Preparation Of Films Research Articles

Crystallization Control Assists Annealing‐Free Fabrication of Printable Mesoscopic Perovskite Solar Cells with Power Conversion Efficiency over 17%

The one‐step drop‐casting for preparing perovskite films in three‐layer mesoporous for printable mesoscopic perovskite solar cells always results in insufficient filling of mesopores. A binary solvent based on 2‐methoxyethanol (2‐ME) and 1‐methyl‐2‐pyrrolidone (NMP) offers a method suitable for annealing‐free to prepare dense perovskite films in mesopores. The crystallization process of perovskite films in mesopores can be adjusted by the content of NMP in the solvent. The introduction of NMP enhances the density of the perovskite film based on the binary solvent system, optimizing the contact between the perovskite film and the mesoporous scaffold. When the ratio of 2‐ME to NMP is 9:1, the optimal device achieves impressive performance metrics, including a power conversion efficiency (PCE) of 17.28%, an open‐circuit voltage of 0.98 V, a short‐circuit current of 23.80 mA cm−2, and a fill factor of 74.08%. This represents the highest PCE achieved to date in the annealing‐free preparation of perovskite films for printable mesoscopic perovskite solar cells. Furthermore, devices based on this binary solvent system exhibit remarkable stability, with almost no loss in efficiency even after 120 days of storage in an air environment without encapsulation.

Blue Lead‐Free Perovskite Derivatives: Structural Diversity, Luminescence Properties and Light‐Emitting Diode Applications

AbstractHalide perovskite light‐emitting diodes (LEDs) have made remarkable advancements in both efficiency and stability. However, when compared to green and red LEDs, blue perovskite LEDs still lag behind in terms of efficiency and stability. Presently, efficient blue LEDs primarily rely on lead‐based perovskites, which goes against the environmentally friendly practices and restricts potential industrial applications. Consequently, there has been a surge of interest in academic research toward developing blue LEDs using lead‐free perovskites. This paper provides a comprehensive review of the structural diversity of lead‐free perovskite derivatives used for blue emission, encompassing Sn‐, Zr‐, Bi‐, Sb‐, Cu‐, Zn‐based halides as well as double perovskites. Various material synthesis techniques are discussed, such as nanocrystal preparation and film preparation. Additionally, the photoluminescence properties for different energy band structures are outlined, along with the luminescence mechanism involving energy transfer and strategies for enhancing luminous efficiency. The advancement in efficiency and stability of lead‐free perovskite LEDs is also examined in this review. Finally, the current challenges and future opportunities in advancing research on blue lead‐free perovskite derivatives and their potential application in LED technology is emphasized.

High-compatibility properties of Aronia melanocarpa extracts cross-linked chitosan/polyvinyl alcohol composite film for intelligent food packaging

Although the active and intelligent properties of rich in anthocyanin extracts added to films have been extensively studied, there remains a sparsity of research pertaining to the miscibility of blended films. This work focused on the miscibility of the chitosan/polyvinyl alcohol (CP) film caused by the addition of Aronia melanocarpa extracts (AME), which are rich anthocyanins and phenolic acids, and its effect on physicochemical and functional properties. AME facilitated the amidation reaction and ionic interaction of chitosan in CP films, leading to loss of the crystallinity degree of chitosan. Furthermore, the crystal disruption promoted the formation of hydrogen bonds with polyvinyl alcohol (PVA) with the promoted miscibility. CP film incorporated with 8 % AME possessed the highest tensile strength (26.79 MPa), and elongation at break (66.38 %) as well as excellent ultraviolet–visible (UV–vis) light barrier property, water vapor barrier properties, due to its high miscibility degree. Moreover, this film also showed excellent antioxidant, antibacterial activity, and pH response function, which could be used to monitor the storage of highly perishable shrimp. Hence, the AME provided extra functionality and improved miscibility between chitosan and PVA, which showed great potential for the preparation of high-performance bioactive-fortified and intelligent food packaging films.

Preparation of films based on reticulated fish gelatin containing garlic essential oil

Agro-industrial co-products, such as fish gelatin, stand out for their capacity in forming biopolymeric films, being biocompatible and non-toxic; however, its hydrophilicity poses a challenge. Essential oils, rich in bioactives, attract research interest aiming to enhance the protective barrier of films and enable their application in packaging. This study produced films based on cross-linked Nile tilapia skin gelatin, incorporating garlic essential oil. Gelatin obtained through partial collagen hydrolysis from the fish skin and cross-linked with gallic acid had hydroxyproline content of 10.02 g 100 g−1 and gel strength of 287 g, which were consistent with other studies. Oil extraction used supercritical CO2 as a solvent and ethanol as a cosolvent, following a factorial experimental design, evaluating the extraction temperature (40 °C and 70 °C) and cosolvent ratio (1:1 and 1:3), with three central points. Extraction was successful, with higher yields on a dry basis at 70 °C (88.35 %), using a 1:1 cosolvent ratio. Films incorporated with oil exhibited lower water vapor permeability (WVP) than those with only cross-linked gelatin (1.59 (g m−1 s−1 Pa−1) 1011). The film with the most suitable tensile strength (19.07 MPa), elongation (120.91 %), and WVP (1.09 (g m−1 s−1 Pa−1) 1011) properties contained garlic oil extracted at the central point (55 °C and 1:2). Thermal analysis indicated increased melting temperatures in films with added oil, suggesting low thermal degradation. These results suggest that garlic oil addition can improve the properties of fish gelatin-based films, making them promising for biodegradable packaging.

Effect of CdS on the Electrical Conductivity of Polyvinyl Alcohol (PVA) and Potassium Iodide (KI) thin films

In the past two decades, solid polymer electrolytes (SPEs) have attracted attention as a platform for electrochemical devices. Here polymer-based electrolytes have the advantage that they can be grown in a thin film, plus they are leak-proof. In the present work, we have used PVA:KI as the host polymer–salt complex with a composition of 85:15. Further, this PVA:KI complex dispersed with different wt% of CdS. Standard solution cast techniques have been used for thin film preparation. All prepared samples are characterized to study conductivity and structural changes. A maximum ionic conductivity of 2.47 X 10-7 S/cm was observed for 9wt% of CdS. Also, the band gap of these films was calculated and found to be between 2.4 to 2.9 eV. Also, the concentration and mobility of charge carriers were calculated to explain the change in conductivity pattern. This calculation was performed with the Schutt & Gerdes model. It is observed that the conductivity pattern mainly follows the concentration of charge carriers. DOI: https://doi.org/10.52783/pst.370

Electrodeposition fabrication of WO3/EuMOF film for fluorescence switch

In recent years, lanthanide metal organic frameworks have been widely used in various fields because of their excellent fluorescence properties. Fluorescence switch has also been considered as a research hot spot and widely applied in many fields. The combination of fluorescent material and electrochromic material has emerged in the preparation of fluorescence switch. Herein, a simple and rapid electrodeposition method is proposed for the preparation of amorphous EuMOF film. The whole process takes only half an hour under room temperature. The prepared amorphous EuMOF film exhibits significant emission peaks characteristic of Eu3+ when excited by 277 nm UV lamp. In addition, the prepared EuMOF is also applied in an electrochromic device to construct WO3/EuMOF fluorescence switch by stepwise electrodeposition using polystyrene microsphere as template. By changing the voltage, the coloring and fading of the device color, and the quenching and recovery of fluorescence can be reversibly regulated, in order to achieve the control of the “on” and “off” states of the fluorescence switch.

Investigations towards nanoscale precise polishing of Nb3Sn thin films for SRF applications

The superconducting radio frequency performance of Nb3Sn is significantly impacted by its near-surface composition and nanostructure. In this study, an innovative polishing technique for Nb3Sn thin films with nanoscale precision is proposed. Systematic angle-resolved X-ray photoelectron spectroscopy (ARXPS) analysis reveal that the mechanism of this polishing process involves the formation of a few nanometer-thick oxide layer on the film's surface, followed by the uniform removal of the oxide layers with HF rinse. It is approximated that the polishing depth achieved in a single cycle can reach several nanometers. Advanced material characterization demonstrates that optimized polishing process effectively eliminates compulsive tin droplets and potential tin-rich phases with poor superconductivity generated on the surface during the preparation of Nb3Sn thin films. Simultaneously, no additional impurity phase will be formed on the surface, and the surface roughness will remain undamaged. Meanwhile, the results of magnetic and electrical analysis show that the superconducting properties of the polished films are not affected. This polishing technique is anticipated to ease the stringent coating conditions for the preparation of high-performance Nb3Sn thin film superconducting cavity, and will be a valuable addition to the post-treatment process of Nb3Sn thin films.

Green‐Emissive Carbon Dots with a High Quantum Yield Applied for Photoconversion Film to Prevent from Blue Light Damage

AbstractHigh‐energy blue light is highly detrimental to health as it can penetrate the lens into the retina, potentially causing atrophy or even death of retinal pigment epithelial cells. To prevent the harmful effects of high‐energy blue light on our health, here the preparation of a photoconversion film specifically designed to block high‐energy blue light is reported, which is composed of green‐emissive carbon dots (G‐CDs) with a high photoluminescence quantum yield (PLQY = 95%) dispersed in polyvinyl alcohol (PVA) matrix. Notably, such a film (named as G‐CDs@PVA) not only converts an incident laser light with a short wavelength into a fluorescence with a longer wavelength, but also exhibits concentration‐dependent (0, 10, 20, and 30 wt.%) blue light barrier rate and green‐emissive intensity. With the increase of the concentration of G‐CDs in the film, the blue light barrier rate of the film as well as the maximum intensity of the green emission are also increased. When the concentration of G‐CDs reaches 30 wt.%, the blue light barrier rate of G‐CDs@PVA achieves up to 97%. Furthermore, G‐CDs@PVA film is attached to a blue light‐emitting diode (LED) chip to explore its practical application in the field of blocking blue light damage.

Stranski-Krastanov Growth of Two-Dimensional Covalent Organic Framework Films.

Insights into the formation mechanisms of two-dimensional covalent organic frameworks (2D COFs) at both the in-plane and interlayer levels are essential for improving material quality and synthetic methodology. Here, we report the controllable preparation of 2D COF films via on-surface synthesis and investigate the growth mechanism using atomic force microscopy. Monolayer, bilayer, and layer-plus-island multilayer COF films were successfully constructed on hexagonal boron nitride in a controlled manner. The porphyrin-based COF films grow in the Stranski-Krastanov mode, i.e., a uniform bilayer COF film can be formed through layer-by-layer growth in the initial stage followed by island growth starting from the third layer. Furthermore, fluorescence quenching caused by π-π stacking interactions between 2D COF neighboring layers was revealed. These results provide new perspectives on the synthesis of high-quality 2D COF films with controllable thickness and morphology, paving the way for a diverse range of applications.

Multifunctional composite flexible films of hydroxypropyl cellulose and silver nanowires

Flexible wearable devices have aroused attentions since the booming flexible electronic technologies, as well as the requirements for improved comfortableness and real-time monitoring for complex motion state of human body. Developing a flexible integrated wearable device with multi functions provides a promising route for next-generation wearable devices. Meanwhile, transparency and biocompatibility are also considered a lot. Herein, hydroxypropyl cellulose/silver nanowires (HPC/AgNWs) flexible composite films were fabricated with a facile two-step method. The fabricated composite films exhibited sufficient transparency and mechanical strength. More importantly, the HPC/AgNWs composite films afforded good motion sensing performances with current sensitivity as high as 350 %. It can accurately identify different bending angles and frequencies, and remained stable for more than 1000 bending cycles. Apart from being employed as motion sensors, the fabricated HPC/AgNWs could be also used for electrical heating and electromagnetic shielding. The films could be heated to more than 60°C at 3.0 V in 57 seconds, and the electromagnetic shielding efficiency reached more than 99.9 %. This study contributed a feasible strategy for the preparation of multifunctional flexible films which are expected to be further applicated in the field of wearable devices.

Anion Binding Interaction Enhances the Robustness of Iodide for High-Performance Perovskite Solar Cells.

Owing to the ionic bond nature of the Pb-I bond, the iodide at the interface of perovskite polycrystalline films was easily lost during the preparation process, resulting in the formation of a large number of iodine vacancy defects. The presence of iodine vacancy defects can cause nonradiative recombination, provide a pathway for iodide migration, and be harmful to the power conversion efficiency (PCE) and stability of organic-inorganic hybrid perovskite solar cells (HPSCs). Here, in order to increase the robustness of iodides at the interface, a strategy to introduce anion binding effects was developed to stabilize the perovskite films. It was demonstrated that the N,N'-diphenylurea (DPU), characterized by high anionic binding constants and a Y-shaped structure, provides a relatively strong hydrogen bond donor site to effectively reduce the iodine loss during film preparation and inhibits iodide migration in the device working condition. As expected, the reduced iodine loss considerably improves the quality of the perovskite films and suppresses nonradiative recombination. The performance of the device after DPU modification was significantly increased, with the PCE rising from 23.65 to 25.01% with huge stability enhancement as well.

Guanidine carbonate modified TiO2/Perovskite interface for efficient and stable planar perovskite solar cells

The rational design and modification of the buried interface are essential and challenging for high-performance perovskite solar cells (PSCs). TiO2 is a simple and readily available electron transport layer material, but its surface defects and poor interfacial contact with perovskite layers hinder its widespread application. Here, we propose an effective TiO2/perovskite interface modification strategy by introducing simple guanidine carbonate (GuaCO3) onto the surface of TiO2. Guanidine carbonate can improve the interfacial contact between TiO2 and perovskite, reduce non-radiative recombination, and enhance carrier extraction. Moreover, the PbI2 film grown on the TiO2/GuaCO3 substrate tended to become porous during the preparation of perovskite films by the traditional two-step method, which facilitated the complete reaction of organic ammonium salts with PbI2 and promoted the growth of high-quality perovskite films. The experimental results indicate that GuaCO3 can passivate the interfacial defects of TiO2/perovskite, as well as reduce the accumulation of interfacial charges. The device modified with GuaCO3 achieved a power conversion efficiency (PCE) of 23.39 %, which is significantly higher than that of the control device (21.73 %). After storage in an ambient environment at room temperature for 600 h, the unencapsulated device modified with GuaCO3 retained 78 % of its initial efficiency, while the control device retained only 57 % of its initial efficiency. These results indicate that interfacial modification with GuaCO3 is an effective strategy for improving the performance of PSCs.

Facile Preparation of Stable NiII‐ and CoII‐tetraaminophthalocyanine Electropolymers for Highly Efficient Heterogeneous Carbon Dioxide Reduction

This study focused on preparation of stable polymer films of NiII‐ and CoII‐tetraaminophthalocyanines, p‐NiTAPc and p‐CoTAPc, respectively, for highly efficient heterogeneous electrochemical carbon dioxide (CO2) reduction in a flow electrolysis cell. Major development represented in this work was fabrication of p‐NiTAPc and p‐CoTAPc films via electropolymerization of their corresponding monomers on carbon‐based substrates without using binder or conducting additive materials to obtain efficient gas diffusion electrodes (GDEs) for scalable, productive and selective CO2‐to‐CO conversion. The target polymers were characterized by UV‐visible spectrophotometry, attenuated total reflection‐Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray spectroscopy and cyclic voltammetry. According to controlled potential electrolysis and gas chromatography, p‐NiTAPc‐catalyzed CO2 reduction at –0.99V vs. reversible hydrogen electrode (RHE) gave 953 mL of CO in a period of 16 hours with current density and Faradaic efficiency (FE) of 109±1 mA·cm‐2 and 99±2%, respectively. A p‐CoTAPc‐modified GDE exhibited superior catalytic performance to the case of p‐NiTAPc in terms of catalyst stability and CO productivity by performing the continuous CO2 reduction at the potential of –1.10 V vs. RHE for up to 41 hours and affording almost 3 times higher amount of CO with the current density of 161±5 mA/cm2 and 95±2% FE.

Preparation, characterization, and application of pH-responsive biodegradable intelligent indicator film based on rose anthocyanins

An intelligent pH-responsive indicator film (CA/CMC/RA) was fabricated by blending carrageenan (CA), carboxymethylcellulose (CMC), and rose anthocyanin (RA). Fourier transform infrared spectroscopy revealed the formation of hydrogen bonds between CA/CMC and RA. X-ray diffraction analysis demonstrated that the addition of RA enhanced the crystallinity of CA/CMC films. The incorporation of RA altered the microstructure of CA/CMC composite films, resulting in a roughened surface. RA improved the a*, b*, thickness, opacity, and water vapor permeability of CA/CMC/RA films. Moreover, the addition of RA increased the elongation at break, while decreasing the tensile strength. RA significantly increased the antioxidant capacity of CA/CMC films. Furthermore, CA/CMC/RA films exhibited pH-responsiveness, showcasing distinct color changes in different buffer solutions. In the application test, the CA/CMC/RA indicator film was used as a label to monitor the freshness of the ribbon fish stored at 4 °C. The results indicated that the film's color changed from pink to yellow upon spoilage. The observations were consistent with the TVB-N value, which exceeded the set limit (30 mg/100g). Hence, the novel indicator film can serve as a food freshness indicator material.

Epitaxial growth of gehlenite in CaO–MgO–Al2O3–SiO2 based glass ceramic induced by Nb2O5 addition

In this study, the crystallization behavior of a CaO–MgO–Al2O3–SiO2 based glass ceramics with Nb2O5 addition was investigated by using DSC, XRD and TEM techniques. It was found that three crystalline phases, namely, CaNb2O6, diopside and Gehlenite (Ca2Al2SiO7), were formed from the glass matrix during the crystallization heat treatment. The CaNb2O6 phase was the first to precipitate from the glass matrix at around 850 °C, acting as a nucleating agent that facilitated the formation of Gehlenite (Ca2Al2SiO7) at 900–950 °C. The TEM observation revealed a consistent orientation relationship between the CaNb2O6 and the Gehlenite (Ca2Al2SiO7) phases, indicating that CaNb2O6 could induce the epitaxial growth of Gehlenite (Ca2Al2SiO7). This result provides a new insight into the preparation of Gehlenite epitaxial films and glass ceramics.

Preparation, characterization, and electrical properties of PVDF-ZnO nanocomposite thin films

Preparation, characterization, and electrical properties of PVDF-ZnO nanocomposite thin films

Effect of Ginger (Zingiber officinale) Extracts on Mechanical and Antimicrobial Properties of Ganyong Starch Edible Films as Primary Packaging of Crabstick

Research has been conducted on the effect of ginger (Zingiber officinale) extract addition in the combination of an edible film made from Ganyong starch, sorbitol and chitosan. This study aims to analyze whether this formulation can be used as a substitute packaging for crabsticks that have been using conventional plastic packaging. By using a variation of ginger extract concentrations of 0, 3%, 6% and 9% into 3 % Ganyong starch, 4 % sorbitol and 0.3 % chitosan (w/v). Mechanical characteristics were carried out in the form of tensile strength, elongation, young modulus, swelling, moisture content, thickness, and solubility test. Antimicrobial ability and DSC (Differential scanning calorimetry) for the thermal properties of the casted film were also conducted. Data was analyzed using One-way Anova SPSS version 29 with Turkey’s test. The addition of ginger extract to edible films based on Ganyong starch, sorbitol and chitosan can be used as primary packaging for crabsticks. The best formulation was found in the 6 % ginger extract variation with the results of swelling (95 %), moisture content (13 %), elongation (76 %), and antimicrobial properties of Escherichia coli (7.5 mm) and Bacillus cereus (6.9 mm). In addition, the melting temperature (Tm) of 6 % ginger extract concentration was also higher (134 °C), yet was not significantly different from the other variations. Therefore, this formulation has the potential as an alternative primary crabstick packaging. HIGHLIGHTS Preparation of edible film from 3 % Ganyong starch, 4 % sorbitol, 0.3 % chitosan with fixed concentration and 3 different variations of ginger extract concentration (0, 3, 6, and 9 %), respectively. Casting method of edible film as primary packaging of crabsticks Mechanical properties and antimicrobial activity against Bacillus cereus and Escherichia coli, gram-positive and gram-negative bacteria, respectively The 6 % ginger extract variation showed better results with elongation (76 %), moisture content (13 %), swelling (95 %), and antimicrobial properties of coli (7.5 mm) and B. cereus (6.9 mm) GRAPHICAL ABSTRACT

Advanced Technique for Fast Dissolving Film Preparation

Advanced Technique for Fast Dissolving Film Preparation

Recent advancement in the synthesis of zinc sulphide thin films

This research work has given an overview on the preparation of zinc sulphide thin films on different types of substrates (quartz, soda lime glass, silicon, polyethylene terephthalate film, fluorine-doped tin oxide glass, indium tin oxide coated glass, silica, stainless steel, mica, microscopy glass slide and (100) GaAs substrate) using different types of deposition methods. XRD data showed information about the different phases (cubic, wurtzite and hexagonal) presented in the obtained as-deposited films and annealed samples. Based on optical studies, the band gap was observed in the range of 2.6 eV to 3.87 eV with good absorption coefficient value (105 to 106 cm-1). Experimental results indicated these films could be used in solar cell applications, anti-reflection coating, photocatalysts, photo detector devices and laser-oriented coating applications.

Continuous Tunable Energy Band Tailoring Boosts Extending the Sensing of the Waveband Based on (InxGa1-x)2O3 Solar-Blind Photodetectors.

Rising wide bandgap semiconductor gallium oxide (Ga2O3) displays huge potential in performing solar-blind photodetection, with constraint in narrow detection wavebands in nature, whereas bandgap modulation through the introduction of exotic atoms into Ga2O3 has an essential effect on the tunable performance of photodetectors and the detection waveband. Here, a novel method for the preparation of (InxGa1-x)2O3 alloy films is proposed, and the continuous tuning of the bandgap in the range of 3.70-4.99 eV is achieved by varying the In-doping content. Alloy-based metal-semiconductor-metal photodetectors were fabricated, achieving a peak responsivity between 254 and 295 nm, superior performance compared to Ga2O3 photodetectors, with a photo-to-dark current ratio as high as 106, and a better optical image-sensing capability. This study offers new insight for high-performance detection of full solar-blind waveband ultraviolet light.