Conductivity Of Films Research Articles

The role of coalescence and ballistic growth on in-situ electrical conduction of cluster-assembled nanostructured Sn films

The electrical conduction of nanostructured Sn films assembled via Supersonic Cluster Beam Deposition is studied in-situ during film growth. The kinetic energy of Sn nanoparticles, in combination with low melting point of Sn, promotes coalescence phenomena, enabling the investigation of their impact on film morphology and on percolation threshold. A percolation threshold occurring at thicknesses much larger than the dimensions of Sn nanoparticles suggests that coalescence leads to the growth of disconnected, island-like structures. The deposition rate is found to influence coalescence dynamics during the early stages of film growth, allowing for the tuning of film microstructure from a more compact, island-like morphology to a more porous structure. The percolation threshold shifts accordingly from 24 nm to 3 nm film thickness. Upon completion of the percolation phase, film resistivity settles at values 2–3 orders of magnitude larger than that of bulk Sn, attributed to the nanogranular nature of cluster-assembled films. During the “3D conduction” phase, resistivity exhibits an increasing trend with thickness following a power law with an exponent value of 0.76–0.78. This behavior is attributed to the decrease in the density of interconnections between particles in the topmost layer during film growth, consistent with expectations in ballistic growth processes.

Enhancing the Responsiveness of Thermoelectric Gas Sensors with Boron-Doped and Thermally Annealed SiGe Thin Films via Low-Pressure Chemical Vapor Deposition.

Thermoelectric gas sensor (THGS) devices with catalysts and Si0.8Ge0.2 thin films of different boron doping levels of 1018, 1019, and 1020 cm-3 were fabricated, and their transport properties are investigated. SiGe films were deposited on Si3N4/SiO2 multilayers on Si substrates using low-pressure chemical vapor deposition (LPCVD) and thermally annealed at 1050 °C. The Seebeck coefficients of the SiGe films were increased after thermal annealing, ranging from 191 to 275 μV/K at temperatures of 74 to 468 °C in air, and reaching the highest power factor of 6.78 × 10-4 W/mK2 at 468 °C. The thermal conductivity of the SiGe films varied from 2.4 to 3.0 W/mK at 25 °C. The THGS detection performance was tested for the H2 gas in air from 0.01 to 1.0%, and compared to the thermoelectric properties of the SiGe films. The high-temperature annealing treatment process was successful in enhancing the thermoelectric performance of both the SiGe films and sensor devices, achieving the best THGS performance with the sensor device fabricated from the annealed SiGe film with 1018 cm-3 boron-doped Si0.8Ge0.2.

Thermal conductivity of epoxy resin films doped with a polythiophene/graphene complex or aluminum nitride

AbstractPolymer composites with thermal conductivity are attractive for heat dissipation in electronic devices. We prepared epoxy resin‐based composite films filled with polythiophene [poly(3‐hexylthiophene‐2,5‐diyl)] (P3HT)/graphene complex or aluminum nitride (AlN). The composite films were characterized by electron microscopic observation, thermogravimetric analysis, and thermal conductivity measurements. The addition of a small content of P3HT/graphene complex (<1 wt%) increased both the out‐of‐plane and in‐plane thermal conductivities of the epoxy resin. The addition of AlN also increased thermal conductivity, but ≥40 wt% was required to obtain thermal conductivity comparable with that of an epoxy resin film doped with 0.9 wt% P3HT/graphene complex. The present results illustrate the potential of P3HT/graphene complexes as fillers for improving the thermal conductivity of epoxy resins without affecting their insulating properties.Highlights Polythiophene/graphene fillers increased epoxy resin films' thermal conductivity. To raise the thermal conductivity of epoxy resin films high AlN content was needed. In‐plane/out‐of‐plane epoxy resin films' thermal conductivities were evaluated.

Effect of Mo and W co-doping on optical, morphological, electrical and electrochemical properties of Co3O4 thin film

In this study, it was aimed to produce cobalt oxide (Co3O4) thin films with improved optical, electrical, and electrochemical properties for device applications with a simple and low-cost method. Mo, W, and dual Mo and W at the ratio 10 wt% of Co3O4 were added into the solutions. The prepared solutions were coated on glass substrates by spin coating method. The produced thin films' structural, morphological, optical, electrical, and electrochemical properties were examined. As a result of doping, the optical, morphological, conductivity, and electrochemical properties of Co3O4 thin films improved and more stable structures were formed. The Mo and W co-doping provided the most improvement in the properties of the Co3O4 thin film. The results obtained showed that the Mo and W co-doped Co3O4 thin film is a potential candidate for highly efficient electrochemical applications.

Bio-based epoxy resin/carbon nanotube coatings applied on cotton fabrics for smart wearable systems

Electroactive coatings for smart wearable textiles based on a furan bio-epoxy monomer (BOMF) crosslinked with isophorone diamine (IPD) and additivated with carbon nanotubes (CNTs) are reported herein. The effect of BOMF/IPD molar ratio on the curing reaction, as well as on the properties of the crosslinked resins was first assessed, and it was found that 1.5:1 BOMF/IPD molar ratio provided higher heat of reaction, glass transition temperature, and mechanical performance. The resin was then modified with CNT to prepare electrically conductive nanocomposite films, which exhibited conductivity values increased by eight orders of magnitude upon addition of 5 phr of CNTs. The epoxy/CNT nanocomposites were finally applied as coatings onto a cotton fabric to develop electrically conductive, hydrophobic and breathable textiles. Notably, the integration of CNTs imparted efficient and reversible electrothermal behavior to the cotton fabric, showcasing its potential application in smart and comfortable wearable electronic devices.

Enhanced Performance of Complementary Electrochromic Device with Hierarchical‐Porous NiO x Decorated ITO Glasses as the Transparent Conductive Electrodes

To pursuit advancing electrochromic technology, the preparation of a novel hierarchical‐porous NiOx‐decorated ITO transparent conductive electrode was developed through the vapor‐assisted conversion and subsequent calcination processes. The modified transparent electrode exhibited advantages in the electrodeposition of conductive polymer films, which significantly enhanced electrochromic cycling stability. Moreover, the complementary electrochromic device based on NiOx‐decorated ITO transparent electrode was fabricated, demonstrating rapid response time (1.75 s for coloration and 0.87 s for bleaching), high optical contrast (53.4%), and remarkable cycling stability (90% optical contrast retention over 2000 cycles). This finding holds prominent potential for applications in related fields.

Effect of barium doping on the behavior of conductivity and impedance of organic-inorganic perovskite films

This research focuses on the comparative analysis of effect of barium doping on the behavior of conductivity and impedance of organic-inorganic perovskite films, with an emphasis on their potential application in photovoltaic technology. The structural and electrical characteristics of CH3NH3PbI3 thin films with and without Ba are examined. Atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction are used to investigate the morphology and structure of the samples. It was found that light-dependent transport in CH3NH3PbI3 thin films in the temperature range of 77–295 K leads to a tenfold decrease in the activation energy; this decreases from 160 – 280 meV to 10–20 meV as the temperature drops from 300 to 77 K. Light induces an increase in the activation energy at low temperatures, rising from 10 meV in darkness to 15–20 meV in light. CH3NH3PbI3 thin films doped with Ba stand out due to their notably higher photoluminescence intensity, suggesting an enhanced crystalline quality and a reduced defect density. Such characteristics are crucial for optimizing the efficiency of solar cells.

Two-dimensional phthalocyanine-based molecular additives realize efficient hole transport and enhanced ion immobilization for durable perovskite solar cells

Perovskite solar cells (PSCs) have demonstrated high promises in low-cost manufacture and outstanding power conversion efficiencies (PCEs), however, long-term operational stability has become the major obstacle challenging the scalable application of this technology. Although the state-of-the-art hole transport layer (HTL) based on Spiro-OMeTAD becomes the indispensable component in high-efficiency PSCs, the dopants in the HTLs cause severe stability issues of ion migration and phase segregation, all of which induce the degradation of HTLs in the aspects of film conductivity and microstructures. Here we rationally design a two-dimensional phthalocyanine-based molecular additive (TB-C8-Ni) for the HTLs in order to enhance the carrier transportation and immobilize the ions. The incorporation of [8-(4-tert-butylphenoxy)octyl]oxy alkyl units as the side groups in TB-C8-Ni is essential to increase the solubility and improve the HTL uniformity. The superior planar structure of TB-C8-Ni favors the hole transportation and suppresses the migration of lithium ion under the environmental stress, which achieves reliable HTLs and devices. Consequently, the devices based on TB-C8-Ni exhibit boosted open-circuit voltage and fill factor, delivering an increased efficiency from 20.93% to 22.34%. More importantly, the additive TB-C8-Ni in the HTLs reinforces the moisture stability of devices, enabling to maintain 90% of initial efficiency after 2300 h in air.

High-Performance W-Doped Bi0.5Sb1.5Te3 Flexible Thermoelectric Films and Generators.

Bi-Sb-Te-based thermoelectric materials have the best room-temperature thermoelectric properties, but their inherent brittleness and rigidity limit their application in the wearable field. In this study, W-doped p-type Bi0.5Sb1.5Te3 (W-BST) thin films were prepared using magnetron sputtering on polyimide substrates to create thermoelectric generators (TEGs). Bending tests showed that the thin film has excellent flexibility and mechanical durability, meeting the flexible requirements of wearable devices. W doping can significantly increase the carrier concentration, Seebeck coefficient, and electrical conductivity of BST thin films. At 300 K, the power factor of the W-BST film is 2.25 times higher than that of the undoped film, reaching 13.75 μW cm-1 K-2. First-principles calculations showed that W doping introduces significant impurity peaks in the bandgap, in which W d electrons remarkably hybridize with the Sb and Te p electrons, leading to an improved electrical conductivity of BST films. Furthermore, W doping significantly reduces the work function of BST films, thereby improving the carrier mobility. A TEG module fabricated from four layers of W-BST thin films achieved a maximum output power density of 6.91 mW cm-2 at a temperature difference of 60 K. Application tests showed that the flexible TEG module could power a portable clock using the temperature difference between body temperature and room temperature. At a medium temperature of 439 K, the assembled TEG module can provide a stable output voltage of 1.51 V to power a LED. This study demonstrates the feasibility of combining inorganic thermoelectric materials with flexible substrates to create high-performance flexible TEGs.

Interface Defects Dependent on Perovskite Annealing Temperature for NiOX-Based Inverted CsPbI2Br Perovskite Solar Cells.

Nickel oxide (NiOX) is an ideal inorganic hole transport material for the fabrication of inverted perovskite solar cells owing to its excellent optical and semiconductor properties. Currently, the main research on developing the performance of NiOX-based perovskite solar cells focuses on improving the conductivity of NiOX thin films and preventing the redox reactions between metal cations (Ni3+ on the surface of NiOX) and organic cations (FA+ or MA+ in the perovskite precursors) at the NiOX/perovskite interface. In this study, a new type of interface defects in NiOX-based CsPbI2Br solar cells is reported. That is the Pb2+ from CsPbI2Br perovskites can diffuse into the lattice of NiOX surface as the annealing temperature of perovskites changes. The diffusion of Pb2+ increases the ratio of Ni3+/Ni2+ on the surface of NiOX, leading to an increase in the density of trap state at the interface between NiOX and perovskites, which eventually results in a serious decline in the photovoltaic performance of solar cells.

Robust ZTO-reinforced Ag nanowire hybrid transparent conductive thin films with absorption-enhanced electromagnetic interference shielding property

Technological advances have accelerated the pursuit of transparent conducting thin films (TCFs) with superior mechanical properties, durability, efficient optoelectrical performance and substrate compatibility as a pivotal focus in the realm of flexible transparent electronics. Against this background, this work investigates the fabrication of multilayer silver nanowire (AgNW) thin films reinforced by zinc tin oxide (ZTO) thin film encapsulation on polycarbonate substrates by a combination of sputtering and spin-coating techniques. An investigation of the influence of AgNW percolation networks on the optoelectrical properties of ZTO/AgNW/ZTO hybrid thin films was carried out. The impact of ZTO protective layers on the enhancement of electrical properties, adhesivity, flexibility and environmental stability of the multilayer TCF was elucidated. Additionally, to explore the compatibility of the fabricated TCF in integrated device and stealth applications, its electromagnetic interference shielding properties were investigated. The hybrid TCF showed 99.47% EMI shielding efficiency with an absorption-dominant EMI shielding effectiveness of 22.7 dB in the x-band region.

Ionic liquid reinforced NaSICON-type oxide electrolyte films enabling solid state conversion metal fluoride-lithium batteries

Solid-state batteries (SSBs) with metal fluoride cathodes are an exciting combination due to their high theoretical energy density and good safety. However, owing to the high chemical compatibility requirements between metal fluoride cathode and the solid-state electrolyte (SSE), developing an adaptable SSE film with comprehensive properties is particularly challenging. Herein, a class of ionic liquid (IL) reinforced oxide SSE films was proposed. Among them, the combination of Li1.5Al0.5Ge1.5(PO4)3 (LAGP) oxide SSE and EMIM-based IL (LAGP-EMIM) exhibits good flame-retardant properties, exceptional air stability, high ionic conductivity and excellent chemical stability. The introduction of ILs can increase the ion transport channels in SSEs and render the usage of dry-process, well addressing the contradiction between the flexibility and ionic conductivity of oxide films. The thickness of LAGP-EMIM films is 59 μm and they show the highest ionic conductivity of 1.05 mS cm−1 among the NaSICON-type oxide-based SSE films till now. In addition, it can be stably matched with the conversion metal fluoride cathodes such as FeF3 and CuF2 to construct semi-solid-state batteries, delivering high initial discharge capacity of 820.2 and 539.6 mAh g−1, respectively. The present work shed new insight into designing the composite electrolytes toward the next-generation solid state conversion batteries.

Heat Dissipation Capability of Stagger-Stacked Double Data Rate Module

In this study, we introduce a stagger-stacked DDR module that comprises one IPD chip (top die) along with four memory chips initially. The steady-state thermal characteristics of this configuration were empirically assessed using a dedicated thermal test vehicle. The purpose of this research is to investigate the module’s junction temperature by adjusting four factors: the thermal conductivity of the molding plastic, chip thickness, chip misalignment length, and the thermal conductivity of the adhesive film. We observed that the junction temperature decreases with an increase in the chip staggered length. An improved orthogonal experimental method was utilized to achieve the optimal design of the module. The optimal junction temperature has decreased by 4.74% compared to the initial value. Additionally, three alternative packaging technologies—cantilever, pyramid, and a combination of cantilever and pyramid—were evaluated for the benchmarking of the thermal performance. Ultimately, the stagger-stacked package demonstrated a reduction in the junction temperature by 3.62%, 7.95%, and 5.63%, respectively, when compared to the three traditional stacked packages.

Probing iodide/iodonium salt interactions with single-walled carbon nanotubes for resilient electrochemical capacitor

Self-standing films from single-walled carbon nanotubes (SWCNTs) were successfully used as electrochemical capacitors’ (ECs) electrode material, which exhibited state-of-the-art characteristics. The surface of SWCNTs was modified by iodonium salt molecules that substantially and permanently improved their electrical conductivity. The addition of pyridinium iodine chloride salt (IPyCl) quadrupled the value of the electrical conductivity of the SWCNT film, which reached values as high as 1022 S cm−1. Subsequently, the electrochemical performance of the newly designed self-standing SWCNTs with deposited IPyCl in aqueous neutral 1 M Li2SO4 and redox-active 1 M KI electrolytes was thoroughly analysed. Because redox activity of iodine species was observed mainly on the positive electrode, activated carbon with a developed surface area was used as a negative electrode to balance the faradaic charge. Due to the notable stability of iodonium salt dopant (instead of labile halogen-containing compounds typically used for SWCNT doping), robust charge/discharge performance of EC was demonstrated (> 10 000 cycles) in Li2SO4 electrolyte. Moreover, a significant improvement of capacitor metrics (from 49 to 75 F g−1) was obtained when electrodes modified by previously unexplored iodonium salt were utilized in 1 M KI electrolyte. Extensive analysis of the obtained data led to the elucidation of the doping mechanism responsible for the aforementioned achievements. The novel SWCNT-based electrodes enhanced with iodonium salt are auspicious materials, which can be used to build EC systems of appreciable capacitance.

Flash graphene and poly(o-methoxy aniline) for the composition of a solvent-based conductive ink

Conductive inks are essential components in electronics as they enable the printing of electronic circuits and components on diverse surfaces. Furthermore, they can be easily tailored to enhance chemical bonding with specific targets in sensing devices. This technology plays a crucial role in the development of both rigid and wearable sensors. Conductive inks for printed electronics and sensor devices should possess several key characteristics, including high conductivity, flexibility, affordability, and compatibility with various substrates. However, conventional conductive inks based on metal nanoparticles tend to be expensive and lack flexibility. This study aims to produce a conductive ink comprised of carbon-black-derived flash graphene (CBFG) and poly(o-methoxy aniline) (POMA), which can be applied to electronic devices. The structures and morphology of both precursors were assessed, and the electrical conductivity of ink coatings containing CBFG, POMA, and a combination of both was investigated. The effect of each component's concentration on the ink's electrical conductivity (EC) was investigated using a 23 factorial design of experiment. In conclusion, the most conductive film presented an EC of approximately 0.768 S m−1 when the concentrations of graphene, POMA, and binder were 40.0, 2.0, and 4.0 mg L−1, respectively. While further research is needed to explore the flexibility and adhesion properties of the ink on different substrates, our solvent and organic-based conductive ink offer environmental benefits and boost sensor performance.

Impact of crystallinity on thermal conductivity of RF magnetron sputtered MoS2 thin films

This study investigates the effects of sulfur atomic defects and crystallinity on the thermal conductivity of MoS2 thin films. Utilizing scanning transmission electron microscopy (STEM), X-ray diffraction (XRD), and Raman spectroscopy, we examined MoS2 films, several nanometers thick, deposited on Si/SiO2 substrates. These films were prepared via a combination of RF magnetron sputtering and sulfur vapor annealing (SVA) treatment. Structural analyses, including cross-sectional STEM and in-plane and out-of-plane XRD measurements, revealed an increase in the S/Mo ratio and grain size of the MoS2 films following SVA treatment. Notably, the in-plane thermal conductivity of MoS2 films treated with SVA was found to be at least an order of magnitude higher than that of films without SVA treatment. This research suggests that the in-plane thermal conductivity of MoS2 thin films can be significantly enhanced through crystallinity improvement via SVA treatment.

PH-sensitive fractal structured polyaniline in the honeycomb-patterned porous polymer film for the detection of dopamine and glucose

Using highly pH-sensitive fractal structured polyaniline (f-PANI) inducing conductivity change in the honeycomb-patterned (HCP) porous polymer film, we have applied for the detection of dopamine and glucose. Fractal-structured PANI in the HCP porous polymer film is formed by the same method recently reported using solid–liquid interfacial reaction. For the interfacial reaction, the HCP polystyrene (PS) porous film containing benzoyl peroxide (BPO) was immersed into the aniline aqueous solution under conditions of non-stirring for the growing of fractal structure instead of aggregated PANI. The pH sensitivity of the conductivity of the HCP film functionalized with fractal structured PANI was so high compared to the HCP film functionalized with simple aggregated PANI (a-PANI) under stirring conditions for the solid–liquid interfacial reaction. By using the high pH sensitive fractal structured PANI functionalized HCP film, dopamine, and glucose were selectively detected. The film acts as a micro reactor for the effective detection of dopamine and glucose.

Enhanced Opto-electronic Properties of Nd Doped CuO Thin Film

Here, pure, and Nd-doped CuO thin films with different composition (0.5 mol%, 1 mol%, 3 mol% and 5 mol%) were prepared following sol-gel spin coating route. X-ray diffraction analysis exhibited polycrystalline monoclinic structure of the films. Crystallite size and micro-strain were calculated from XRD analysis. As Nd doping was increased, crystallite size decreased for any addition beyond 0.5 mol%. Micro-Strain was also increased with increasing Nd doping indicating the lattice misfit because of size difference of Cu2+ and Nd3+. Optical properties of the pristine and Nd doped films were characterized using UV-visible spectrophotometry. The bandgap values were 1.92, 1.90, 1.87, 2.02 and 1.97eV for undoped, 0.5 mol%, 1mol%, 3 mol% and 5 mol% Nd doped films, respectively. Various optical parameters and dielectric constants were calculated for various optoelectronic applications. The topography of the films was studied using Atomic Force Microscopy and it revealed that the average roughness of the films varied in the range of 4.9 to 8.1nm. Electrical conductivity of the undoped film was increased from 0.315 to 0.596 Scm-1 for 5 mol% Nd doping which was measured using a 4-point probe method. Hall measurements showed an increment of carrier concentration by an order of 10 for the 5 mol % Nd doping compared to undoped CuO thin film, where charge carrier mobility was also increased from 0.102 to 0.453 cm2V-1s-1. However, for the maximum doping concentration of 5 mol%, the films remained p-type semiconductor confirmed by the positive value of the co-efficient RH.

Porous highly conductive PEDOT film for high-performance supercapacitors

Thick and highly conductive poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate films with ideal porous structure are fulfilling as electrodes for supercapacitors. However, the homogeneous micro-structure without the aid of templates or composite presents a significant obstacle, due to the intrinsic softness of the dominant PSS component. In this study, we have successfully developed a porous configuration by employing a solvothermal approach with ethylene glycol (EG) as the solvent. The synergistic action of elevated pressure and temperature was crucial in prompting EG to tailor the microstructure of the PEDOT:PSS films by removing non-conductive PSS chains and improving PEDOT crystallinity, and the formation of a porous network. The resulting porous PEDOT:PSS films exhibited a high conductivity of 1644 ​S ​cm−1 and achieved a volumetric capacitance record of 270 ​F ​cm−3, markedly exceeding previous records. The flexible all-solid-state supercapacitor assembled by the films had an outstanding volumetric capacitance of 97.8 ​F ​cm−3 and an energy density of 8.7 ​mWh cm−3, which is best one for pure PEDOT:PSS-based supercapacitors. Grazing-incidence wide-angle X-ray scattering, X-ray photo-electron spectroscopy, and other characterizations were carried out to characterize the structure evolution. This work offers an effective novel method for conducting polymer morphology control and promotes PEDOT:PSS applications in energy storage field.

High electrical conductivity and bending resistance of Ag NPs/Ag flakes composite silver paste are achieved by sintering Ag NPs

The investigation of conductive silver pastes and inks has witnessed extensive research within the domain of printed electronics in recent years, primarily owing to the exceptional electrical conductivity and steadfastness intrinsic to silver. This paper introduces an approach for the fabrication of stable, cost-effective, and low-resistance conductive silver paste tailored for flexible printed circuits. This method facilitates the solidification of the conductive silver paste into a highly conductive silver film at a curing temperature of 250 °C. In the process of preparing the conductive silver paste, Ag flakes is subject to modification through the incorporation of Ag NPs, which are subsequently sintered at a low temperature curing setting. The sintering of Ag NPs serves to establish connections between adjacent particles of Ag flakes within the paste, thereby enhancing the conductivity and flexibility of the resulting conductive printed silver film. When the ratio of Ag NPs to Ag flakes is maintained at 10:90, the volume resistivity of the Ag NPs-modified film registers at 2.7 × 10−5 Ω.cm. This demonstrates a substantial 53.45% reduction in the volume resistivity of the conductive printed silver film modified with Ag NPs, compared to its Ag NPs-absent counterpart. Post 200 cyclic bending tests, it becomes evident that the resistance change rate in the Ag NPs-modified conductive printed silver film is a mere 12.5%, whereas the Ag NPs-modified silver film lacking Ag NPs displays a resistance change rate of 21.5%. This discrepancy underscores the capacity of Ag NPs-modified Ag flakes to fortify the bending resistance of the conductive printed silver film. Comprehensive data analysis substantiates that the improvements in electrical conductivity and bending resistance can be attributed to the superior bridging facilitated by the sintering process on the surface of the Ag NPs-modified Ag flakes.