br to achieve uniform large‐area phase‐pure films with much‐reduced defects. The simple addition of methylamine acetate in precursors not only promotes the formation of intermediate phase via hydrogen bonding to circumvent the direct crystallization of CsPbI2Br from ionic precursors but also widens the film processing window, thus enabling to fabricate large‐area high‐quality phase‐pure CsPbI2Br film under benign conditions. Combining with stable dopant‐free poly(3‐hexylthiophene), the CsPbI2Br solar cells achieve the record‐high efficiencies of 18.14 % and 16.46 % for 0.1 cm2 and 1 cm2 active area, respectively. The obtained high efficiency of 38.24 % under 1000 lux illumination suggests its potential in indoor photovoltaics for powering the Internet of Things, etc.

Facile Hydrogen-Bonding Assisted Crystallization Modulation for Large-area High-quality CsPbI2 Br Films and Efficient Solar Cells.

The thermally stable inorganic cesium-based perovskites promise efficient and stable photovoltaics. Unfortunately, the strong ionic bonds lead to uncontrollable rapid crystallization, making it difficult in fabricating large-area black-phase film for photovoltaics. Herein, we developed a facile hydrogen-bonding assisted strategy for modulating the crystallization of CsPbI2 Br to achieve uniform large-area phase-pure films with much-reduced defects. The simple addition of methylamine acetate in precursors not only promotes the formation of intermediate phase via hydrogen bonding to circumvent the direct crystallization of CsPbI2 Br from ionic precursors but also widens the film processing window, thus enabling to fabricate large-area high-quality phase-pure CsPbI2 Br film under benign conditions. Combining with stable dopant-free poly(3-hexylthiophene), the CsPbI2 Br solar cells achieve the record-high efficiencies of 18.14 % and 16.46 % for 0.1 cm2 and 1 cm2 active area, respectively. The obtained high efficiency of 38.24 % under 1000 lux illumination suggests its potential in indoor photovoltaics for powering the Internet of Things, etc.

Exciton dynamics in two-dimensional metal halide perovskite: The impact of film processing.

We investigate the hot carrier and exciton dynamics in two-dimensional (2D) metal halide perovskites using time-resolved spectroscopy. 2D perovskite films were prepared with and without dimethyl sulfoxide treatment to elucidate the effect of film processing techniques on optoelectronic properties. Femtosecond transient absorption measurements reveal that the charge carrier dynamics are different in the two samples, and excitons survive for a longer time in the treated sample than the untreated one. While the early-time carrier dynamics in the untreated sample are dominated by charges trapped by defect states, the hot free carriers govern the dynamics in the treated sample due to fewer defects in it. Morphological and other spectroscopic studies, including time-resolved photoluminescence, further suggest the formation of more defects in the untreated sample. These results can guide the future development of efficient 2D perovskite-based optoelectronic devices.

Spontaneous adsorption effect of graphitic carbon nitride nanosheets to improve sintering behavior of yttria-stabilized zirconia microbeads

Yttria-stabilized zirconia (YSZ) is a ceramic material in which the zirconium dioxide structure is stabilized at room temperature by adding yttrium oxide. However, the YSZ formed by the thick film process on a pre-sintered dense substrate suffers from sintering problems such as different sintering shrinkage rates due to phase transitions and thermal conductivity. This in turn can lead to de-bonding, cracking, delamination, and abnormal growth. We prepared a spherical YSZ green body of approximately 38 μm diameter formed by an organic binder based on a sintered YSZ seed with 15 to 20 μm diameter. In addition, the application of two-dimensional g-C3N4 nanosheets that can be adsorbed on the surface and pores of the green body before the sintering process was evaluated. The YSZ green body with adsorbed surface-modified g-C3N4 nanosheets could be synthesized by stable spontaneous adsorption due to zeta-potential attraction onto the surface of zirconia particles in an aqueous solution. Consequentially, the formation of large grains due to abnormal grain growth was reduced as g-C3N4 was adsorbed. The spontaneous adsorption of nanosheets controls the surface diffusion mechanism by sequentially lowering the energy from a high surface energy in the initial stage of sintering. Uniform grain growth thus can be induced according to the activation energy level of the controlled surface diffusion.

Progress on solution processed Si-nanoparticle solar cells towards new generation photovoltaics

Cost-effective, clean and safe solar energy production is envisaged to solve or at least mitigate climate change problems originated from the current carbon-based power sources addressing both environmental concerns as well as energy needs. Liquid-phase processing of thin films from nanoparticles – as not requiring high temperatures and vacuum – is the optimal strategy towards cost-effective, light weight, flexible and large-area devices. Silicon nanoparticles are in particular important owing to the abundance, chemical stability and low toxicity of this material. This contribution is aimed to highlight the research progresses on free-standing silicon nanoparticles (≤ 50 nm); synthesis, modification and processing towards photovoltaic applications.

Feasibility of molecular dynamics simulation for process parameter guidance of silicon nitride thin films by PECVD

Due to the limitations of the characterization approaches and the relative complex and expensive characteristics of CVD method itself, experimental-based studies are limited, and simulation of SiNx deposition based on molecular dynamics (MD) simulation provides a more convenient and clear solution. In this work, Tersoff potential function containing the interatomic potential for two-body and three-body interactions was utilized to simulate of the deposition process for SiNx thin films by the PECVD. A quick and accurate method basing on Alpha-shapes was proposed to extract surface atoms and the surface roughness of the thin film samples at substrate temperatures of 353, 493, and 653 K were found to be 0.804, 0.794, and 0.721 nm respectively. By analyzing the radial distribution function, it can get that there are small changes in the Si-Si and Si-N bonds at three temperatures. We also found the diffusion phenomenon at the interface, and the atomic diffusion phenomenon at the substrate interface makes the phenomenon of elemental mutation at the interface less rapid. The simulation results confirm that the substrate temperature during deposition has an effect on the adsorption and atomic drift rate of the substrate, which in turn affects the surface morphology of the film.

Solution chemistry strategies to construct a stable MAPbI3 film toward high performance of amplified spontaneous emission

Lead-halide perovskites are being explored as potential light sources for short-distance data communication lasers. However, their practical applications are hindered by defects and poor stability. Ionic liquids (ILs), which are known for their environmentally friendly properties, are being investigated as alternative solvents to address these issues. In this study, methylammonium propionate (MAP), a more viscous IL solvent, was employed to regulate the crystallization process of the perovskite films through the strength of Lewis adducts. Compared with another frequently-used IL, methylammonium acetate (MAAc), the use of MAP solvent was observed to have a significant influence on the morphology and crystalline characteristics of the prepared MAPbI3 film. The findings of this comparative study provide strong evidence for the viability and preferability of using MAP solvent over MAAc in the preparation of MAPbI3 films, specifically for achieving an improved ASE performance and stability. The threshold of the MAPbI3-MAP film was only 12 μJ cm−2, which is lower than one-fourth of that observed for the MAPbI3-MAAc film (56 μJ cm−2) under nanosecond laser excitation. In addition, MAP-based devices can maintain stable ASE output emissions under harsh environments of long-term stimulation and high-humidity preservation.

Impact of Non‐Stoichiometric Phases and Grain Boundaries on the Nanoscale Forming and Switching of HfOx Thin Films

AbstractHfO2 is one of the most common memristive materials and it is widely accepted that oxygen vacancies are prerequisite to reduce the forming voltage of the respective memristive devices. Here, a series of six oxygen engineered substoichiometric HfO2 − x thin films with varying oxygen deficiency is investigated by conductive atomic force microscopy (c‐AFM) and the switching process of substoichiometric films is observed on the nanoscale. X‐ray diffractometry (XRD) exhibits a phase transition from stoichiometric, monoclinic HfO2 toward oxygen deficient, rhombohedral HfO1.7. The conductance of HfO2 − x is increasing with increasing oxygen deficiency, which is consistent with the increasing prevalence of the highly conductive rhombohedral phase. Simultaneously, c‐AFM reveals significant local conductivity differences between grains and grain boundaries, regardless of the level of oxygen deficiency. Single grains of highly oxygen deficient samples are formed at significant lower voltages. The mean forming voltage is reduced from (7.0 ± 0.6) V for HfO2 to (1.9 ± 0.8) V for HfO1.7. Resistive switching on the nanoscale is established for single grains for the highest deficient thin film samples. The final resistance state is thereby dependent on the initial conductivity of the grains. These studies offer valuable insights into the switching behavior of memristive polycrystalline HfO2.

Simulation and Experimental Study on Continuous Wave Fiber Laser Removal of Epoxy Resin Paint Film on the Surface of 6061 Aluminum Alloy

Paint removal is an essential process in the industrial field. Laser technology provides an effective method of paint removal to replace traditional mechanical and chemical methods. This paper establishes a continuous wave (CW) laser thermal paint removal model based on heat conduction theory and Arrhenius’ law. The paint stripping process of epoxy paint film on the surface of 6061 aluminum alloy via CW laser was studied through simulation and experiment. We found that the carbonization of the paint film during the CW laser paint removal process will inhibit the laser paint removal process. Therefore, the paint removal efficiency of the CW laser is limited. The depth of CW laser paint removal increases linearly with the CW laser power density. However, during the CW laser paint removal process, due to the pyrolysis of the paint film and the reflection of the laser by the substrate, the surface temperature of the material first increases and then decreases. In addition, after laser paint removal, the surface roughness of the material after paint removal is reduced due to the melting of the base material. The model established in this article can provide a theoretical reference for studying the CW laser paint removal process.

THE ROLE OF THE PRODUCER IN THE PRODUCTION OF THE FEATURE PROGRAM 'BACKSTAGE' EPISODE 'BEHIND THE SCENES OF THEATER ARTS

This "BACKSTAGE" program is a feature format television program. This Backstage program will discuss all things related to behind the scenes of an event. This program is also very interesting because Backstage itself is a VIP area, not everyone can see and enter the Backstage area. This research has three benefits, namely general benefits, practical benefits and theoretical benefits. as for the purpose of this research is to provide information to the audience both those who watch and those who read this journal the importance of preparations made and prepared to support the smooth running of a Theater Arts. The creator of the work as a Producer creates an event program entitled "BACKSTAGE" in the making of this work is divided into three stages, namely pre-production, production and post-production. in addition to having full rights to a production, Producers also have duties in preparing an idea, conducting research, developing ideas, finding talent, recce, preparing tools, assisting the reading process, licensing production locations, preparing tools needed by each department and making production plans starting from schedules, drafting budgets, job descriptions, and real budgeting. In addition, the producer also controls during the filming and editing process, consumption, prepares accommodation and To avoid over time during the production process, the Producer makes a crew call that is adjusted to the hourly needs of each department.

Numerical ellipsometry: Artificial intelligence for real-time, in situ absorbing film process control

Ellipsometry is a material analytical method in which the desired parameters, for example, film thickness and index of refraction, are related to the instrument measurements through Maxwell’s equations, light wavelength, and measurement geometry. Consequently, obtaining the desired parameters has required solving the model equations using a wide variety of methods. A commonly used method is least squares curve fitting, frequently the Levenberg–Marquardt method. This numerical method depends upon not only the model but also the initial estimates of solution, the possible interference of local minima, and the algorithm stopping conditions. Being iterative, it also takes nonzero time. The work here demonstrates the use of artificial intelligence in the form of a multilayer perceptron artificial neural network to avoid these problems and find solutions in the millisecond time scale. This noniterative, stable, and fast performance lends itself to real-time, in situ monitoring of thin film growth. Examples for thin (up to 30 nm) films will be given using a multilayer perceptron configuration consisting of four input and four output neurons with two hidden layers of 40 neurons each. Solutions are predicted by the artificial neural network at each wavelength independently and do not rely on fitting functions which express a relationship between optical properties and wavelength.

Dry Laser‐Induced Graphene Fractal‐like ECG Electrodes

AbstractFractal‐like geometries applied to biosignal‐electrodes design show great potential for enhancing the signal acquisition of sensing systems. This study reports a novel approach for flexible, silver‐free, and dry fractal‐like electrodes based on Laser‐Induced Graphene (LIG) obtained through laser photothermal processing of a commercial polyimide film. This one‐step mask‐less manufacturing process enables the simple fabrication of natural and optimized fractal‐like shapes inspired by actual snowflake patterns. To ensure a reliable and standardized connection to the measurement unit, the electrodes are equipped with a snap terminal. The electrodes are structurally characterized using various techniques including Scanning Electron Microscopy (SEM), Raman spectroscopy, and X‐ray Photoelectron Spectroscopy (XPS). By benchmarking the performance of these electrodes against Ag/AgCl wet commercial electrodes and LIG electrodes shaped as commercial ones, a heart rate‐monitoring accuracy of over 96.8% is achieved, with high specificity, positive prediction, and sensitivity, surpassing the 95.8% achieved by conventional commercial electrodes. These results demonstrate the efficacy of fractal‐based designs in combination with LIG‐based transduction, offering flexible and cost‐effective electrocardiogram (ECG) electrodes with improved performance compared to traditional wet electrodes.

Types of Visibility: Disruption, Consent & Contemporary Politics

This paper analyses representations of the coming-of-age process in contemporary narrative films that challenge dominant social and political ideologies. Through an intersectional analysis of Tomboy (2011), Girlhood (2014), and Portrait of a Lady on Fire (2019), all of which were directed by Céline Sciamma; Inxeba (2017) by John Trengove, and Moffie (2019) by Oliver Hermanus, I demonstrate how specific scenes and sequences expose and critique gender, race, class, and sexuality norms. Drawing from feminist, queer, and postcolonial theories, I identify three types of visibility across the films: disruption, consent, and contemporary politics. The analysis reveals how the selected films contest dominant cinematic gazes and scopic regimes by giving visibility to diverse identities and experiences. I argue that this study yields generative insight into the complexities of the coming-of-age process on the body as it is represented in contemporary narrative film.

Electrochemical Investigation of Chloride Ion-Induced Breakdown of Passive Film on P110 Casing Steel Surface in Simulated Pore Solution: Behavior and Critical Value Determination

In the petroleum industry, the casing steel is fixed with a cement sheath to ensure reliable service in demanding conditions characterized by high temperature, high pressure, and exposure to multiple types of media. After the hydration of the cement, a porous material is produced with a highly alkaline solution filling the pores, commonly referred to as the pore solution. The casing will form a protective passive film when in contact with a highly alkaline pore solution. Nevertheless, once the cement sheath cracks, chloride ions in the stratum will pass through the cement sheath to the surface of the casing. When chloride ions accumulate to a certain concentration, the passive film will be destroyed, without exerting a protective influence on the substrate. After chloride ions come into direct contact with the casing, the casing is prone to severe failure due to corrosion perforation. The casing failure can cause a blowout outside the casing and even scrapping of the oil well. Controlling casing corrosion and ensuring casing integrity relies on understanding the critical chloride ion concentration that can cause the degradation of the passive film. Therefore, to assess the electrochemical properties and analyze the damage process of the passive film under varying chloride ion concentrations, several characterization techniques were employed. These included potential–time curves (E-t), polarization curves, electrochemical impedance spectroscopy (EIS), and Mott–Schottky curves. In addition, the composition of the passive film on the surface of the P110 casing steel was qualitatively analyzed using X-ray photoelectron spectroscopy (XPS). To further understand the surface morphology of the P110 casing steel, scanning electron microscopy (SEM) was used.

Ultraclean Interface of Metal Chalcogenides with Metal through Confined Interfacial Chalcogenization.

Acquisition of defect-free transition metal dichalcogenides (TMDs) channels with clean heterojunctions is a critical issue in the production of TMD-based functional electronic devices. Conventional approaches have transferred TMD onto a target substrate, and then apply the typical device fabrication processes. Unfortunately, those processes cause physical and chemical defects in the TMD channels. Here, a novel synthetic process of TMD thin films, named confined interfacial chalcogenization (CIC) is proposed. In the proposed synthesis, a uniform TMDlayer is created at the Au/transition metal (TM) interface by diffusion of chalcogen through the upperAu layer and the reaction of chalcogen with the underlying TM. CIC allows for ultraclean heterojunctions with the metals, synthesis of various homo- and hetero-structured TMDs, and in situ TMD channel formation in the last stage of device fabrication. The mechanism of TMD growth is revealed by the TM-accelerated chalcogen diffusion, epitaxial growth of TMD on Au(111). We demonstrated a wafer-scale TMD-based vertical memristors which exhibit excellent statistical concordance in device performance enabled by the ultraclean heterojunctions and superior uniformity in thickness. CIC proposed in this study represents a breakthrough in in TMD-based electronic device fabrication and marking a substantial step toward practical next-generation integrated electronics.

Passivating A-Site and X-Site Vacancies Simultaneously via N-Heterocyclic Amines for Efficient Cs2AgBiBr6 Solar Cells.

To address the toxicity and stability issues of traditional lead halide perovskite solar cells (PSCs), the development of lead-free PSCs, such as Cs2AgBiBr6 solar cells, is of great significance. However, due to the low defect formation energy of Cs2AgBiBr6, a large number of vacancies, including A-site vacancies and X-site vacancies, form during the fabrication process of the Cs2AgBiBr6 film, which seriously damage the performance of the devices. The traditional phenylethylammonium (PEA) cation, mainly focusing on passivating A-site vacancies, is incapable of reducing X-site vacancies and so results in a limited performance improvement in Cs2AgBiBr6 solar cells. Herein, inspired by the capability of the Lewis base to coordinate with metal cations, a series of N-heterocyclic amines are introduced to serve as a dual-site passivator, reducing A-site and X-site vacancies at the same time. The highest power conversion efficiency of modified Cs2AgBiBr6 solar cells has been increased 36% from 1.10 to 1.50%. Further investigation reveals that the higher electron density of additives would lead to a stronger interaction with metal cations like Ag+ and Bi3+, thus reducing more X-site defects and improving carrier dynamics. Our work provides a strategy for passivating perovskite with various kinds of defects and reveals the connection between the coordination capability of additives and device performance enhancement, which could be instructive in improving the performance of lead-free PSCs.

Surface-enhanced Raman scattering to realize the phonon processes in Ag nanoparticles-decorated CdS thin film

Abstract Surface-enhanced Raman spectroscopy (SERS) technique can achieve an ultra-high sensitivity (i.e., down to the single-molecule level) via coinage-metal nanostructures such as silver, gold, copper, etc. In this work, a geometry is proposed that consists of silver nanoparticles (AgNPs) decorated on cadmium chloride (CdCl2) annealed cadmium sulfide (CdS) thin film on a glass substrate. A strong SERS enhancement in AgNPs on CdCl2 annealed CdS thin films is achieved, which is twelve times larger than the scattering from the bare CdCl2 annealed CdS thin film. The improved SERS signal allows us to observe fundamental phonon processes in CdCl2 annealed CdS thin film. Moreover, a finite difference time domain (FDTD) method is used to understand the underlying SERS physics. By using the FDTD method, robust electromagnetic field localization in the nanogap between AgNPs and at the contact point of Ag NPs and CdS thin film is studied.

Processing of diamond films with azimuthal texture on silicon wafer for quantum systems

Processing of diamond films with azimuthal texture on silicon wafer for quantum systems

Transient ablation topography of a thin chromium film after ultrashort pulsed laser irradiation in the spallation and phase explosion regime

Time-resolved imaging pump–probe reflectometry is an established technique to characterize the dynamic processes occurring during the material ablation upon ultrashort pulsed laser irradiation. In the phase explosion regime, however, the presence of an expanding liquid–vapor mixture on top of the ablated material makes an unambiguous determination of the transient ablation topography almost impossible, especially when only front-side pump–probe reflectometry is used. To circumvent this limitation, the front-side reflectometry was complemented by rear-side reflectometry, where the probe radiation does not interact with the liquid–vapor mixture, and the underneath ablation kinetics of the material becomes observable. To interpret the measured front- and rear-side reflectances, an optical multilayer model of the ablation process was developed. Its applicability is demonstrated on a thin chromium film that was ablated by a single pump pulse. The optical model replicates the Newton rings measured during spallation and phase explosion very well, which allows the reconstruction of the transient ablation topography. The combination of the front- and rear-side reflectometry with modeling offers a valuable tool for studying the ablation processes in thin metal films, because it overcomes the challenges of the phase explosion regime, and thus enhances the understanding of material dynamics upon laser irradiation.

Experimental assessment of lamination processing method for liquid-based hybrid PV/T modules

Due to the lack of in-depth research on lamination processing methods for PV/T technology, typical flat-plate PV/T modules still face severe lifespan issues that require urgent solutions. Thus, this study proposes a specialized two-stage lamination process method. The efficacy of this process flow in addressing the challenging issue of microscopic hidden cracks in PV cells, which commonly occurred during the processing of PV/T modules, was confirmed through a comprehensive electroluminescence testing procedure. An analysis was conducted to examine the interrelationship between the thermal pressing process, peel strength, and crosslinking degree of the hot-melt adhesive film on both the absorber plate and external surface of the transparent TPT (Tedlar/PET/Tedlar) layer. The results indicated that a high level of peel strength (50 N/cm to 80 N/cm) was achieved between the adhesive film and absorber plate with a selective absorption coating, while ensuring compliance with crosslinking requirements and preventing bubble issues. Therefore, the novel process method proposed in this paper for PV/T modules can effectively address the bottleneck of lifespan issues that have remained unresolved in PV/T technology for years.