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Modulation of Growth Kinetics of Vacuum-Deposited CsPbBr <sub/>3</sub> Films for Efficient Light-Emitting Diodes
摘要： Due to its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX3 (X=I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr3 polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition flux which, along with growth temperature, determines the nucleation rate and therefore eventual grain structure. A correlation between deposition flux and average grain size was noted except for a very large deposition flux when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr2 films. The growth conditions that produced a nano-scale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr3 light emitters, we demonstrate a green light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr3 films for high efficiency LEDs.
关键词： Light-emitting Diodes,Thermal co-evaporation,Perovskites,Vacuum deposition,LEDs,CsPbBr3
更新于2025-09-12 10:27:22
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p-type Cu3BiS3 thin films for solar cell absorber layer via one stage thermal evaporation
摘要： Ternary copper sulphides, especially copper-bismuth-sulphide (Cu-Bi-S), are alternative solar absorber materials due to their earth-abundant and non-toxic constituent elements, compared to the conventional copper indium gallium sulphide and cadmium telluride films. In this study, Cu-Bi-S thin films were deposited onto soda lime glass substrates using a one stage co-evaporation process from Cu2S and Bi2S3 sources, with the deposition temperatures varied from room temperature to 400°C. X-ray diffraction analysis confirmed that Cu3BiS3 was the dominant phase in the Cu-rich films, and the crystalline quality of the films was significantly improved with increasing the deposition temperature. An optical bandgap of 1.4 eV was achieved for the film deposited at 400°C, which demonstrated a Hall mobility of 3.95 cm2/V-s and a carrier concentration of 7.48 × 1016 cm-3. Cu3BiS3 films deposited at 375 and 400°C were implemented into superstrate solar cell structures (glass/ITO/n-CdS/p-Cu3BiS3/Al).
关键词： p-Cu3BiS3,optical band gap,thermal co-evaporation,thin film solar cell,absorber layer
更新于2025-09-12 10:27:22
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SERS-Active Substrates Nanoengineering Based on e-Beam Evaporated Self-Assembled Silver Films
摘要： Surface-enhanced Raman spectroscopy (SERS) has been intensely studied as a possible solution in the fields of analytical chemistry and biosensorics for decades. Substantial research has been devoted to engineering signal enhanced SERS-active substrates based on semi-continuous nanostructured silver and gold films, or agglomerates of micro- and nanoparticles in solution. Herein, we demonstrate the high-amplitude spectra of myoglobin precipitated out of ultra-low concentration solutions (below 10 μg/mL) using e-beam evaporated continuous self-assembled silver films. We observe up to 105 times Raman signal amplification with purposefully designed SERS-active substrates in comparison with the control samples. SERS-active substrates are obtained by electron beam evaporation of silver thin films with well controlled nanostructured surface morphology. The characteristic dimensions of the morphology elements vary in the range from several to tens of nanometers. Using optical confocal microscopy we demonstrate that proteins form a conformation on the surface of the self-assembled silver film, which results in an effective enhancement of giant Raman scattering signal. We investigate the various SERS substrates surface morphologies by means of atomic force microscopy (AFM) in combination with deep data analysis with Gwyddion software and a number of machine learning techniques. Based on these results, we identify the most significant film surface morphology patterns and evaporation recipe parameters to obtain the highest amplitude SERS spectra. Moreover, we demonstrate the possibility of automated selection of suitable morphological parameters to obtain the high-amplitude spectra. The developed AFM data auto-analysis procedures are used for smart optimization of SERS-active substrates nanoengineering processes.
关键词： metal film,neural networks,myoglobin,SERS substrate,e-beam evaporation
更新于2025-09-12 10:27:22
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Structural, optical, optoelectrical and photovoltaic properties of the thermally evaporated Sb2Se3 thin films
摘要： Production of inexpensive and promising light-absorbing materials is very important in photovoltaic device applications. In this study, we investigate the preparation of good-quality antimony selenide (Sb2Se3) thin films via thermal evaporation procedure with different thicknesses (241, 315, 387 and 429 nm). The analysis of the X-ray diffraction examination of the Sb2Se3 thin films demonstrates that the as-deposited Sb2Se3 thin films are polycrystalline with a single-phase orthorhombic structure. The elemental composition analysis of the evaporated Sb2Se3 thin film established that the as-deposited film has near stoichiometric composition of the compound. The linear optical results of the Sb2Se3 thin films revealed that the films show optical direct transitions and optical energy gaps in the range 1.12–1.05. The optoelectrical parameters of the Sb2Se3 thin films (ratio of the charge carrier concentrations to the effective mass N/m*, optical electronegativity ξopt and the lattice dielectric constant, εL) were estimated. The analysis of nonlinear optical parameters of the Sb2Se3 thin films reveals the increase of the film thickness combined with increase in the nonlinear refractive index. The Al/n-Si/Sb2Se3/Ag heterojunction was produced by the thermal evaporation technique. The photovoltaic constants of the Al/n-Si/Sb2Se3/Ag heterojunction were estimated from the J–V curve and demonstrate a solar efficiency of 4.03%.
关键词： Structural properties,Optoelectrical properties,Photovoltaic properties,Sb2Se3 thin films,Optical properties,Thermal evaporation
更新于2025-09-12 10:27:22
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Applications of Laser Ablation - Thin Film Deposition, Nanomaterial Synthesis and Surface Modification || Concurrent Multi-Target Laser Ablation for Making Nano-Composite Films
摘要： New method of using laser ablation for film deposition that can be called as concurrent multi-beam multi-target matrix-assisted pulsed laser evaporation and pulsed laser deposition (MBMT-MAPLE/PLD) is described. Practical MBMT-MAPLE/PLD system built at Dillard University has three separate laser beams, three targets and the remotely controlled plume overlapping mechanism that provides even mixing of the target materials during their deposition on the substrate. The system accommodates MAPLE targets in the form of polymer solutions frozen with flowing liquid nitrogen. The feasibility of the method was demonstrated when it was used for making polymer nano-composite films with two inorganic additives: upconversion fluorescent phosphor NaYF4:Yb3+, Er3+ and aluminum-doped ZnO (AZO). Three laser beams, an infrared 1064-nm beam for the MAPLE and two 532-nm beams for the PLD targets, were concurrently used in the process. The fabricated nano-composite films were characterized using X-ray diffraction, scanning electron microscopy (SEM), optical fluorescent spectroscopy, and the measurement of the quantum efficiency (QE) of the upconversion fluorescence. The size of the inorganic nanoparticles varied in the range 10–200 nm. The AZO additive increased QE by 1.6 times. The conclusion was made on the feasibility of MBMT-MAPLE/PLD method for making multi-component nano-composite films for various applications.
关键词： matrix-assisted pulsed laser evaporation,polymer nano-composite films,pulsed laser deposition,laser ablation
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Karbala City, Iraq (27–28 March 2019)] THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Structure, morphology and optical properties of thermally evaporated Cu2S thin films annealed at different temperatures
摘要： In the present work the preparation of Cu2S alloy was done throughout mixing the sulphur and copper elements according to the proper atomic weight and then put in an evacuated quartz ampoule which then sealed and heated at 1273 K for five hours and left to cool. Thin films from Cu2S powder thicknesses of ~300nm were prepared by thermal evaporation technique on a glass substrate and under vacuum of 10-5 mbar with rate of deposition 25nm/sec. The prepared thin films subjected to heat treatment at different temperatures(300, 373 , 473 and 573 K)for half an hour. The structures of Cu2S powder and films have been studied by X–ray diffraction technique. The result reveals that the prepared alloy has cubic structure and coincides with slandered cards while the prepared thin films have amorphous structure. The optical measurement shows that the Cu2S films have direct and indirect energy gap energy gap (Eg opt) for allowed transition. The energy gap (Eg opt) increases slightly with the increase annealing temperature and retune to increase with further increases of annealing temperature. The energy gap (Eg opt) increases from 2.55 to 2.6 eV and then decreases. The transmittance and optical constants such as refractive index (n), extinction coefficient (k) and dielectric constant (εr, εi) have been calculated. The optical constants decrease in the first and then return to increase with annealing temperature.
关键词： Cu2S thin films,optical properties,structural morphology,thermal evaporation,annealing temperature
更新于2025-09-11 14:15:04
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Vapor-phase synthesis of bimetallic plasmonic nanoparticles
摘要： Regulating the nanostructure of composite nanoparticles is essential for making them suitable for various applications. In general, the chemical reduction method is employed for the preparation of metal nanoparticles in the liquid phase. However, complicated techniques are required to control the nanostructure during particle synthesis. The evaporation/condensation method is used for synthesizing nanoparticles in the vapor-phase. Although this method produces impurity-free particles without aggregation, very few studies have been carried out on the synthesis of composite particles in the vapor-phase. In this study, we synthesized composite nanoparticles in the vapor-phase by using the evaporation/condensation method. The results showed that bimetallic nanoparticles are produced by the evaporation/condensation method. Moreover, it was indicated that the nanostructure of the synthesized nanoparticles is influenced by the order of the electric furnace with different temperature.
关键词： nanomaterial,Plasmonic,nanoparticle synthesis in vapor phase,nanostructure,evaporation/condensation method
更新于2025-09-11 14:15:04
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Single Source Thermal Evaporation of Two-dimensional Perovskite Thin Films for Photovoltaic Applications
摘要： Hybrid two-dimensional (2D) halide perovskites has been widely studied due to its potential application for high performance perovskite solar cells. Understanding the relationship between microstructural and opto-electronic properties is very important for fabricating high-performance 2D perovskite solar cell. In this work, the effect of solvent annealing on grain growth was investigated to enhance the efficiency of photovoltaic devices with 2D perovskite films based on (BA)2(MA)3pb4i13 prepared by single-source thermal evaporation. Results show that solvent annealing with the introduction of solvent vapor can effectively enhance the crystallization of the (BA)2(MA)3pb4i13 thin films and produce denser, larger-crystal grains. The thin films also display a favorable band gap of 1.896 eV, which benefits for increasing the charge-diffusion lengths. The solvent-annealed (BA)2(MA)3pb4i13 thin-film solar cell prepared by single-source thermal evaporation shows an efficiency range of 2.54–4.67%. Thus, the proposed method can be used to prepare efficient large-area 2D perovskite solar cells.
关键词： solvent annealing,thermal evaporation,two-dimensional perovskite,photovoltaic applications,grain growth
更新于2025-09-11 14:15:04
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Temperature Profile, Bead Geometry, and Elemental Evaporation in Laser Powder Bed Fusion Additive Manufacturing Process
摘要： Powder bed fusion processes have been a focus of research in recent years. Computational models of this process have been extensively investigated. In most cases, the distribution of heat intensity over the powder bed during the laser–powder interaction is assumed to follow a Gaussian beam pattern. However, the heat distribution over the surface is a complicated process that depends on several factors such as beam quality factor, laser wavelength, etc. and must be considered to present the laser–material interaction in a way that represents the actual beam. This work presents a process in which a non-Gaussian laser beam model is used to model the temperature pro?le, bead geometry, and elemental evaporation in the powder bed process. The results are compared against those of a Gaussian beam model and also an experiment using Inconel 718 alloy. The model offers good predictions of the temperature, bead shape, and concentration of alloying elements.
关键词： Additive manufacturing,Temperature profile,Powder bed fusion,Laser powder bed fusion,Bead geometry,Non-Gaussian beam,Elemental evaporation
更新于2025-09-11 14:15:04
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Multistage Degradation Mechanisms in Cu(In, Ga)Se2 Photovoltaic Modules Prepared by Co-Evaporation: Toward High Performances and Enhanced Stability
摘要： This study compared the stability and durability of copper indium gallium selenide (CIGS)-type solar cells prepared using one-step and three-step co-evaporation methods by investigating the causes of degradation in each layer in detail. Measurements recorded using a solar simulator showed that the sample prepared using the three-step method had better device performance owing to the large-grained structure of the CIGS absorber layer, which reduced the carrier recombination. Focusing on the discrepancy in grain size, multifarious degradation tests were conducted according to the IEC 61646 standard to evaluate the stability of the cells under harsh environments such as high humidity (85 %), high temperature (85 ℃), and mechanical load. Damp heat (85 %/85 ℃) did not affect the CIGS resistivities in either sample, whereas all the aluminum-doped zinc oxide layers degraded, as determined by confirming the chemisorbed oxygen by exposure to a hot, humid environment. After 200 thermal cycles, the CIGS layers in both samples were mainly degraded while there were no changes in the resistivities of the AZO layer in either sample. The thermal cycling test highlights that the initial resistivities of the one-step sample showed a decisive change before and after thermal cycling compared to the three-step sample. This change might be caused carriers being scattered at the grain boundaries. Although there were no big differences in the FT-IR spectra before and after thermal cycling, both XRD and XPS results confirmed that not only copper indium sulfide selenium elements of secondary phase were newly observed by sulfide diffusion from the CdS layer, but also that each element (Cu, In, Ga, and Se) was slightly oxidized by the rapid temperature variation from ?45 ℃ to 85 ℃. These results prove that the three-step co-evaporation method can produce cells with much higher stability and durability, even when operated under high humidity and temperature conditions.
关键词： Degradation mechanism,Copper indium gallium selenide,Co-evaporation,Grain size,Stability,Aluminum-doped zinc oxide
更新于2025-09-11 14:15:04