Search Results (1,183)

This study explores the potential of copper-doped nickel oxide (Cu:NiO) as a hole transport layer (HTL) in flexible photovoltaic (PV) devices using a combined first-principles and finite element analysis approach. Density functional theory (DFT) calculations reveal that Cu doping introduces additional states in the valence band of NiO, leading to enhanced charge transport. Notably, Cu:NiO exhibits a direct band gap (reduced from 3.04 eV in NiO to 1.65 eV in the stable supercell structure), facilitating the efficient hole transfer from the active layer. Furthermore, the Fermi level shifts towards the valence band in Cu:NiO, promoting hole mobility. This translates to an improved photovoltaic performance, with Cu:NiO-based HTLs achieving ~18% and ~9% power conversion efficiencies (PCEs) in perovskite and poly 3-hexylthiophene: 1-3-methoxycarbonyl propyl-1-phenyl 6,6 C 61 butyric acid methyl ester (P3HT:PCBM) polymer solar cells, respectively. Finally, a finite element analysis demonstrates the potential of these composite HTLs with Poly 3,4-ethylene dioxythiophene)—polystyrene sulfonate (PEDOT:PSS) in flexible electronics design and the optimization of printing processes. Overall, this work highlights Cu:NiO as a promising candidate for high-performance and flexible organic–inorganic photovoltaic cells. Full article

Polyimide (PI) films are well recognized for their outstanding chemical resistance, radiation resistance, thermal properties, and mechanical strength, rendering them highly valuable in advanced fields such as aerospace, sophisticated electronic components, and semiconductors. However, improving their optical transparency while maintaining excellent thermal properties remains a significant challenge. This review systematically checks over recent advancements in enhancing the optical and thermal performance of PI films, focusing on various strategies through molecular design. These strategies include optimizing the main chain, side chain, non-coplanar structures, and endcap groups. Rigid and flexible structural characteristics in the proper combination can contribute to the balance thermal stability and optical transparency. Introducing fluorinated substituents and bulky side groups significantly reduces the formation of charge transfer complexes, enhancing both transparency and thermal properties. Non-coplanar structures, such as spiro and cardo configurations, further improve the optical properties while maintaining thermal stability. Future research trends include nanoparticle doping, intrinsic microporous PI polymers, photosensitive polyimides, machine learning-assisted molecular design, and metal coating techniques, which are expected to further enhance the comprehensive optical and thermal performance of PI films and expand their applications in flexible displays, solar cells, and high-performance electronic devices. Overall, systematic molecular design and optimization have significantly improved the optical and thermal performance of PI films, showing broad application prospects. This review aims to provide researchers with valuable references, stimulate more innovative research and applications, and promote the deep integration of PI films into modern technology and industry. Full article

Flexible organic solar cells (FOSCs) represent a promising and rapidly evolving technology, characterized by lightweight construction, cost-effectiveness, and adaptability to various shapes and sizes. These advantages render FOSCs highly suitable for applications in diverse fields, including wearable electronics and building-integrated photovoltaics. The application scope of FOSCs necessitates electrodes with properties such as high optical transmittance, low electrical resistivity, and exceptional mechanical strength, where their selection significantly influences the overall device performance. This review explores several materials, focusing on polymers, carbon nanomaterials, and metal nanowires, highlighting their unique advantages and challenges in FOSC applications. Through this thorough review, we would like to elucidate the relationship between electrode materials and device performance, thereby inspiring further improvements and developments in FOSCs and broadening their application range. Full article

Two-dimensional (2D) semiconductors have attracted much attention regarding their use in flexible electronic and optoelectronic devices, but the inherent poor electron mobility in conventional 2D materials severely restricts their applications. Using first-principles calculations in conjunction with Boltzmann transport theory, we systematically investigated the Si-doped 2D β-Ga₂O₃ structure mediated by biaxial strain, where the structural stabilities were determined by formation energy, phonon spectrum, and ab initio molecular dynamic simulation. Initially, the band gap values of Si-doped 2D β-Ga₂O₃ increased slightly, followed by a rapid decrease from 2.46 eV to 1.38 eV accompanied by strain modulations from −8% compressive to +8% tensile, which can be ascribed to the bigger energy elevation of the σ* anti-bonding in the conduction band minimum than that of the π bonding in the valence band maximum. Additionally, band structure calculations resolved a direct-to-indirect transition under the tensile strains. Furthermore, a significantly high electron mobility up to 4911.18 cm² V⁻¹ s⁻¹ was discovered in Si-doped 2D β-Ga₂O₃ as the biaxial tensile strain approached 8%, which originated mainly from the decreased quantum confinement effect on the surface. The electrical conductivity was elevated with the increase in tensile strain and the enhancement of temperature from 300 K to 800 K. Our studies demonstrate the tunable electron mobilities and band structures of Si-doped 2D β-Ga₂O₃ using biaxial strain and shed light on its great potential in nanoscale electronics. Full article

This work presents the synthesis of para-quinone methides (p-QMs), which were deposited as films using the high vacuum sublimation technique after being chemically characterized. The p-QMs films were characterized morphologically and structurally using scanning electron microscopy, atomic force microscopy, and X-ray diffraction. In addition, their optical behavior was studied by means of ultraviolet–visible spectroscopy, and the optical gaps obtained were in the range of 2.21–2.71 eV for indirect transitions, indicating the semiconductor behavior of the p-QMs. The above was verified through the manufacture and evaluation of the electrical behavior of rigid semiconductor devices, in which fluorine-doped tin oxide-coated glass slides (FTO) were used as an anode and substrate. Finally, as an original, ecological, and low-cost application, the FTO was replaced by substrates and anodes made from recycled Tetra Pak^®, generating flexible semiconductor devices. Although the electrical current transported depends on the type of p-QMs, the substituent in its structure, and the morphology, the kinds of substrate and anode also influence the type of electrical behavior of the device. This current–voltage study demonstrates that p-QM2 with 4-Cl-Ph as a radical, p-QM3 with 4-Et₂N-Ph as a radical, and p-QM6 with 5-(1,3-benzodioxol) as a radical can be used in optoelectronics as semiconductor films. Full article

Studying the electromechanical response behavior of piezoelectric thin films under different loading conditions is of great value for the development and optimization of piezoelectric sensors and flexible portable electronic devices. This paper establishes the theory of large deflection vibration of rectangular four-edge simply supported piezoelectric thin films using the energy method, and analyzes the electromechanical response characteristics of vibration force (including resonant frequency and nonlinear vibration). Meanwhile, the electromechanical response behavior of Poly(vinylidene fluoride) (PVDF) films under different loading conditions (static and harmonic vibration) is analyzed. The study investigates the nonlinear vibration characteristics and resonance frequency variations under different film sizes and thickness conditions in the case of various loading conditions. The developed model can predict the resonance frequency associated with the plate dimensions. This study is of great significance for the research and application of laminated piezoelectric film sensors. Full article

Organic solar cells (OSCs) are considered a very promising technology to convert solar energy to electricity and a feasible option for the energy market because of the advantages of light weight, flexibility, and roll-to-roll manufacturing. They are mainly characterized by a bulk heterojunction structure where a polymer donor is blended with an electron acceptor. Their performance is highly affected by the design of donor–acceptor conjugated polymers and the choice of suitable acceptor. In particular, benzotriazole, a typical electron-deficient penta-heterocycle, has been combined with various donors to provide wide bandgap donor polymers, which have received a great deal of attention with the development of non-fullerene acceptors (NFAs) because of their suitable matching to provide devices with relevant power conversion efficiency (PCE). Moreover, different benzotriazole-based polymers are gaining more and more interest because they are considered promising acceptors in OSCs. Since the development of a suitable method to choose generally a donor/acceptor material is a challenging issue, this review is meant to be useful especially for organic chemical scientists to understand all the progress achieved with benzotriazole-based polymers used as donors with NFAs and as acceptors with different donors in OSCs, in particular referring to the PCE. Full article

The focus of the study in this article is analyzing the electrochemical properties of molybdenum disulfide on miscible poly(methyl methacrylate)-poly(lactic acid) blends for supercapacitors. The interaction between molybdenum disulfide and miscible poly(methyl methacrylate)-poly(lactic acid) blends, affinity toward water, surface morphology, and mechanical properties are inspected by Fourier transform infrared spectroscopy, water contact angle, scanning electron microscopy, and universal testing machine, respectively. Among the developed membranes, 0.75 wt% of molybdenum disulfide on poly(methyl methacrylate)-poly(lactic acid) shows better electrochemical performances. It exhibits a maximum specific capacitance of 255.5 F g⁻¹ at a current density of 1.00 mA g⁻¹, maximum energy density of 22.7 Wh kg⁻¹, and maximum power density of 360 W kg⁻¹. A cycle study reveals 92% capacitance retention after 2500 cycles. The designed supercapacitor device shows a maximum specific capacitance of 1240 μF g⁻¹ at a current density of 0.5 μA g⁻¹, maximum energy density of 43 μWh kg⁻¹, and maximum power density of 700 μW kg⁻¹. Flexible membranes of molybdenum disulfide are expected to be a potent combination for supercapacitor applications. Full article

Nowadays, additive manufacturing technologies have impacted different engineering sectors. Three- and four-dimensional printing techniques are increasingly used in soft and flexible electronics thanks to the possibility of working contemporarily with several materials on various substrates. The materials portfolio is wide, as well as printing processes. Shape memory polymers, together with composites, have gained great success in the electronic field and are becoming increasingly popular for fabricating pH, temperature, humidity, and stress sensors that are integrated into wearable, stretchable, and flexible devices, as well as for the fabrication of communication devices, such as antennas. Here, we report an overview of the state of the art about the application of 4D printing technologies and smart materials in electronics. Full article

As microelectronics technology advances towards miniaturization and higher integration, the imperative for developing high-performance thermal management materials has escalated. Thermal conductive polymer composites (TCPCs), which leverage the benefits of polymer matrices and the unique effects of nano-enhancers, are gaining focus as solutions to overheating due to their low density, ease of processing, and cost-effectiveness. However, these materials often face challenges such as thermal conductivities that are lower than expected, limiting their application in high-performance electronic devices. Despite these issues, TCPCs continue to demonstrate broad potential across various industrial sectors. This review comprehensively presents the progress in this field, detailing the mechanisms of thermal conductivity (TC) in these composites and discussing factors that influence thermal performance, such as the intrinsic properties of polymers, interfacial thermal resistance, and the thermal properties of fillers. Additionally, it categorizes and summarizes methods to enhance the TC of polymer composites. The review also highlights the applications of these materials in emerging areas such as flexible electronic devices, personal thermal management, and aerospace. Ultimately, by analyzing current challenges and opportunities, this review provides clear directions for future research and development. Full article

With the gradual miniaturization of electronic devices and the increasing interest in wearable devices, flexible microelectronics is being actively studied. Owing to the limitations of existing battery systems corresponding to miniaturization, there is a need for flexible alternative power sources. Accordingly, energy harvesting from surrounding environmental systems using fluorinated polymers with piezoelectric properties has received significant attention. Among them, polyvinylidene fluoride (PVDF) and PVDF co-polymers have been researched as representative organo-piezoelectric materials because of their excellent piezoelectric properties, mechanical flexibility, thermal stability, and light weight. Electrospinning is an effective method for fabricating nanofibrous meshes with superior surface-to-volume ratios from polymer solutions. During electrospinning, the polymer solution is subjected to mechanical stretching and in situ poling, corresponding to an external strong electric field. Consequently, the fraction of the piezoelectric β-phase in PVDF can be improved by the electrospinning process, and enhanced harvesting output can be realized. An overview of electrospun piezoelectric fibrous meshes composed of PVDF or PVDF co-polymers to be utilized is presented, and the recent progress in enhancement methods for harvesting output, such as fiber alignment, doping with various nanofillers, and coaxial fibers, is discussed. Additionally, other applications of these meshes as sensors are reviewed. Full article

The development of thermally conductive polymer/boron nitride (BN) composites with excellent electrically insulating properties is urgently demanded for electronic devices. However, the method of constructing an efficient thermally conductive network is still challenging. In the present work, heterostructured multi-walled carbon nanotube-boron nitride (MWCNT-BN) hybrids were easily prepared using an electrostatic self-assembly method. The thermally conductive network of the MWCNT-BN in the thermoplastic polyurethane (TPU) matrix was achieved by the electrospinning and stack-molding process. As a result, the in-plane thermal conductivity of TPU composite films reached 7.28 W m⁻¹ K⁻¹, an increase of 959.4% compared to pure TPU films. In addition, the Foygel model showed that the MWCNT-BN hybrid filler could largely decrease thermal resistance compared to that of BN filler and further reduce phonon scattering. Finally, the excellent electrically insulating properties (about 10¹² Ω·cm) and superior flexibility of composite film make it a promising material in electronic equipment. This work offers a new idea for designing BN-based hybrids, which have broad prospects in preparing thermally conductive composites for further practical thermal management fields. Full article

Metasurface absorbers have shown significant potential in stealth applications due to their adaptability and capacity to reduce the backscattering of electromagnetic (EM) waves. Nevertheless, due to the materials used in the terahertz (THz) range, simultaneously achieving excellent stealth performance in ultrawideband remains an important and difficult challenge to overcome. In this study, an ultrawideband absorber is proposed based on indium tin oxide (ITO) and polyethylene-terephthalate (PET), with a structure thickness of only 0.16λ. ITO sheets are utilized to achieve broad-spectrum, optical transparency and flexibility of the metasurface. The results show that absorption higher than 90% can be achieved in the frequency band ranging from 1.75 to 5 THz under normal TE and TM polarizations, which covers a wide THz band. The structure is insensitive to polarization angles and exhibits 97% relative bandwidth above 90% efficiency up to an oblique incident angle of 60°. To further validate the efficiency of the absorption performance, the radar cross-section (RCS) reduction investigation was performed on both planar and conformal configurations. The findings show that under normal incidence EM waves, both flat and curved surfaces can achieve RCS reduction of over 10 dB, covering an extremely wide frequency range of 1.75 to 5 THz. The metasurface presented in this study exhibits significant potential for use in several THz applications, including flexible electronic devices and stealth aircraft windows. Full article

Flexible electronics have revolutionized the field by overcoming the rigid limitations of traditional devices, offering superior flexibility and adaptability. Conductive ink performance is crucial, directly impacting the stability of flexible electronics. While metal filler-based inks exhibit excellent conductivity, they often lack mechanical stability. To address this challenge, we present a novel conductive ink utilizing a ternary composite filler system: liquid metal and two micron-sized silver morphologies (particles and flakes). We systematically investigated the influence of filler type, mass ratio, and sintering process parameters on the composite ink’s conductivity and mechanical stability. Our results demonstrate that flexible wires fabricated with the liquid metal/micron silver particle/micron silver flake composite filler exhibit remarkable conductivity and exceptional bending stability. Interestingly, increasing the liquid metal content results in a trade-off, compromising conductivity while enhancing mechanical performance. After enduring 5000 bending cycles, the resistance change in wires formulated with a 4:1 mass ratio of micron silver particles to flakes is only half that of wires with a 1:1 ratio. This study further investigates the mechanism governing resistance variations during flexible wire bending. Additionally, we observed a positive correlation between sintering temperature and pressure with the conductivity of flexible wires. The significance of the sintering parameters on conductivity follows a descending order: sintering temperature, sintering pressure, and sintering time. Finally, we demonstrate the practical application of this technology by integrating the composite ink-based flexible wires with conductive polymer-based strain sensors. This combination successfully achieved the detection of human movements, including finger and wrist bending. Full article

Microstructures have been proved as crucial factors for the sensing performance of flexible pressure sensors. In this study, polypyrrole (PPy)/sunflower pollen (SFP) (P/SFP) was prepared via the in situ growth of PPy on the surface of degreased SFP with a sea urchin-like microstructure; then, these P/SFP microspheres were sprayed onto a flat silk cocoon (FSC) to prepare a sensing layer P/SFP-FSC. PPy-FSC (P-FSC) was prepared as an electrode layer through the in situ polymerization of PPy on the FSC surface. The sensing layer P/SFP-FSC was placed between two P-FSC electrode layers to assemble a P/SFP-FSC pressure sensor together with a fork finger electrode. With 6 mg/cm² of optimized sprayed P/SFP microspheres, the prepared flexible pressure sensor has a sensitivity of up to 0.128 KPa⁻¹ in the range of 0–13.18 KPa and up to 0.13 KPa⁻¹ in the range of 13.18–30.65 KPa, a fast response/recovery time (90 ms/80 ms), and a minimum detection limit as low as 40 Pa. This fabricated flexible P/SFP-FSC sensor can monitor human motion and can also be used for the encrypted transmission of important information via Morse code. In conclusion, the developed flexible P/SFP-FSC pressure sensor based on microstructure modification in this study shows good application prospects in the field of human–computer interaction and wearable electronic devices. Full article