Film Surface Research Articles

Study on the painting methods, amount and thermal properties of waterborne acrylic paint on bamboo-laminated lumber for furniture

In order to understand the finishing effect of Waterborne Acrylic Paint under different painting methods and amount, bamboo-laminated lumber for furniture was coated with waterborne acrylic paint, then the effects of different painting methods and amount on the drying rate, smoothness, hardness, adhesion and wear resistance of the paint film were investigated. Further, the mechanism of film formation was described by thermal property analysis using thermogravimetry and differential scanning calorimeter. The results show that different painting methods have little effect on film properties, the drying time of primer and topcoat are not affected by them, which is 8/8.5 min for primer surface/solid and 6.5/7 min for topcoats. The film surface hardness and adhesion can reach B and 0 grade, the best wear resistance of the film is 51.24 mg·100 r−1 when using one-layer primer one-layer topcoat. Different coating amount has great influence on film properties, the drying speed of the film increases with the increase of the painting amount. The film properties reach the best when the painting amount is 80 g/m2, while too little painting amount leads to the decrease of hardness, and too much leads to the wear resistance weaken. Thermal analysis of the primer and topcoat show that water decomposition occurs at 100 ℃ and thermal decomposition of organic components occur at 350 ℃. Topcoats have better thermal stability than primers higher than that of topcoat, the topcoat displayed better thermal stability than the primer.

Wet–dry cycles cause nucleic acid monomers to polymerize into long chains

The key first step in the oligomerization of monomers is to find an initiator, which is usually done by thermolysis or photolysis. We present a markedly different approach that initiates acid-catalyzed polymerization at the surface of water films or water droplets, which is the reactive phase during a wet–dry cycle in freshwater hot springs associated with subaerial volcanic landmasses. We apply this method to the oligomerization of different nucleic acids, a topic relevant to how it might be possible to go from simple nucleic acid monomers to long-chain polymers, a key step in forming the building blocks of life. It has long been known that dehydration at elevated temperatures can drive the synthesis of ester and peptide bonds, but this reaction has typically been carried out by incubating dry monomers at elevated temperatures. We report that single or multiple cycles of wetting and drying link mononucleotides by forming phosphodiester bonds. Mass spectrometric analysis reveals uridine monophosphate oligomers up to 53 nucleotides, with an abundance of 35 and 43 nt in length. Long-chain oligomers are also observed for thymidine monophosphate, adenosine monophosphate, and deoxyadenosine monophosphate after exposure to a few wet–dry cycles. Nanopore sequencing confirms that long linear chains are formed. Enzyme digestion shows that the linkage is the phosphodiester bond, which is further confirmed by 31 P NMR and Fourier transform infrared spectroscopy. This suggests that nucleic acid oligomers were likely to be present on early Earth in a steady state of synthesis and hydrolysis.

Effect of adding ionic liquid into polydimethylsiloxane on the output performance of triboelectric nanogenerator

Abstract Adding 1-butyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide (BMIM-TFSI), an ionic liquid, to polydimethylsiloxane (PDMS) films significantly enhances the output of triboelectric nanogenerators (TENGs). In a TENG using contact and separation between the composite film and an aluminum (Al) plate, incorporating 0.1 vol.% of BMIM-TFSI more than doubled the output voltage was achieved compared to a pure PDMS film. To understand the cause of this improvement, composition analysis around the surface of the composite polymer film was conducted before and after tapping. We found that BMIM-TFSI molecules segregated around the surface after tapping. It is considered that the polarization of the BMIM-TFSI molecules enhances the output performance of TENGs by superimposing on the surface charges generated at the PDMS/Al interface.

Synthesis and characterization of the chitosan-xanthan-graphene oxide film for bone regeneration using advanced cell therapy

The present study aimed to synthesize and characterize polymer films at different graphene oxide (GO) concentrations for use in advanced cell therapy. Chitosan-xanthan (CX) films were prepared and combined with GO and then assigned to the following groups: G1 – CX; G2 – CX GO 0.5%; G3 – CX GO 1.0%; and G4 – CX GO 1.5%. The films were analyzed for their structural, mechanical, and biological properties by Raman and Fourier-Transform Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Confocal Laser Scanning Microscopy (surface roughness measurement), Tensile Strength, and in vitro Bioactivity assay. Tensile strength and surface roughness data were analyzed by one-way analysis of variance (ANOVA), followed by Tukey’s test (α = 0.05). FTIR spectroscopy showed the presence of amide I and II bands (characteristic of chitosan) and carboxyl group (characteristic of xanthan). CO bands characteristic of GO were observed in groups containing these particles. Raman spectroscopy revealed D and G bands in the GO-containing groups. Film surface morphology exhibited a homogeneous, compact, and pore-free surface. The CX group had higher tensile strength (5.89 ± 1.62 KPa) ( p < 0.05). No statistically significant difference was observed in the other GO-containing groups ( p > 0.05). The films induced the deposition of apatite crystals on their surfaces, exhibiting activity under biomineralization conditions. Graphene oxide added into chitosan-xanthan films enhanced surface roughness and bioactivity but decreased tensile strength. The synthesized CXGO films are promising for advanced cell therapy because of their physicochemical, morphological, and mechanical properties, which seem ideal for tissue regeneration.

Plasmon-enhanced Brillouin light scattering spectroscopy for magnetic systems: Theoretical model

Brillouin light scattering (BLS) spectroscopy is an effective method for detecting spin waves in magnetic thin films and nanostructures. While it provides extensive insight into the properties of spin waves, BLS spectroscopy is impeded in many practical cases by the limited range of detectable spin wave wave numbers and its low sensitivity. Here we present a generalized theoretical model describing plasmon-enhanced BLS spectroscopy. Three types of plasmonic nanoparticles in the shape of an ellipsoid of rotation are considered: a single plasmon resonator, a sandwiched plasmonic structure in which two nanoparticles are separated by a dielectric spacer, and an ensemble of metallic nanoparticles on the surface of a magnetic film. The effective susceptibilities for the plasmonic systems at the surface of the magnetic film are calculated using the electrodynamic Green's function method, and the enhancement coefficient is defined. It is analytically shown that the ratio of the plasmon resonator height to its radius plays a key role in the development of plasmon-enhanced BLS spectroscopy. The developed model serves as a basis for the numerical engineering of the optimized plasmon nanoparticle morphology for BLS enhancement. Published by the American Physical Society 2024

Surface Depth Analysis of Chemical Changes in Random Copolymer Thin Films Composed of Hydrophilic and Hydrophobic Silicon-Based Monomers Induced by Plasma Treatment as Studied by Hard X-ray Photoelectron Spectroscopy and Neutron Reflectivity Measurements.

In this study, a silicon-based copolymer, poly(tris(trimethylsiloxy)-3-methacryloxypropylsilane)-co-poly(N,N-dimethyl acrylamide), thin film was subjected to plasma surface treatment to make its surface hydrophilic (biocompatible). Neutron reflectivity (NR) measurement of the plasma-treated thin film showed a decrease in the film thickness (etching width: ∼20 nm) and an increase in the scattering length density (SLD) near the surface (∼15 nm). The region with a considerably high SLD adsorbed water (D2O) from its saturated vapor, indicating its superior surface hydrophilicity. Nevertheless of the hydrophilicity, the swelling of the thin film was suppressed. Hard X-ray photoelectron spectroscopy (HAXPES) performed at various takeoff angles revealed that the thin-film surface (∼20 nm depth) underwent extensive oxidation. NR and HAXPES analysis quantitatively yielded the depth profiling of elemental compositions in a few tens of nm scale. Si oxidation and hydrogen elimination (probably CH3 groups) in the vicinity of the surface region increased the SLD and decreased the hydrophobicity. A combination of Soft X-ray photoelectron spectroscopy and NR measurements revealed the surface chemical composition and mass density. It was considered that the surface near the film was chemically composed close to SiO2, forming a gel-like (three-dimensional network) structure that is hydrophilic and suppresses swelling due to moisture, indicating it can be expected to maintain stable hydrophilicity on the film surface.

Lubrication Characteristics of a Warhead-Type Irregular Symmetric Texture on the Stator Rubber Surfaces of Screw Pumps

A theoretical model for the micro-texture on the inner wall of the stator rubber in screw pumps was developed. The finite element analysis method was employed. The pressure and streamline distributions for warhead-type, concentric circle-type, and multilayer rectangular-type textured surfaces were calculated. The effects of textured morphology, groove depth, groove width, and other parameters on the lubrication field were systematically investigated and analyzed. A nanosecond laser was employed to process the textured rubber surface of the stator in the screw pump. Subsequently, a micro-texture friction performance test was conducted on the rubber surface of the stator in actual complex well fluids from shale oil wells. Given the results of the simulation analysis and experimental tests, the lubrication characteristics of textured rubber surfaces with varying texture morphologies, rotational speeds, and mating loads were revealed. Furthermore, it indicated that the irregular symmetric warhead-type micro-texture exhibited excellent dynamic pressure lubrication performance compared with concentric circle-type and multilayer rectangular-type textures. The irregular symmetry enhanced the dynamic pressure lubrication effect, enhanced the additional net load-bearing capacity of the oil film surface, and reduced friction. As the groove depth increased, the volume and number of vortices within the groove also increased. The fluid kinetic energy was transformed into vortex energy, leading to a reduction in wall stress on the surface of the oil film, thereby affecting its bearing capacity. Initially, the maximum pressure on the wall surface of the oil film increased and then decreased. The optimal dynamic pressure lubrication effect was achieved with a warhead-type texture size of 3 mm, a groove width of 0.2 mm, and a groove depth of 0.1 mm. Well-designed texture morphology and depth parameters significantly enhanced the oil film-bearing capacity of the stator rubber surface, improving the dynamic pressure lubrication effect, and consequently extending the service life of the stator–rotor interface in the screw pump.

Tailoring Multifunctional Amine Salts Based on Anisole Liquid Soaking for Fabricating Efficient and Stable Perovskite Solar Cells.

The post-treatment based on spin-coating (SC) organic amine salts is commonly used for surface modification of perovskite films to eliminate defects. However, there is still a lack of systematic study and a unified understanding of the functions and mechanisms of different organic amine salts. The SC method is also not conducive to the industrialization of solar cells. In this work, we study three different organic amine salts, and a passivation strategy for perovskite films based on green anisole liquid soaking (ALS) has been developed. Phenylethylammonium iodide (PEAI), diethylamine hydroiodide (DEAI), and guanidine hydroiodide (GAI) organic amine salt passivators are selected to modify perovskite films, and their effect and working mechanism are also systematically estimated. It is found that PEAI passivates shallow-level defects on the surface of perovskite films, while DEAI incorporates into the perovskite lattice to suppress point defects, and GAI eliminates excess PbI2 residuals in perovskite films. These three organic-amine-salt-modified devices achieve enhanced power conversion efficiencies (PCE) of 21.82% (PEAI-ALS), 21.74% (DEAI-ALS), and 22.21% (GAI-ALS), which is much higher than that of the pristine device without treatment (19.95%). The PCE of the PEAI-ALS device retains nearly 94% of the initial efficiency after 1200 h in unpackaged conditions and about 40% ambient humidity, achieving the best stability performance. Particularly, the PEAI-ALS device has the best comprehensive performance in efficiency and stability. And PEAI is estimated by the SC method and ALS method, and it is found that the PEAI-ALS device achieves a higher PCE compared to the PEAI-SC device (21.51%). We believe that the post-treatment based on a combination of appropriate amine salts and ALS enables a universal approach for fabrication of perovskite solar cells with enhanced photovoltaic performance.

Production of Polyvinyl Alcohol/Amoxicillin – Chitosan/Collagen Hybrid Bilayer Membranes for Regeneration of Gingival Tissues

AbstractPeriodontal diseases, if untreated, can cause gum recession and tooth root exposure, resulting in infection and irreversible damage. Traditional treatments using autologous grafts are painful and often result in postoperative complications. Scaffolds offer a less invasive alternative, promoting cell proliferation and healing without additional surgery, thus enhancing comfort for patients and doctors. This study developed Chitosan (Chit)/Collagen (Col) film surfaces and drug‐loaded Polyvinyl Alcohol (PVA)/Amoxicillin (AMX) nanofibers using solvent casting and electrospinning methods, respectively. The surfaces are characterized by scanning electron microscopy (SEM), mechanical testing, Fourier Transform Infrared Spectroscopy (FTIR), and differential scanning calorimetry (DSC). Biocompatibility and antimicrobial properties are assessed using NIH/3T3 fibroblast cells and bacterial cultures. SEM images confirmed the structural integrity of AMX‐loaded 13% PVA nanofibers, while FTIR analysis validated the compositional integrity of PVA/AMX nanofibers and Chit/Col film hybrid surfaces. Cell studies showed over 90% viability for Chit/Col film + PVA/AMX nanofiber hybrid bilayer membranes, confirming their biocompatibility. The antimicrobial assessment indicated that the Chit/Col film + PVA/AMX (0.2%) nanofiber hybrid bilayer membrane exhibited superior efficacy against Streptococcus mutans. These findings suggest that this hybrid bilayer membrane can enhance cell growth, promote proliferation, and enable controlled drug release, offering significant promise for regeneration of gingival tissues.

Analysis of Water Film Distribution and Aerodynamic Performances of High-Speed Train Under Rainfall Environment

The current research on the aerodynamic performance of the train running in rainy weather is primarily concerned with the trajectory of the raindrops and the aerodynamic variation of trains caused by raindrops. In fact, water film will generate on the train body when raindrops hit the train, which interacts with the flow field around the train, and would probably affect the aerodynamic performance of the train. In this paper, based on shear stress transport (SST) k-w turbulence model and Euler-Lagrange discrete phase model, the aerodynamic calculation model of a high-speed train under rainfall environment is established. The LWF (Lagrangian wall film) is used to simulate the water film distribution of the high-speed train under different rainfall intensities, and the aerodynamic performance of the train are studied. The calculation results show that raindrops will gather on the train surface and form water film under rainfall environment. With the extension of rainfall time, the thickness and coverage range of water film expand, and the maximum thickness of water film can reach 4.95 mm under the working conditions in this paper. The average thickness of water film on the train body increases with the rainfall intensity. When the rainfall intensity increases from 100 mm/h to 500 mm/h, the average water film thickness will increase by 3.26 times. The velocity of water film in the streamlined area of head car is larger than that in other areas, and the maximum velocity is 22.14 m/s. Compared with the rainless environment condition, the skin friction coefficient of the high-speed train increases and the average value will increase by 10.74% for a rainfall intensity of 500 mm/h. The positive pressure and resistance coefficient of the head car increase with the rainfall intensity. This research proposes a methodology to systematically analyze the generation of water film on the train surface and its influence on the train aerodynamic performance; the analysis can provide more practical results and can serve as a reference basis for the design and development of high-speed trains.

Dual‐Site Anchors Enabling Vertical Molecular Orientation for Efficient All‐Perovskite Tandem Solar Cells

AbstractAll‐perovskite tandem solar cells (TSCs) are gaining increasing attention due to their potential to surpass the efficiency limit of single‐junction solar cells. However, as the bottom low‐bandgap subcells, tin‐lead (Sn‐Pb) perovskites suffer from severe nonradiative recombination at the interfaces due to their susceptibility to oxidation and poor crystalline morphology. Here a surface modifier 4‐(trifluoromethyl)benzhydrazide (TFH) is reported to construct a reductive chemical environment on the surface of perovskite films and protect them from water and oxygen erosion. TFH anchors onto the Sn‐Pb perovskites in a preferred vertical orientation through dual‐site binding, forming interface dipoles that facilitate charge extraction. The reductive hydrazine groups of TFH can effectively inhibit the oxidation of Sn2+ and I−, thereby reducing the defect density and energy disorder of Sn─Pb perovskites. Consequently, the TFH‐treated devices achieved a champion PCE of 22.88%, maintaining over 93% of the initial efficiency after continuous one‐sun illumination for 500 h. Combined with a 1.79 eV wide‐bandgap subcell, it has demonstrated a PCE of 28.17% in all‐perovskite TSCs.

Impact of submicron Nb3Sn stoichiometric surface defects on high-field superconducting radiofrequency cavity performance

Nb3Sn film coatings have the potential to drastically improve the accelerating performance of Nb superconducting radiofrequency (SRF) cavities in next-generation linear particle accelerators. Unfortunately, persistent Nb3Sn stoichiometric material defects formed during fabrication limit the cryogenic operating temperature and accelerating gradient by nucleating magnetic vortices that lead to premature cavity quenching. The SRF community currently lacks a predictive model that can explain the impact of chemical and morphological properties of Nb3Sn defects on vortex nucleation and maximum accelerating gradients. Both experimental and theoretical studies of the material and superconducting properties of the first 100 nm of Nb3Sn surfaces are complicated by significant variations in the volume distribution and topography of stoichiometric defects. This work contains a coordinated experimental study with supporting simulations to identify how the observed chemical composition and morphology of certain Sn-rich and Sn-deficient surface defects can impact the SRF performance. Nb3Sn films were prepared with varying degrees of stoichiometric defects, and the film surface morphologies were characterized. Both Sn-rich and Sn-deficient regions were identified in these samples. For Sn-rich defects, we focus on elemental Sn islands that are partially embedded into the Nb3Sn film. Using finite element simulations of the time-dependent Ginzburg-Landau equations, we estimate vortex nucleation field thresholds at Sn islands of varying size, geometry, and embedment. We find that these islands can lead to significant SRF performance degradation that could not have been predicted from the ensemble stoichiometry alone. For Sn-deficient Nb3Sn surfaces, we experimentally identify a periodic nanoscale surface corrugation that likely forms because of extensive Sn loss from the surface. Simulation results show that the surface corrugations contribute to the already substantial drop in the vortex nucleation field of Sn-deficient Nb3Sn surfaces. This work provides a systematic approach for future studies to further detail the relationship between experimental Nb3Sn growth conditions, stoichiometric defects, geometry, and vortex nucleation. These findings have technical implications that will help guide improvements to Nb3Sn fabrication procedures. Our outlined experiment-informed theoretical methods can assist future studies in making additional key insights about Nb3Sn stoichiometric defects that will help build the next generation of SRF cavities and support related superconducting materials development efforts. Published by the American Physical Society 2024

The Effect of Kappa Carrageenan Composition on the Characteristics of Chitosan-Kappa Carrageenan Hydrogel Film

Chitosan-Kappa Carrageenan (Chit-KC) hydrogel films have been made using a casting method with different compositions. This research aimed to investigate the effects of different compositions on the chemical, physical, and mechanical characteristics of the Chit-KC hydrogel films. The compositions of the kappa carrageenan in the Chit-KC films were 0%, 16.67%, 33.33%, 50.0%, and 100.0%. The films were characterized using FTIR, SEM, DTA-TGA, and XRD instruments to analyze their functional groups, morphology, thermal properties, and crystallinity. They were also tested for their solubility, swelling, water vapor permeability (WVP), and mechanical characteristics. The results revealed that the addition of kappa-carrageenan induced the formation of a polyelectrolyte complex. The polyelectrolyte complex caused an increase in swelling, crystallinity, and WVP values and a decrease in solubility, tensile strength, elongation, and elasticity. It also caused the formation of film layers and granules on the surface of the hydrogel film. The IR spectra exhibited that the Chit-KC hydrogel films contained O-H, C-H, C=O, S=O, C-O, and C-O-C groups. The DTA-TGA test results revealed that the film began decomposing at around 200°C and re-decomposing at 300°C.

EXTH-71. A MECHANISTIC INVESTIGATION INTO AUGER THERAPY: 2-DIMENSIONAL THIN-FILMS TO CHARACTERIZE THERAPEUTIC RANGEIN VITRO

Abstract Metallic nanoparticles can improve the accuracy and effectiveness of conventional radiotherapy in the treatment of solid tumors through a light-matter interaction known as the Auger effect. In this work, we present the assembly of an iron oxide (Fe3O4) nanoparticle (NPs) layer within a biocompatible polyelectrolyte film using ionic self-assembly to enable the spatial separation of NPs from their target cells. Films exhibited uniform nanoparticle coverage as well as strong stability in cell culture conditions. To investigate the applicability of NMDR with non-internalized NPs, conditions with (NP-PEM) and without (PEM) embedded nanoparticles were used to evaluate the therapeutic effect of physically separated nanoparticles on cells cultured on the film surface via a measure of intracellular reactive oxygen (ROS) generation and histone phosphorylation (yH2AX) after irradiation from a 137Cesium source. Cells cultured on NP-PEM demonstrated a 78.4% increase in ROS generation when compared to cells cultured on PEM films. When adjusting for cell count, NP-PEM films induce 70.5% greater ROS generation. In investigating nanoparticle-mediated deposition of radiation (NMDR), these films allow for the determination of the extent of the therapeutic effect when NPs are not internalized into their targeted cells, potentially providing indications with respect to off-target effects. Cells were irradiated on films with nanoparticle distances from 25.9 nm to 97.5 nm to interrogate the NMDR effect size at a range of distances. yH2AX phosphorylation exhibited an exponential decay until 69.8 nm, where there was no difference when compared to nanoparticle-free films. This work highlights the ability of iron oxide NPs to deliver NMDR at a known, quantifiable distance, providing insights for further translational applications.

Prediction of Hydrogen Diffusion Behavior under the Influence of Defect Structures in Stainless Steel Passivation Film Based on Molecular Dynamics.

The excellent corrosion resistance of stainless steel primarily relies on the formation of a dense passivation film on its surface. Stress corrosion and hydrogen embrittlement are the primary forms of damage to the stainless steel passivation film, leading to film rupture and subsequent corrosion of the stainless steel substrate. The passivation film exhibits semiconducting properties and typically consists of a bilayer structure with a chromium-rich inner layer and an iron-rich outer layer. This study employs molecular dynamics simulations to investigate the interaction energy between hydrogen atoms and pristine stainless steel passivation films (Fe2O3/Cr2O3) as well as those containing three different types of defects and predicts the diffusion processes of hydrogen atoms in passivation films. The results indicate that the strongest interaction energy of -1.4402 eV is observed between hydrogen atoms and the pristine passivation film. However, as defects emerge within the passivation film, the interaction energy decreases, with a minimum energy of -0.1931 eV observed for the film containing chromium vacancies (VCr), representing a nearly one-order-of-magnitude reduction compared to the defect-free case. Furthermore, the diffusion coefficients of hydrogen atoms in the three defective passivation films are calculated as 6.437 × 10-10, 8.249 × 10-10, and 50.892 × 10-10 m2/s, respectively. Notably, the presence of a VCr defect enhances the hydrogen diffusion coefficient by an order of magnitude compared to the pristine film. Anisotropic diffusion paths and properties are elucidated through an analysis of the self-diffusion behavior of hydrogen in different detective passivation films, providing a theoretical basis for the prediction of hydrogen-induced cracking and the development of early warning technologies for passivation film surface failure.

Depth Profiles of Crystallinity and Preferential Orientation and Surface Characteristics of Sputter‐Deposited CeO2 Thin Film Buffer Layers on Sapphire Substrates Evaluated Through Two‐Dimensional Grazing‐Incidence X‐Ray Diffraction

ABSTRACTTwo‐dimensional grazing‐incidence wide‐angle X‐ray diffraction data were acquired from CeO2 thin films serving as buffer layers on r‐cut sapphire substrates to investigate the depth profiles of crystallinity and preferential orientation as well as surface conditions. The thin film samples were sputter‐deposited under different conditions. Data were obtained at an X‐ray wavelength of 0.100 nm at 0.02° intervals from 0.06° to 0.30° at the grazing‐incidence angle. A 60‐nm‐thick CeO2 thin film sputter‐deposited under Ar (Ar‐60) and a 100‐nm‐thick CeO2 thin film sputter deposited using 10 vol.% O2 in Ar (O+Ar‐100) were found to have partially oriented three‐dimensional bulk crystal structures with preferential orientation in the (100) direction near the surface. The lattice constant for the Ar‐60 film was found to be approximately 0.30% smaller than that for a CeO2 standard, whereas the lattice constant for the O+Ar‐100 film was approximately 0.50% larger. Lattice mismatch between the CeO and CeO2 on the substrate surface is evidently not an issue based on the lattice constants near the surface. Hence, both films could be considered to represent optimal buffer layers for YBa2Cu3O6+δ thin film growth. However, even in the case of a CeO2 thin film suitable for use as a buffer layer, the difference in lattice constants between the interior and surface of an Ar‐60 film was found to be relatively small, whereas that for an O+Ar‐100 film was relatively large. These results show that it is important to analyze the film surface in detail by reducing the incidence angle to less than 0.1°.

Efficiency Improvement on Indium Tin Oxide Films for Dye-Sensitized Solar Cell Using Oxygen Plasma by Bias-Magnetron RF Sputtering Process

Dye-sensitized solar cells (DSSCs) are among the most widely studied thin-film solar cells because of their cost-effectiveness, low toxicity, and simple fabrication method. However, there is still much scope for replacing current DSSC materials due to their high cost, low volume, and lack of long-term stability. Accordingly, indium tin oxide (ITO)-nanorod films were fabricated by electron (E)-beam evaporation using the glancing angle deposition method in this study. Then, the ITO-nanorod was treated with oxygen plasma via a bias-magnetron radio-frequency (RF) sputtering process to improve the efficiency of DSSCs under a varying gas flow rate of 20, 40, 60, 80, and 100 sccm. The field emission scanning electron microscopy (FE-SEM) investigation of the ITO film structure revealed that the obtained nanorod structures have slightly different diameters. At the same time, an increase in the oxygen flow rate resulted in a rougher film surface structure. In this, the lower sheet resistance was received because of rougher morphology. When comparing the DSSCs efficiency (η) test results, we found that at a gas flow rate of 100 sccm, the highest efficiency value showed 9.5%. On the other hand, the ITO-nanorod without plasma treatment exhibited the lowest η. Hence, plasma technology can be practically applied to improve the η of DSSC devices. This study will be a prototype of a highly advanced solar cell manufacturing method for the solar cell industry.

Rapid quantitative analysis of semi-volatile organic compounds in indoor surface film using direct analysis in real time mass spectrometry: a case study on phthalates

Abstract. Direct analysis in real time mass spectrometry (DART-MS) has recently emerged as a promising approach for measuring semi-volatile organic compounds (SVOCs) on indoor surface films. However, its broader application in indoor environments is limited by low measurement repeatability and no separation of isomers. Herein we developed a sampling suite of indoor surface films for DART-MS analysis, optimized settings of DART to obtain higher analytical performance, and demonstrated the possibility of separating isomeric compounds using tandem mass spectrometry (MS/MS). Two pairs of isomeric phthalate esters, including di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) and diisobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP), were used as examples for method optimization and validation. Under optimized conditions, the instrument responses for all four compounds exhibited good linearity (r>0.992) and acceptable repeatability (intraday relative standard deviation (RSD) < 11.0 %). The limits of quantification for the four phthalate esters ranged from 0.042 to 0.24 ng cm−2. The uncertainty in the separation of isomeric components using MS/MS was < 11.4 %, which is acceptable for real sample analysis. To further assess the developed method, we analyzed 10 film samples collected side by side in an occupied office. DnOP was not detected. The RSD among samples was 6.1 % for DEHP, 4.6 % for DnBP, and 10.4 % for DiBP, indicating the overall good repeatability of the collection and measurement method developed. With improved performance, the developed method increases the feasibility of the DART-MS technique for monitoring the dynamics of chemical composition of indoor surface films.

Nanostructure of TiO\(_{2}\) and WO\(_{3}\) multilayer films deposited on ITO glass for electrochromic enhanced photocatalytic activity

The photocatalytic activity (PA) by electrochromic (EC) enhancement of single and multilayer films of TiO2, WO3, TiO2/WO3, and WO3/TiO2 was investigated. All films were deposited from metal on an ITO glass substrate using direct current (DC) magnetron sputtering via an oblique angle deposition (OAD) technique at 85°. Subsequently, a thermal oxidation (TO) process at 500℃ was applied for the samples to form metal oxide films. The morphology, elemental composition, crystal structure, and optical properties were studied by using field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and UV-vis spectroscopy, respectively. The photocatalytic properties were investigated by showing the degradation rate of methylene blue (MB) solution as an organic pollutant that was examined under ultraviolet irradiation of 300 µW∙cm‒2. The film samples were investigated by comparing the pre-color and colored states that were achieved through the EC process. The EC properties of WO3 led to increased charge insertion on the film surface. This observation was further supported by cyclic voltammetry (CV) testing, which revealed a higher current density for the thin film samples. The photodegradation results showed that the samples in the colored state exhibited a significantly higher degradation rate of MB compared to the pre-color state.

Pyridalthiadiazole-Based Molecular Chromophores for Defect Passivation Enables High-Performance Perovskite Solar Cells.

Passivation of defects at the surface and grain boundaries of perovskite films has become one of the most important strategies to suppress nonradiative recombination and improve optoelectronic performance of perovskite solar cells (PSCs). In this work, two conjugated molecules, abbreviated as CPT and SiPT, are designed and synthesized as the passivator to enhance both efficiency and stability of PSCs. The CPT and SiPT contain pyridalthiadiazole (PT) units, which can coordinate with undercoordinated Pb2+ at the surface and grain boundaries to passivate the defects in perovskite films. In addition, with the incorporation of CPT, the crystallized perovskite films exhibit more uniform grain size and smoother surface morphology relative to the control ones. The efficient passivation by CPT also results in better charge extraction and less carrier recombination in PSCs. Consequently, the CPT-passivated PSCs yield the highest power conversion efficiency (PCE) of 23.14 % together with better storage stability under ambient conditions, which is enhanced relative to the control devices with a PCE of 22.14 %. Meanwhile, the SiPT-passivated PSCs also show a slightly enhanced performance with a PCE of 22.43 %. Our findings provide a new idea for the future design of functional passivating molecules towards high-performance PSCs.