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- 2018
- Flexible display
- fabrication process
- electrowetting
- PEN substrate
- Optoelectronic Information Science and Engineering
- South China Normal University
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Thermal and optical properties of high-density GaN micro-LED arrays on flexible substrates
摘要: Flexible GaN-based micron-size light-emitting diodes (μLEDs) with high brightness and low power-consumption are a promising technology for next-generation wearable displays. While, integrating GaN μLEDs onto flex can provide more functionality, the bending-induced strain and potential self-heating of the device are the challenges that degrade the device performance on plastic platforms. Here, a novel “paste-and-cut” approach to selectively transfer GaN μLEDs from sapphire substrates onto flexible platforms demonstrated the effectiveness of various intermediate metallic-bonding layers and LED geometries on the optical properties and performance of the flexible devices. Computational thermal simulation of the flexible μLEDs showed effective heat dissipation for devices mounted on plastic platforms bonded using a 0.5 μm thick Cu metallic pad to create stable optical emission (λ = 450 nm) under current densities of > 1 A/cm2. Through a finite-element analysis (FEA), it was determined that the applied stress-induced strain near the quantum wells of the μLEDs can be negligible for devices with diameters smaller than 20 microns. Experimental verification supported the simulation results; the diodes were found to be electrically and thermally stable when copper electrode layers > 600 nm thick was used to bond the LEDs onto the plastic platforms. The I-V characteristics of the μLEDs showed no measurable degradation after transfer onto the flexible substrate with a turn-on voltage of 2.5 V. Commensurate to the FEA simulations, no measurable optical wavelength shift was observed for LED having a diameter of 20 microns when driven at a current density of 1 A/cm2 under different mechanical strain.
关键词: Flexible Display,Heat Transfer,Invariant Emission,GaN Micro-LED
更新于2025-09-23 15:21:01
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Suppression of Ag migration by low-temperature sol-gel zinc oxide in the Ag nanowires transparent electrode-based flexible perovskite solar cells
摘要: Silver nanowires (Ag NWs) network is an excellent candidate as flexible transparent electrode applying in flexible perovskite solar cells, owing to their excellent electrical and optical properties. However, several problems including large surface roughness, chemical reaction between Ag and perovskite precursor, and migration of Ag limited the application in high performance perovskite solar cells. Aiming to solve these problems, the composite electrode combining the spray coated Ag nanowires and the low-temperature sol-gel zinc oxide was developed in this work. The optimized concentration and annealing temperature of sol-gel ZnO were 0.45 M and 150°C. The introduction of zinc oxide with suitable concentration caused slight impact on the transmittance and sheet resistant of transparent composite electrode, and promoted mechanical and chemical stability in air relative to the pristine Ag NWs electrode. The use of the composite flexible electrode could decrease the surface roughness of the Ag NWs electrode, passivate the reaction of perovskite and silver electrode, and prevent the migration of Ag. As a consequence, the performance of the flexible device significantly improved from 9.51% to 13.12%. Under the AM 1.5G constant illumination, the optimization device has a remarkably improved stability than pristine device. This study demonstrates that spray Ag NWs as bottom electrode is suitable for flexible perovskite solar cells. Meanwhile, it’s an effective method using sol-gel ZnO to construct composite electrode to promote the device performance and stability.
关键词: Ag nanowire electrode,Ag migration,Flexible perovskite solar cells,Sol-gel ZnO,Bending resistance
更新于2025-09-23 15:21:01
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Growth control and defect passivation toward efficient and low-temperature processed carbon based CsPbIBr2 solar cell
摘要: All-inorganic perovskite CsPbIBr2, has drawn much attention for photovoltaic (PV) application due to its excellent intrinsic stability. However, low device performance and high fabrication temperature still hamper its further progress in flexible application. Herein, Zn substitution has been used to improve the nucleation and growth process for low temperature processed a-phase CsPbIBr2 film. Zn incorporated CsPbIBr2 film exhibits good crystallinity, compact surface morphology and depressed defect state. Low temperature (100 and 160°C) processed carbon based CsPbIBr2 solar cells with improved PV performance have been prepared by using Zn incorporation and room deposited electron transport layer (ETL). A champion efficiency over 9% can be achieved through Zn substitution, which is one of the best values reported for the low temperature processed CsPbIBr2 solar cell without using hole transport layer (HTL). Efficiency over 5% can also be achieved for larger area (1 cm2) rigid and flexible CsPbIBr2 solar cells. These results would provide a new route for preparing high-performance and low temperature processed inorganic perovskite solar cell.
关键词: Carbon electrode,CsPbIBr2,Flexible,Solar cell,Low temperature,Inorganic perovskite
更新于2025-09-23 15:21:01
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Light trapping induced flexible wrinkled nanocone SERS substrate for highly sensitive explosive detection
摘要: We reported an ultrasensitive TNT detection method via a novel light trapping induced wrinkled nanocone flexible SERS substrate, which was fabricated by colloidal lithography and oxygen plasma etching on transparent PET film. Especially, a set of nanowrinkles with 50-60nm was found on the sidewall of nanocone after etching. By coating 30nm gold film, this flexible SERS substrate provided uniform hot spots, which demonstrated high reproducibility and sensitivity. 4-ATP molecules based Meisenheimer complex, which is a well-known charge-transfer interaction between electron-poor TNT and electron-rich amino group, was taken to detect ultra-low concentration of TNT explosive. The Raman signal of TNT was significantly enhanced by charge-transfer, light trapping effect and coupled electromagnetic field. The detection sensitivity of TNT molecules was as low as 10-13mol/L, and show a good linear response in the range from 10-8 to 10-13mol/L. Consequently, by brushing this flexible SERS substrate onto a cloth bag, trace amount of TNT residues with concentration as low as 10-10mol/L can be easily analyzed. It is believed that the proposed highly sensitive and uniform flexible substrate provides a significant solution for trace analysis of TNT residue in criminal forensic, military and security check.
关键词: Nanowrinkle,Nanocone,Flexible materials,Light trapping,SERS
更新于2025-09-23 15:21:01
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Lens-less PSD measurement of flexible link deflection
摘要: Accurate measurement of change in tip position and orientation of flexible links is of substantial importance for flexible robot control applications. In this paper, a measurement system is proposed to measure the change in position and orientation at the tip of a link subjected to bending and torsion with the use of PSD (Position Sensitive Detector) sensors for space applications. Contrary to existing methods on measuring the spatial deflection of a flexible robot, the proposed method eliminates the requirement of a fragile lens or prism to obtain the angular displacement when PSD sensors are used. Experimental results for measuring five variables are presented for a cantilever flexible link when subjected to bending and torsion under a static load, thereby demonstrating the effectiveness of the proposed method.
关键词: Optical Measurement,Position Sensitive Detector,Flexible Robotic Link,Laser Diode
更新于2025-09-23 15:21:01
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Flexible Electronics: Stretchable Electrodes and Their Future
摘要: Flexible electronics, as an emerging and exciting research field, have brought great interest to the issue of how to make flexible electronic materials that offer both durability and high performance at strained states. With the advent of on-body wearable and implantable electronics, as well as increasing demands for human-friendly intelligent soft robots, enormous effort is being expended on highly flexible functional materials, especially stretchable electrodes, by both the academic and industrial communities. Among different deformation modes, stretchability is the most demanding and challenging. This review focuses on the latest advances in stretchable transparent electrodes based on a new design strategy known as kirigami (the art of paper cutting) and investigates the recent progress on novel applications, including skin-like electronics, implantable biodegradable devices, and bioinspired soft robotics. By comparing the optoelectrical and mechanical properties of different electrode materials, some of the most important outcomes with comments on their merits and demerits are raised. Key design considerations in terms of geometries, substrates, and adhesion are also discussed, offering insights into the universal strategies for engineering stretchable electrodes regardless of the material. It is suggested that highly stretchable and biocompatible electrodes will greatly boost the development of next-generation intelligent life-like electronics.
关键词: kirigami,e-skins,soft robotics,stretchable transparent electrodes,flexible electronics
更新于2025-09-23 15:21:01
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Ultrahigh Conductivity and Superior Interfacial Adhesion of a Nanostructured, Photonic Sintered Copper Membrane for Printed Flexible Hybrid Electronics
摘要: Inkjet-printed electronics using metal particles typically lack electrical conductivity and interfacial adhesion with an underlying substrate. To address the inherent issues of printed materials, this paper introduces advanced materials and processing methodologies. Enhanced adhesion of the inkjet-printed copper (Cu) on a flexible polyimide film is achieved by using a new surface modification technique, a nanostructured self-assembled monolayer (SAM) of (3-mercaptopropyl)trimethoxysilane. A standardized adhesion test reveals the superior adhesion strength (1192.27 N/m) of printed Cu on the polymer film, while maintaining extreme mechanical flexibility proven by 100,000 bending cycles. In addition to the increased adhesion, the nanostructured SAM treatment on printed Cu prevents formation of native oxide layers. Combined with newly synthesized Cu ink and associated sintering technique with an intense pulsed ultraviolet and visible light absorption, it enables ultrahigh conductivity of printed Cu (2.3 x 10-6 ??cm), which is the highest electrical conductivity reported to date. The comprehensive materials engineering technologies offer highly reliable printing of Cu patterns for immediate use in wearable flexible hybrid electronics. In vivo demonstration of printed, skin-conformal Cu electrodes indicates a very low skin-electrode impedance (< 50 k?) without a conductive gel and successfully measures three types of biopotentials, including electrocardiograms, electromyograms, and electrooculograms.
关键词: Photonic sintering,Printed Cu membrane,Enhanced conductivity,Interfacial adhesion,Flexible hybrid electronics
更新于2025-09-23 15:21:01
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai, China (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - A stretchable translucent conductive film based on polymer microspheres lithography technology
摘要: Transparent and translucent conductor has played an important role in various of photoelectric device electrodes, including photovoltaics (PVs), light-emitting diodes (LEDs), liquid-crystal displays (LCDs), touch-screen panels (TSPs), and radiofrequency identification (RFID) and so on [1, 2]. Some conductive oxides are transparent but do not stretchable. We have confirmed a method based on polystyrene (PS) microspheres to obtain a stretchable transparent conductive film. The homogeneous mono-layer PS microstructure arrays were self-assembled on surface of modified polydimethylsiloxane (PDMS) film, and then the size and spacing distance of the microspheres were adjusted by plasma etching technology to obtain non-closed PS arrays, and the magnetron sputtering technology was used to deposit a layer of conductive metal on the etched microsphere arrays. The stretchable translucent conductive films show relatively high transmittance (53% at 550 nm), and good electrical stability under stretching conditions. They also posses better conformability and conformal on complex curve surfaces than conventional bendable transparent conductive films, and present excellent potential application in flexible electronic and biomedicine fields.
关键词: Stretchable,Polymer microsphere lithography,Self-assembly,Flexible optoelectronics,translucent conductors
更新于2025-09-23 15:21:01
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[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Inkjet Printed Parallel Plate Capacitors Using PVP Polymer Dielectric Ink on Flexible Polyimide Substrates
摘要: Inkjet printing (IJP) is an exciting new additive manufacturing technology that promises monolithic electronic circuit fabrication of μm thin low-cost large-area electronic low-cost body-worn flexible sensors. In this work, we demonstrate inkjet printed multilayer metal-dielectric-metal capacitors on flexible polyimide (PI) substrate by formulating a custom dielectric ink based on Poly 4-vinylphenol (PVP). Silver nanoparticle ink was used for printing the conductive parallel metal plates. We also demonstrate control over the capacitance values by varying the design parameters and succeeded in printing capacitors in the range 8.8 pF to 467 pF, with excellent repeatability on flexible PI substrates. A functional LC circuit using these printed capacitors has been designed and demonstrated to have a resonance frequency of 24.3 MHz. These results are a vital step forward towards monolithic printing of flexible electronic circuits using IJP technique for many applications such as body-worn sensors.
关键词: Inkjet printing,PVP dielectric ink,flexible electronics,polyimide substrate,capacitors
更新于2025-09-23 15:21:01
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Flexible nonvolatile resistive switching memory devices based on Bi<sub>2</sub>Te<sub>3</sub> nanosheets films
摘要: Flexible nonvolatile resistive switching memory is a promising candidate for next generation storage technologies. Exploring new materials is of crucial importance to achieve further performances of flexible nonvolatile resistive switching memory. In this work, topological insulator bismuth telluride (Bi2Te3) nanosheets films were introduced into firstly, a typical sandwich construction of Ag/Bi2Te3/indium tin oxide/polyethylene terephthalate with good flexibility, which exhibits nonvolatile bipolar resistive switching characteristics of operation voltage, good mechanical flexibility, and good storage stability. Furthermore, trap-controlled space charge limited current, thermionic emission are the dominant conduction mechanisms in the carrier transport. This work will provide an opportunity for Bi2Te3 nanosheets to be used in flexible electronics application.
关键词: Resistive switching,Bismuth telluride,Flexible memory,Nonvolatile,Filtration
更新于2025-09-23 15:21:01