Polyethylene Naphthalate Film Research Articles

Measurement of the water vapor transmission rate at temperatures above 100 °C

ABSTRACT Water vapor transmission rate (WVTR) and water vapor permeability coefficient were measured at temperatures between 110 and 138°C using the modified cup method. The cup, placed in a Highly Accelerated Stress Test chamber, allowed water vapor to permeate the sample film attached to the cup. The WVTR was determined based on the increase in mass of the cup. To prevent sample damage during measurement, a cup with a pressure adjustment mechanism was utilized. Carrier-incorporated phosphorus pentoxide was used as the desiccant instead of anhydrous calcium chloride to ensure a consistent moisture absorption rate, especially at high temperatures. The water vapor permeability coefficients for the polycarbonate, polyimide, and adhesive films were distributed on an approximately straight line in the Arrhenius plot. Additionally, the Arrhenius plots for the polyethylene terephthalate and polyethylene naphthalate films captured the permeability bending point near the glass transition temperature. To accurately measure the high-temperatureWVTR, upper and lower limits were established for the weighing interval, cup mass gain, and WVTR measurement range.

Development of a phoswich detector utilizing bismuth germanate crystal scintillator and polyethylene naphthalate scintillation film

In this study, we present the development of a phoswich detector system employing a Bismuth Germanate (BGO) crystal scintillator in combination with a Polyethylene naphthalate (PEN) film plastic scintillator. Phoswich detectors can contribute to various applications, including radiation monitoring, medical imaging, and nuclear physics experiments, due to their ability to discriminate between different types of radiation. The thin PEN film is sensitive to α and β radiation, while the BGO scintillator exhibits good γ radiation detection efficiency. The incident radiation type and its energy can be determined by analyzing the difference in decay times between these two scintillators. This paper presents an analysis of the detector’s response to α, β, and γ radiation, and the particle tagging efficiencies are to be over 99.9%, 92%, and 99.8%, respectively.

Development of a Method to Measure Trace Levels of Uranium and Thorium in Scintillation Films

Abstract We have established a method to measure picograms-per-gram (pg g−1) levels of 238U and 232Th in scintillation films by combining the dry ashing method and inductively coupled plasma mass spectrometry. Trace amounts of 238U and 232Th were measured in up to 2 g of scintillation film with almost 100% collection efficiency. This paper details the experimental procedure, including the pretreatment of the samples and labware, detection limit of the method, collection efficiencies of 238U and 232Th, and measurement of 238U and 232Th in a polyethylene naphthalate film. This method is also applicable to 238U and 232Th measurements in other low-background organic materials for rare-event search experiments.

Nanosecond Partial Discharge Current Waveforms with Polyethylene Naphthalate Films on IEC(b) Electrode

The polyethylene naphthalate (PEN) film has been widely applied as a heat‐resistant thin insulation film and sensor film. For the safe and long application of the film in various products, one significant characteristic is the partial discharge (PD) resistivity. In this study, a well‐known IEC(b) electrode is used to measure PD characteristics such as the maximum partial discharge, qmax and fast PD current waveforms at AC peak voltages of 1–3 kVp and 50–1000 Hz over PEN films with thicknesses of 75, 50, or 25 μm. All experiments are conducted at room temperature of ~20 °C. The positive PD current is defined as the current flowing from a high‐voltage electrode to a ground electrode. The positive and negative qmax increased rapidly with the applied voltage increase but remained almost the same for the applied voltage frequency changes. The PD current duration time was less than 40 ns for the positive current and 30 ns for the negative current at all voltages, frequencies, and film thicknesses. It was deduced that the positive current peak magnitude was approximately twice of the negative one at all applied voltages, frequencies, and film thicknesses. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

Silver Printed Electrode on Poly-Imide (Pi) Film And Polyethylene Naphthalate (PEN) Film For ECG Monitoring Device: A Case Study

According to World Health Organization (WHO), cardiovascular disease (CVD) is among the tenth of primary global cause of death in 2017. However, this problem could be alleviated via early detections, especially for patients with a history of heart-related problems. In addition, ECG monitoring could reduce the cause of CVD if diagnose earlier thus reduce the risk of sudden death. The measurement of ECG signals is important to assist physicians about people heart and health conditions. The sophisticated characteristics of ECG signals could be acquired by using the good electrodes. Thus, electrodes play a vital role in ECG recording. The commercially available electrodes are the conventional wet electrode (gel) using silver/silver chloride (Ag/AgCl). The gel usage tends to dry gradually and could cause skin problems like dermal inflammation and skin irritation. Due to the limitations associated with conventional gelled electrode, dry electrode is expected to overcome the main limit of Ag/AgCl electrode. By fabricating the silver ink onto the polyimide (PI) and polyethylene naphthalate (PEN) substrates to produce a dry ECG sensor, which could withstand high temperature, reusable, and has been shown to be biocompatible. This study is a case study to measure the performance of dry electrode based by silver printed electrode on PI and PEN films in ECG application.

Measurement setup to simultaneously explore the location and energy of trapped charges in thin polymer films

This research proposes a unique system that combines charge density measurements by the laser intensity modulation method with optically excited current acquisitions using the photo-stimulated discharge technique (PSD). The purpose of this setup is to investigate the relationship between space charge properties (such as density, spatial depth, and time evolution) and the photocurrent-associated energies in order to gain new insights into the trap population and detrapping mechanisms in thin polymer films. This paper presents a description of the technical principles of both methods as well as the whole combined system. The results on a 12 μm-thick polyethylene naphthalate film show pyroelectric currents, which after processing indicate the formation of homocharges whose magnitude and depth decrease after light irradiation. The PSD currents allow the identification of two major energy bands at 3.4 and 5.9 eV (360 and 207 nm, respectively), possibly related to charge detrapping. In addition, current transients during constant wavelength irradiation show that incident photons can interact differently with trapped charges depending on the applied field.

Bilayer Indium Tin Oxide Electrodes for Deformation‐Free Ultrathin Flexible Perovskite Solar Cells

The superior electrical conductivity and optical transparency of indium tin oxide (ITO) make it an ideal electrode material for use in optoelectronic devices such as solar cells. When ITO electrodes are fabricated on very thin plastic substrates, however, the internal stress of the ITO layer causes the substrate to deform, severely limiting the device's performance. Herein, it is shown that ITO bilayers composed of an amorphous base layer and a crystalline overlayer lead to deformation‐free ITO electrodes. It is shown that an optimized bilayer structure is achieved when the internal stresses of the amorphous and crystalline layers approximately cancel. With this approach, mixed composition metal halide perovskite solar cells with ITO electrodes are successfully fabricated on 4 μm polyethylene naphthalate films. A power conversion efficiency (PCE) of 18.2% is obtained for the reference cell design, corresponding to a power‐to‐weight ratio of 24 W g−1 before encapsulation. The devices retain 95% of the original PCE after 1000 bend cycles, while under simulated indoor lighting (white LED, 200 lux, 5000 K) the PCE reaches 28.3%. A 3‐cell module with a designated area of 2.3 cm2 is realized with a power output of 28.1 mW and an open‐circuit voltage of 3.17 V.

Solid‐State and Flexible Black Electrochromic Devices Enabled by Ni‐Cu Salts Based Organohydrogel Electrolytes

AbstractSolid‐state black electrochromic devices (ECDs) are promising for smart window applications, particularly when privacy protection and low leakage are required. Herein, a Ni–Cu salts/poly(vinyl alcohol) based organohydrogel electrolyte is developed with superior visible‐light transparency (83.8%), ionic conductivity (0.11 mS cm−1), and mechanical properties (tensile strength: 11.1 kPa, breaking strain: 242.6%). Due to the high viscosity of the organohydrogel electrolyte, a homogeneous Ni–Cu alloy film with a surface roughness of around 11.2 nm can be electrodeposited under −3 V for 5 min, and the resulting black color can be retained for over 350 min with a transmittance increase of only 5% at the voltage‐off state. The solid‐state rigid ECD exhibits an outstanding optical contrast between the transparent and colored states (visible light transmittance: 70.8% vs 0.085%), excellent cycling stability with over 90% retention of optical contrast after 2000 cycles. Finally, a flexible ECD is fabricated with the organohydrogel electrolyte and annealed indium tin oxide (ITO)‐coated polyethylene naphthalate (PEN) films as flexible and durable electrodes. It exhibits good mechanical flexibility with transmittance modulation degradation of 10% after 800 bending cycles and switching stability for 400 cycles with up to 43% optical contrast.

Low-Temperature Plasma-Induced Changes in the Surface Chemical Composition of Polyethylene Naphthalate Films

Low-Temperature Plasma-Induced Changes in the Surface Chemical Composition of Polyethylene Naphthalate Films

Moisture barrier coating of AlN and Al2O3 multilayer film prepared by low-temperature atomic layer deposition

AlN and Al2O3 multilayer films intended as moisture barriers were deposited on polyethylene naphthalate films by remote-type plasma-enhanced atomic layer deposition. The deposition temperatures for AlN and Al2O3 were 160 and 20 °C, respectively. It was assumed that the AlN and Al2O3 interface would suppress the formation of dislocations and pinholes that lead to moisture diffusion. The AlN top layer was expected to act as a water-resistant layer. The surface morphology and the crystallinity of the deposited film were investigated by atomic force microscopy (AFM) and x-ray diffraction, respectively. The gas barrier property of the multilayer film was determined by the water vapor transmission rate, which was measured as 1.3 × 10−3 g/m2/day at a temperature of 40 °C and a relative humidity (RH) of 90%. The AFM image showed that the AlN top layer remained unchanged during water vapor contact for 120 h at 40 °C and 90% RH. The applicability of the multilayer film as a moisture barrier coating for compound semiconductor devices is discussed.

Effects of hydrogen and SiO2 buffer layer insertion on electrical properties of low-resistive indium tin oxide films formed on polyethylene naphthalate films

Low-resistivity transparent indium tin oxide (ITO) films were fabricated on flexible polymer substrates by RF-magnetron sputtering. Addition of hydrogen to the sputtering gas was effective in reducing the resistivity of ITO films deposited at room-temperature. Resistivity was further decreased by inserting a SiO2 buffer layer between the substrate and the ITO films. By optimizing the hydrogen pressure and SiO2 thickness, a resistivity of 3.4 × 10−4 Ω·cm was realized with a thickness of about 100 nm while maintaining an optical transparency of more than 85% in the visible range of the optical spectrum.

Contact and Adhesion Properties of Polyethylene Naphthalate Films Modified by DC Discharge

Contact and Adhesion Properties of Polyethylene Naphthalate Films Modified by DC Discharge

Investigation of polyesters as daytime radiative cooling materials

We discovered that polyesters, particularly polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), are potential candidates for daytime radiative cooling (RC). A significant temperature drop was observed in both PET and PEN films when they were exposed to liquid nitrogen. In addition, their RC efficiency was compatible with previously reported RC materials such as polydimethylsiloxane and soda-lime glass. Polyesters have advantages over other RC materials in terms of chemical stability, moldability, and impact resistance. In particular, PET can be utilized for daytime RC of solar cells due to its transparency in the visible region.

Контактные и адгезионные свойства пленок полиэтиленнафталата, модифицированных в разряде постоянного тока

The effect of the direct current discharge treatment on the contact properties of polyethylene naphthalate films has been studied. The change in the contact angles of wettability by water and glycerin, the work of adhesion, total surface energy, its polar and dispersion components on the time of plasma treatment at the anоde and cathode has been investigated. A significant increase in the hydrophilicity of the polymer surface and a good stability of the obtained characteristics during storage of modified films in air at room conditions are shown. The adhesion properties of the polymer were investigated using T-test method according to ASTM 1876. The data of peel resistance in contact with some adhesives for the initial and modified polymer were obtained. Atomic force microscopy was used to study changes in surface morphology under the influence of the direct current discharge treatment.

A novel and efficient technology of depositing Al2O3 film for OLEDs thin film encapsulation

Organic light-emitting diode devices (OLEDs) industry is developing rapidly, however, OLEDs are very sensitive to oxygen and water, determining how to achieve better barrier effect is one of the main challenges of flexible OLEDs technology. Based on the filtered cathode vacuum arc (FCVA) technology, a dense aluminum oxide (Al2O3) film with a thickness of about 100 nm was grown at room temperature for OLEDs encapsulation. The composition, structure, surface roughness, refractive index, light transmittance and other physical properties of the film were analyzed. The water vapor transmission rates (WVTRs) of the films were tested at 85 °C and 85% relative humidity (R.H.). Photoluminescence spectrum (PL) test was carried out to study the luminescence ability of tris(8-hydroxyquinoline) aluminum (Alq3) before and after the deposition of Al2O3 film. The results show that the amorphous Al2O3 film with dense structure prepared by FCVA has high visible light transmittance. The Al2O3 film reduces the WVTRs of the polyethylene naphthalate (PEN) film by four orders of magnitude and maintains the light-emitting performance of the organic light-emitting layer. These results indicate that the FCVA technology is a feasible method for preparing barrier films of flexible OLEDs.

SERS substrates based on self-organized dimple nanostructures on polyethylene naphthalate films produced via oxygen ion beam sputtering

Surface-enhanced Raman spectroscopy (SERS) utilizes metal nanostructures to enhance the intensity of Raman signals. Although many methods have been developed for fabricating SERS nanostructures, most involve multiple steps. Herein, we employed oxygen ion beam sputtering (IBS), a one-step technique suitable for processing flexible substrates in roll-to-roll processes for mass production, Specifically, one-step oxygen IBS was used to fabricate self-organized dimple nanostructures, whose area and roughness could be controlled using the ion irradiation energy density, on the surfaces of polyethylene naphthalate films. Gold nano-tips for SERS were subsequently obtained by evaporating gold onto the dimple nanostructures. Finite-difference time-domain (FDTD) simulations revealed that nano-tip structures with spacings of less than 10 nm increased the localized E-field enhancement, which improved the SERS signal. Fabrication at a low energy density (5.8 J/cm2) produced more nano-tips with spacings of less than 10 nm, corresponding to a density of 61.4 nano-tips/μm2. SERS analysis conducted with methylene blue at 638 nm and 785 nm demonstrated that the Raman signal intensity was stronger for SERS substrates fabricated with low energy density (5.8 J/cm2) than for substrates fabricated with high energy density (17.3 J/cm2), because of the high density of nano-tips on the former substrate.

Wavelength-shifting performance of polyethylene naphthalate films in a liquid argon environment

Liquid argon is commonly used as a detector medium for neutrino physics and dark matter experiments in part due to its copious scintillation light production in response to its excitation and ionization by charged particle interactions.As argon scintillation appears in the vacuum ultraviolet (VUV) regime and is difficult to detect, wavelength-shifting materials are typically used to convert VUV light to visible wavelengths more easily detectable by conventional means.In this work, we examine the wavelength-shifting and optical properties of poly(ethylene naphthalate) (PEN), a recently proposed alternative to tetraphenyl butadiene (TPB), the most widely-used wavelength-shifter in argon-based experiments.In a custom cryostat system with well-demonstrated geometric and response stability, we use 128 nm argon scintillation light to examine various PEN-including reflective samples' light-producing capabilities, and study the stability of PEN when immersed in liquid argon.The best-performing PEN-including test reflector was found to produce 34% as much visible light as a TPB-including reference sample, with widely varying levels of light production between different PEN-including test reflectors.Plausible origins for these variations, including differences in optical properties and molecular orientation, are then identified using additional measurements.Unlike TPB-coated samples, PEN-coated samples did not produce long-timescale light collection increases associated with solvation or suspension of wavelength-shifting material in bulk liquid argon.

Optimization and characterization of detector and trigger system for a KAPAE design

The Kyungpook National University Advanced Positronium Annihilation Experiment (KAPAE) aims to study ortho-positronium annihilation including invisible and visible exotic decay processes. The detector for this experiment consists of two main parts: the trigger part and the γ-ray detection part. In this study, we focused on the development of the trigger and γ-ray detection setup for the KAPAE detector. In the trigger setup, the suitable thickness of the plastic scintillator for positrons trigger is determined. The aerogel and nitrogen gas environment in which ortho-positronium can reduce the pick-off effect for 3-γ annihilation is created. The γ-ray detection part consists of 196 bismuth germanate (BGO) crystals covered with reflectors. The light yield and energy resolution uniformity of BGO crystals and the best suitable reflector for better light collection are evaluated. The source position dependency test for the BGO crystals are also examined. Single layer of polyethylene naphthalate (PEN) film plastic scintillator and aerogel with the continuous flow of nitrogen gas are found well suited for positrons trigger and annihilation environment, respectively. The light yield and its uniformity of 196 BGO crystals confirm its application for γ-ray detection in the KAPAE detector. Moreover, the VM2000 are found the best suitable reflector due to the small thickness and good reflectivity as compared to Teflon reflector.

유연한 유기태양전지의 수분 투습 방지를 위해 원자층 증착법으로 제조된 Al 2 O 3 박막에 대한 연구

A moisture barrier layer with high density and uniformity is essential for increasing the lifespan of optoelectronic devices such as flexible organic solar cells, LEDs, and photodetectors. In this study, various surface pre-treatments (O2 plasma, UVO treatment, Al seed layer, and thermal annealing process) were performed on a polyethylene naphthalate (PEN) film to form a functional group of chemical adsorption with the atomic layer deposition (ALD) precursor. We investigated the effect of the surface pre-treatment of a PEN substrate for a deposition of Al2O3 thin film in terms of the deposition uniformity and water vapor transmittance rate (WVTR). For example, the root mean square roughness of the bare PEN film/Al2O3 was RRMS=3.26 nm, whereas the O2 plasma treated PEN film/Al2O3 had RRMS=0.99 nm because of the presence of a functional group. As a result, WVTR of bare PEN film/Al2O3 was 0.83 g/m²/day, whereas that of O2 plasma treated PEN film/Al2O3 decreased to 0.38 g/m²/day.

Versatile bifunctional building block for in situ synthesis of sub-20 nm silver nanoparticle and selective copper deposition

In this work, a new bifunctional building block is presented for the development of versatile photosensitive resists, which enable in situ synthesis of sub-20 nm silver nanoparticles (AgNPs). In addition, practical adaptation to a palladium (Pd)-free electroless plating process verifies the facile fabrication of a metallic grid-based transparent conductive film. The building block is an aromatic small molecule with α,β-unsaturated acryloyl group and para-hydroxyl group protected by an acid-labile group (i.e., Di-tert-dicarbonate (referred to as Boc anhydride)). Spectroscopy analysis verifies the ease of photopolymerization as well as deprotection of Boc from the para-hydroxyl group where plays a key role in Ag+ reduction. The studies on plasmon absorption, morphology and elemental analysis confirm that the in situ synthesized AgNPs are sub-20 nm with a uniform distribution in the polymer matrix, which is important for efficient catalytic performance in electroless copper (Cu) deposition. In addition, the photosensitive resist exhibited excellent process reliability with respect to photolithographic patterning process and electroless plating under strong alkaline solutions (pH 10–12). Finally, the present work demonstrates the successful fabrication of sub-3 μm Cu metal grids on a polyethylene naphthalate (PEN) film.