Search Results (253)

BaBiO₃ has recently gained significant research attention as a parent material for an interesting family of alloyed compositions with multiple technological applications. In order to grow a variety of structures, a versatile deposition tool such as molecular beam epitaxy must be employed. In this work, the molecular beam epitaxy growth of BaBiO₃ on SrTiO₃(001) and MgO(001) substrates is studied. When grown by molecular beam epitaxy on SrTiO₃(001) or MgO(001) substrates, BaBiO₃ is known to have two competing orientations, namely (001) and (011). Characterization of the thin film is carried out by X-ray diffraction, X-ray reflectivity, atomic force microscopy, Rutherford backscattering, and transmission electron microscopy. Pathways to block the growth of BaBiO₃(011) and to grow only the technologically relevant BaBiO₃(001) are described for both substrates. An understanding of the enabling mechanism of the co-growth is established from an epitaxial point of view. This can be beneficially utilized for the growth of different compositions in the BaBiO₃ material family in a more controlled manner. Full article

This study examines the surface-dependent formation of interpolymer complexes (IPCs) by the layer-by-layer (LBL) deposition method. The materials used in this analysis are poly(acrylic acid) (PAA) combined with cellulose ethers, namely methyl cellulose (MC), hydroxypropyl cellulose (HPC), and hydroxyethyl cellulose (HEC), and poloxamers PX188 and PX407. PMMA, PS, and glass surfaces have been used to study the influence of hydrophobicity and hydrophilicity on IPC growth and its properties. Through contact angle measurements, PMMA and PS were found to be hydrophobic and glass hydrophilic. It was revealed by gravimetric analysis that IPC films reveal the highest growth on PMMA substrates, followed by PS and glass. Both the molecular weight of HEC and the hydrophobicity of the surface considerably affected the growth. Hydrogen-bonded complexation was evident by means of FTIR spectroscopy, while changes in some characteristic absorption bands demonstrated the extent of interactions between polymers. Scanning electron microscopy showed that variations in the microstructure of surfaces occur; PAA-MC and poloxamer complex layers were well organized on hydrophobic substrates. Thus, the experimental results showed surface properties, especially hydrophobicity, to be important for IPC growth and structure. These findings contribute to the understanding of IPC behavior on different substrates, thus giving insights into applications in drug delivery, coatings, and functional films. Full article

S-shaped dinaphtho[2,1-b:2′,1′-f]thieno[3,2-b]thiophene (S-DNTT) molecules have shown promise for applications in organic electronic devices, though their molecular characteristics are not fully understood yet. In this study, we first revealed the material characteristics of S-DNTT-10 by vibrational dynamics using Raman spectroscopy and density functional theory (DFT) simulations, employing the B3LYP functional method and the 6-311G (d, p) basis set. The molecular vibrations identified included C–H bending in alkyl chains and the deformation of S-shaped thiophene rings. In addition, surface-enhanced Raman scattering (SERS) with 785 nm incident light was applied to thermally deposited 25 nm S-DNTT-10 thin films with gold (Au) nanostructures. It showed enhanced Raman signals from the lower S-DNTT-10 layers. The findings significantly contribute to the knowledge of S-DNTT-10 molecular properties and also contribute insights into using this material into organic electronic devices in the future. Full article

The structural and electronic properties at organic/organic interfaces determine the functionality of organic electronics. Here, we investigated the structural and electronic properties at interfaces between methyl-substituted dicyanovinyl-quinquethiophenes (DCV5T-Me₂) and other electron acceptor molecules, namely fullerene (C₆₀) and tetracyanoquinodimethane (TCNQ), by using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS). Upon adsorption on Au(111), DCV5T-Me₂ molecules self-assemble into compact islands at sub-monolayer coverage through hydrogen bonding and electrostatic interactions. A similar bonding configuration dominates in the second layer of a bilayer film, where DCV5T-Me₂ possesses higher-lying LUMO (lowest unoccupied molecular orbital) and LUMO+1 in energy due to a decoupling effect. The co-deposition of DCV5T-Me₂ and C₆₀ does not result in ordered hybrid assemblies at the sub-monolayer coverage on Au(111). On the other hand, C₆₀ molecules can self-assemble into ordered islands on top of the DCV5T-Me₂ monolayer. The dI/dV spectra reveal that the LUMO of decoupled C₆₀ is 400 mV lower in energy than the LUMO of decoupled DCV5T-Me₂. This energy difference facilitates electron transfer from DCV5T-Me₂ to C₆₀. The co-deposition of DCV5T-Me₂ and TCNQ leads to the formation of hybrid nanostructures. A tip-induced electric field can manipulate the charging and discharging of TCNQ by surrounding DCV5T-Me₂, manifested as sharp peaks and dips in dI/dV spectra recorded over TCNQ. Full article

Self-assembled monolayers (SAMs) have gained significant attention as an interfacial engineering strategy for perovskite solar cells (PSCs) due to their efficient charge transport ability and work function tunability. While solution-based methods such as dip-coating and spin-coating are widely used for SAM deposition, challenges such as non-uniform coverage, solvent contamination, and limited control over molecular orientation hinder their scalability and reproducibility. In contrast, vacuum deposition techniques, including thermal evaporation, overcome these limitations by enabling the formation of highly uniform materials with precise control over thickness and molecular arrangement. Importantly, the chemical interactions between SAM materials and perovskite layers, including coordination bonding with Pb²⁺ ions, play an important role in passivating surface defects, modulating energy levels, and promoting uniform perovskite crystallization. These interactions not only enhance wettability but also improve the overall quality and stability of perovskite films. This review highlights the advantages of vacuum-deposited SAMs, promoting strong chemical interactions with perovskite layers and improving interfacial properties critical for scalable applications. Full article

3D-printing enables the fabrication of membranes with desired shapes and geometrical parameters. In this study, a membrane for pressure-driven processes was manufactured in a single step using the fused deposition modeling (FDM) technique. The membrane was produced from a mixture of polylactic acid (PLA) with sucrose as a pore-forming agent. Sucrose was removed from the final membrane by washing it with water. The membrane consists of three layers, and this sandwich-like structure ensures its mechanical stability. The material obtained was characterized using SEM and AFM imaging, as well as nitrogen adsorption-desorption and contact angle measurements. The porosity of each layer of the membrane is due to a loose region, which is coated on both sides with a dense film formed during printing. The pores responsible for rejection capability can be found in grooves between the polymer stripes in the dense layer. The membrane exhibits a water permeability of 64 L m⁻²h⁻¹bar⁻¹, with a molecular weight cut-off of 69 kDa. The PLA membrane can be used for polyphenol concentration, demonstrating a permeability of 2–3.4 L m⁻²h⁻¹bar⁻¹ and a selectivity towards these compounds of 78–98% at 0.5 bar, with a flux decline ratio of up to 50%. Full article

LiNbO₃ plays a significant role in modern integrated photonics because of its unique properties. One of the challenges in modern integrated photonics is reducing chip production cost. Today, the most widespread yet expensive method to fabricate thin films of LiNbO₃ is the smart cut method. The high production cost of smart-cut chips is caused by the use of expensive equipment for helium implantation. A prospective method to reduce the cost of photonic integrated circuits is to use sputtered thin films of lithium niobite, since sputtering technology does not require helium implantation equipment. The purpose of this review is to assess the feasibility of applying sputtered LiNbO₃ thin films in integrated photonics. This work compares sputtered LiNbO₃ thin films and those fabricated by widespread methods, including the smart cut method, liquid-phase epitaxy, chemical vapor deposition, pulsed laser deposition, and molecular-beam epitaxy. Full article

Large organic molecules and metal complexes are promising candidates for organic electronics, optoelectronics, and spintronics, with interfaces to metals being critical. Clean preparation in ultra-high vacuum (UHV) is ideal, but many systems are fragile and cannot be thermally sublimed. This study details the preparation of thin films of the metallacrown Cu(II)[12-MC_Cu(II)N(Shi)-4] (short: CuCu4) from the liquid phase using electrospray injection (ESI) and, in particular, liquid injection (LI). Both methods produce films with intact CuCu4 complexes, but they differ in the amount of co-adsorbed solvent molecules. Enhancements using an argon stream perpendicular to the molecular beam significantly reduce these contaminants. An additional effect occurs due to the counterions (HNEt₃)₂ of CuCu4. They are co-deposited by LI, but not by ESI. The advantages and limitations of the LI method are discussed in detail. The CuCu4 films prepared by different methods were analyzed with infrared (IR) spectroscopy, ultraviolet and X-ray photoelectron spectroscopy (UPS, XPS), and scanning tunneling microscopy (STM). For thicker films, ex situ and in situ prepared CuCu4 films to exhibit similar properties, but for studying interface effects or ultrathin films, in situ preparation is necessary. Full article

This study focuses on the deposition of fullerene (C₆₀) as thin film on glass substrate by ultrasonic chemical bath deposition (UCBD) processing, under ambient temperature. Highly effective results were obtained from the films based on the solution of C₆₀ dissolved in toluene mixed with 2-methoxyethanol. The obtained films were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). The XRD examination of the thin films reveals the presence of the C₆₀ cubic phase compared to the powder reference. The molecular structure obtained by Rietveld refinement shows no bonding between the molecules in C₆₀ powder, while in the deposed thin film the bonding is established. The molecules are bonded between them by pentagons of the right and left molecule. Each four neighbor molecules bond between them and they are all able to geometrically tie to the neighboring molecules under a crystalline FCC structure. The Sherrer and W-H methods were used to investigate microstructural parameters. The lattice parameter and the crystallite size show the same variation tendency. The average lattice parameter for the powder and the deposed films C₆₀-3h, C₆₀-5h, and C₆₀-8h is 14.0652, 14.1901, 14.0529, and 14.1848 Å, respectively, and the crystallite size calculated by the Sherrer method is 37.51, 38.98, 34.35, and 41.54 nm, respectively, as well. The IR spectrum indicated the presence of chemical π bonds (c=c) that are very suitable for enhancing the electronic properties of the material, and SEM analysis illustrated a dense, homogeneous without pinhole structures in the film morphology. Moreover, EDS emphasizes the presence of high carbon concentration and fewer stranger atoms. As a result, despite the UCBD technique being old and not very often applied in the field of organic materials, it is still a cost effective and good alternative method for organic thin film deposition. Full article

Lithium niobate (LiNbO₃) has remarkable ferroelectric properties, and its unique crystal structure allows it to undergo significant spontaneous polarization. Lithium niobate plays an important role in the fields of electro-optic modulation, sensing and acoustics due to its excellent electro-optic and piezoelectric properties. Thin-film LiNbO₃ (TFLN) has attracted much attention due to its unique physical properties, stable properties and easy processing. This review introduces several main preparation methods for TFLN, including chemical vapor deposition (CVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD), magnetron sputtering and Smartcut technology. The development of TFLN devices, especially the recent research on sensors, memories, optical waveguides and EO modulators, is introduced. With the continuous advancement of manufacturing technology and integration technology, TFLN devices are expected to occupy a more important position in future photonic integrated circuits. Full article

Epitaxial growth can be used to guide the controllable growth of one metal on the surface of another substrate by matching the interface lattice, thus improving the dendrite tendency of metal growth. The atomic arrangement of the Cu (111) crystal plane of the FCC structure is similar to that of the Zn (0002) crystal plane of the HCP structure, which is theoretically expected to promote the heterogeneous epitaxial nucleation growth of metal zinc under low strain. In this paper, the molecular dynamics method is used to simulate the atomic process of zinc film growth on the Cu (111) surface. It is found that the behavior of zinc-adsorbed atoms on the substrate surface conforms to the epitaxial growth mode. The close-packed structure grown along the (0002) direction of the layered clusters is tiled on the Cu (111) surface, forming a highly ordered low-lattice-mismatch interface. When a large area of layered zinc clusters cover the substrate, the growth mode will change from heteroepitaxial growth to homoepitaxial growth of Zn atoms on the zinc film, forming a lamellar distribution composed of FCC and HCP structure grains. Polycrystalline zinc film with a planar structure with a (0002) surface preferred a crystal plane. The increase in incident energy is helpful in improving the quality of zinc films, while the deposition rate, corresponding to the deposition temperature and electrolyte ion concentration, has no significant effect on the surface morphology and crystal structure of single metal films. In summary, the atomic arrangement of the Cu (111) surface has a strong guiding effect on the atomic ordered arrangement in the zinc film crystal, which is suitable for the epitaxial deposition of the substrate to induce the ordered growth of the Zn (0002) crystal plane. Full article

The surfaces of beech wood samples were treated with polyethylenimine (PEI) solutions at three different concentrations—0.5%, 1% and 2%—and two molecular weights—low molecular weight (LMW) and high molecular weight (HMW). The effects of PEI surface treatment of wood were characterized by FT-IR spectroscopy, the penetration depth of PEI (EPI fluorescence spectroscopy), the bonding position of PEI (by SEM), the wetting and surface energy, and the water uptake. After PEI treatment, the samples were coated with a water-based transparent acrylic coating (WTAC). The dry film thickness, the penetration depth of the coating, the adhesion strength and the surface roughness of the coated wood surface were evaluated. EPI fluorescence and SEM micrographs showed that PEI HMW chains were deposited on the surface, in contrast to PEI LMW, which penetrates deeper into layers of the wood cells. Treatment with a 1% PEI HMW solution resulted in a 72% reduction in water uptake of the wood (compared to untreated samples after 5 min of applying water droplets to the surface) and a 23.2% reduction in surface energy (compared to untreated samples) while maintaining the adhesion strength of the applied WTAC. The lower water uptake of the treated wood samples reduced the roughness of the coated surface, which is particularly important when the wood surface is finished with water-based coatings. Full article

Kesterite-based semiconductors, particularly copper–zinc–tin–sulfide (CZTS), have garnered considerable attention as potential absorber layers in thin-film solar cells because of their abundance, nontoxicity, and cost-effectiveness. In this study, we explored the synthesis of Ag-alloyed CZTS (ACZTS) materials via the sol–gel method and deposited them on a transparent fluorine-doped tin oxide (FTO) back electrode. A key challenge is the selection and manipulation of metal–salt precursors, with a particular focus on the oxidation states of copper (Cu) and tin (Sn) ions. Two distinct protocols, varying the oxidation states of the Cu and Sn ions, were employed to synthesize the ACZTS materials. The transfer from the solution to the precursor film was analyzed, followed by annealing at different temperatures under a sulfur atmosphere to investigate the behavior and growth of these materials during the final stage of annealing. Our results show that the precursor transformation from solution to film is highly sensitive to the oxidation states of these metal ions, significantly influencing the chemical reactions during sol–gel synthesis and subsequent annealing. Furthermore, the formation pathway of the kesterite phase at elevated temperatures differs between the two protocols. Structural, morphological, and optical properties were characterized via X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM). Our findings highlight the critical role of the Cu and Sn oxidation states in the formation of high-quality kesterite materials. Additionally, we studied a novel approach for controlling the synthesis and phase evolution of kesterite materials via molecular inks, which could provide new opportunities for enhancing the efficiency of thin-film solar cells. Full article

Poly(butyl cyanoacrylate) (PBCA) nanoparticles have numerous applications, including drug and gene delivery, molecular imaging, and cancer therapy. To uncover the molecular mechanisms underlying their interactions with cell membranes, we utilized a Langmuir monolayer as a model membrane system. This approach enabled us to investigate the processes of penetration and reorganization of PBCA nanoparticles when deposited in a phospholipid monolayer subphase. Atomic force microscopy (AFM) was employed to visualize Langmuir–Blodgett (LB) films of these nanoparticles. Additionally, we examined the state of a monolayer of Pluronic F68, a stabilizer of PBCA nanoparticles in suspension, by measuring the changes in relative surface area and surface potential over time in the barostatic regime following PBCA suspension spreading. Based on these findings, we propose a molecular mechanism for nanoparticle reorganization at the air–water interface. Full article

To demonstrate the feasibility of obtaining low-molecular-weight organic films (below 200 Da) using non-solvent PVD processes, glucose layers were produced via pulsed laser deposition (PLD) and pulsed electron beam deposition (PED) methods. Glucose was chosen due to its fundamental role in various biological processes, and because this low-molecular-weight compound is a solid at room temperature, which is required for both techniques. The physical and chemical structures of the deposited glucose layers were characterized by optical, scanning electron, and atomic force microscopy, as well as by X-ray diffraction, X-ray photoelectron, and infrared spectroscopy. Both PLD and PED methods resulted in glucose layers with good chemical structure preservation (with minor oxidation observed in PED) while yielding films with distinct physical properties. This opens up the possibility of tailoring organic layers with specific characteristics depending on the application, by choosing the deposition method. Full article