Conductivity Of Films Research Articles

Air-Processed Perovskite Solar Cells with >25% Efficiency and High Stability Enabled by Crystallization Modulation and Holistic Passivation.

Organic semiconductors (e.g., PCBM and IDIC) frequently serve as interface passivants for perovskite solar cells (PSCs) due to their beneficial passivation effects on perovskite interfaces. However, their passivation to the interiors of perovskite films is greatly limited by their poor solubility in polar solvents and compatibility issues. Here the facile synthesis of organic semiconductor nanoparticle (NP) passivants that readily disperse in perovskite inks is reported. Adding these NPs into perovskite inks not only modulates perovskite crystallization, improves film quality and conductivity, but also achieves holistic bulk film passivation. Consequently, blade-coated p-i-n PSCs with ICBA NPs achieve an impressive efficiency of 25.1% (independently certified as 25.0%), the highest reported value for air-processed PSCs irrespective of fabrication methods or device structures. This work develops a novel approach for effective and holistic perovskite passivation by converting conventional passivants to perovskite-compatible NPs, paving the way for more efficient and stable perovskite solar devices.

Organic Mixed Ionic Electronic Conductor Nanochannels for Vertical Electrochemical and Ionic Transistors

AbstractThin films of organic mixed ionic electronic conductors (OMIECs) constitute the functional layer in organic electrochemical transistors (OECTs), organic bioelectronic transducers and other ionic‐electronic devices. The thin‐film configuration constrains devices to be fabricated on impermeable substrates in the form of 2D microstructures with lateral electrodes to drive an electronic current through the thin film. In order to alleviate such constraints, novel OMIEC deposition methods are needed that produce alternatives to thin‐film devices and that are compatible with permeable substrates and electronic transport in the vertical direction. Here OMIECs filled nanoporous membranes are introduced as functional layer in devices with mixed ionic electronic transport. Electropolymerization of ethylenedioxythiophene (EDOT) monomers is used to fabricate OMIEC filled nanochannels. Electronic and ionic transport through such nanochannels are investigated and modulation of electronic as well as ionic carrier density by action of a third gate electrode is demonstrated. The novel OMIEC nanochannels enable the fabrication of vertical OECTs with high transconductance and organic ionic transistors using only additive fabrication methods.

Studies of optoelectrical properties of Mn-doped ZnO nanostructure for supercapacitor and photodetector applications

The transition metal Manganese (Mn)-doped Zinc Oxide (ZnO) nanoparticles were synthesized using the sol-gel method. The nanomaterials ZnO and Zn1-xMnxO (x=0–0.15) formation, their crystal structure, and morphological properties were confirmed by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) analysis of the materials. All the studied materials show hexagonal wurtzite structure with the particle size in nanometres. The optical properties of transition metal Mn-doped ZnO nanomaterials were explored by the absorption and transmission spectra. The band gap of the nanomaterials decreases with the increase of Mn doping concentration from 3.01 to 3.26 eV. The mobility and electrical conductivity of the Mn-doped ZnO thin films show a decreasing trend with the increase of Mn doping concentration in ZnO. The Mn-doped materials were investigated for supercapacitor and photodiode applications. The Zn0.90Mn0.10O nanomaterials show the maximum specific capacitance, power and energy density of ∼ 220 F/g, 2202 W/kg and 1.15 Wh/kg, respectively. The electrochemical properties confirm that the doping of ZnO opens a new window for its application in energy storage devices. The ZnO and Mn-doped ZnO were used as an electron transport layer in perovskite MAPbI3 photodiodes. Under the Illumination of blue (465 nm) light, the highest detectivity of undoped ZnO perovskite photodiode is ∼4.5×1010 Jones and doped ZnO perovskite photodiode is 0.7×1010 Jones, respectively. The low mobility of charges and unfavorable energy level alignment of Mn-doped ZnO with MAPbI3 thin films is the reason for the decrease in photo detectivity. Our studies demonstrate that the Mn-doped ZnO nanomaterials and their thin films have avenues for potential application in energy storage devices and photodiodes of perovskite MAPbI3.

Preparation of PEDOT flexible transparent conductive film by Solution shear method for OLEDs

In this work, the large-area poly 3,4-ethylenedioxythiophene (PEDOT: PSS) transparent conductive films (TCFs) were prepared by the solution shear method. These films exhibited excellent bendability, strong adhesion, superior uniformity, and high-light transmission. The optimum photoelectric figure of merit (FoM) of the films was 195.5, and the optimum photoelectric performance at a low sheet resistance (< 50 Ω/sq) was observed in the three-layer films, which was prepared at a dilution ratio of 2:1 and a shear rate of 1 mm/s, showing a thin-layer resistance of 34.7 Ω/sq, a transmittance of 93.2 %, an FoM of 151.9 and electrical conductivity of 2398.6 S/cm. The prepared films were used as the organic light-emitting diode (OLED) anode, and the large-area flexible green OLED device with good uniformity was obtained. The maximum current efficiency of the prepared large-area flexible OLED was 2.16 cd/A, reflecting the great potential of this solution-shear film in the field of flexible devices.

Two-step modification strategy enhances carbon fiber/old corrugated container fiber flexible conductive film

Carbon fiber (CF) possesses inherent properties of low density, high strength, and environmental stability. Its high aspect ratio and knittability enable the formation of flexible conductive networks. Old corrugated container (OCC) is rich in cellulose and hemicellulose, rendering them flexible and exhibiting a low coefficient of thermal expansion. In this paper, CF/OCC/PVA flexible conductive films were prepared using polyvinyl alcohol (PVA) as the matrix, CF as the conductive filler and OCC as the flexible support material. Firstly, the coupling agent was grafted on the surface of CF to enhance their surface activity, improve the dispersion of CF in solution and the chemical bonding of CF to the matrix. Subsequently, sizing nanoparticles were applied to increase the roughness of the CF surface. This served to increase the volume of the conductive network and enhance the mechanical interlocking between CF and PVA. The results show that the two-step combined modification strategy have a significant positive impact on the interfacial chemical activity, contact angle, and roughness of CF. Moreover, it leads to notable improvements in various properties of the conductive film materials. This finding is relevant for the preparation of CF reinforced other matrix materials as well as for expanding the special properties and application value of CF conductive thin film materials.

Fabrication of highly flexible, wearable, free-standing symmetric supercapacitors with high voltage operation enabled by hierarchical graphene/cerium oxide/polypyrrole hybrid films

Flexible, free-standing supercapacitors play a significant role in the development of future wearable energy storage devices. Herein, we successfully fabricated the highly flexible and free-standing graphene/cerium oxide/polypyrrole hybrid films by thermal reduction of graphene oxide (GO) followed by the sol–gel synthesis of CeO2 and then the addition of PPy. By regulating oxygen functional groups in GO, the electronic conductivity and electroactive sites of the hybrid films are significantly controlled, leading to enhanced energy storage capability. Finally, a symmetric flexible supercapacitor (FSC) device was developed using the prepared films as electrodes. Resulting, the integrated symmetric GO-400/CeO2/PPy FSC manifests excellent areal capacitance of 49.0 mF cm−2 at 1 mA cm−2, with a durability of 83.1 % over 10,000 cycles. Specifically, the FSC exhibited capacitance retention of 77.2 % after 10,000 cycles under bending state with exceptional rate ability. Meanwhile, an impressive energy density of 19.69 µW h cm−2 was attained at a power density of 0.85 mW cm−2. Evidently, the synergistic interactions between GO and PPy nanosheets, along with CeO2 favour the rapid electron movement of electrode material for next-generation wearable, portable electronics.

Facile design of structurally robust, highly conductive and well-flexible hybrid film based on MXene, cellulose nanofiber and poly (3,4-ethylenedioxythiphoenes):polystyrene sulfonate for supercapacitors

Robust, conductive and flexible electrode materials have been the focus of attention in portable, wearable electronics. However, it is still a significant challenge to achieve synergistic development of multiple properties simultaneously. Herein, we propose a combination of microscale design and nanostructures strategy to prepare MXene/cellulose nanofiber-poly (3,4-ethylenedioxythiphoenes):polystyrene sulfonate (Ti3C2Tx/CNF-PEDOT:PSS, TC-P) hybrid film by a simple in-situ polymerization and vacuum filtration process. CNF serves as the supporting skeleton of PEDOT:PSS, effectively mitigating its self-aggregation and structural deformation due to the expansion/contraction of the polymer network. And the CNF-PEDOT:PSS composite is capable to open up the interlayer space of Ti3C2Tx, which reduces the self-stacking of Ti3C2Tx nanosheets. The strong interactions among the three components enable the hybrid film electrode to possess both flexibility and high electrochemical properties. As a result, the film electrode exhibits a remarkable tensile strength of 77.4 MPa and an excellent conductivity of 162.5 S cm−1, as well as an outstanding areal specific capacitance of 896 mF cm−2 at 4 mA cm−2. Moreover, the assembled symmetric supercapacitor (SSC) device displays a large areal energy density of 62 µWh cm−2 at a power density of 800 µW cm−2 and demonstrates a long cycle life with 85.1 % capacitance retention after 10,000 GCD cycles. This study provides an effective strategy to balance mechanical flexibility and electrochemical properties, providing an inspiration to prepare flexible electrodes that are widely applied in a new generation of portable, wearable electronics.

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 (&lt;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.