RESUMEN
Flexible electrochromic devices (FECDs) are widely explored for diverse applications including wearable electronics, camouflage, and smart windows. However, the manufacturing process of patterned FECDs remains complex, costly, and non-customizable. To address this challenge, a strategy is proposed to prepare integrated FECDs via multi-material direct writing 3D printing. By designing novel viologen/polyvinyl alcohol (PVA) hydrogel inks and systematically evaluating the printability of various inks, seamless interface integration can be achieved, enabling streamlined manufacturing of patterned FECDs with continuous production capabilities. The resultant 3D-printed FECDs exhibit excellent electrochromic and mechanical properties, including high optical contrast (up to 54% at 360 nm), nice cycling stability (less than 5% electroactivity reduction after 10 000 s), and mechanical stability (less than 19% optimal contrast decrease after 5000 cycles of bending). The potential applications of these 3D-printed hydrogel-based FECDs are further demonstrated in wearable electronics, camouflage, and smart windows.
RESUMEN
Low-cost fabric-based top-emitting polymer light-emitting devices (Fa-TPLEDs) have aroused increasing attention due to their remarkable potential applications in wearable displays. However, it is still challenging to realize efficient all-solution-processed devices from bottom electrodes to top electrodes with large-scale fabrication. Here, a smooth reflective Ag cathode integrated on fabric by one-step silver mirror reaction and a composite transparent anode of polydimethylsiloxane/silver nanowires/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) via a water-assisted peeling method are presented, both of which possess excellent optoelectrical properties and robust mechanical flexibility. The Fa-TPLEDs are constructed by spin-coating functional layers on the bottom reflective cathodes and laminating the top transparent anodes. The Fa-TPLEDs show a current efficiency of 16.3 cd A-1 , an external quantum efficiency of 4.9% and angle-independent electroluminescence spectra. In addition, the Fa-TPLEDs possess excellent mechanical stability, maintaining a current efficiency of 14.3 cd A-1 after 200 bending cycles at a radius of 4 mm. The results demonstrate that the integration of solution-processed reflective cathodes and transparent anodes sheds light on a new avenue to construct low-cost and efficient fabric-based devices, showing great potential applications in emerging smart flexible/wearable electronics.
RESUMEN
Light-emitting fibers have been intensively developed for the realization of textile displays and various lighting applications, as promising free-form electronics with outstanding interconnectivity. These advances in the fiber displays have been made possible by the successful implementation of the core technologies of conventional displays, including high optoelectronic performance and essential elements, in the fiber form-factor. However, although white organic light-emitting diodes (WOLEDs), as a fundamental core technology of displays, are essential for realizing full-color displays and solid-state lighting, fiber-based WOLEDs are still challenging due to structural issues and the lack of approaches to implementing WOLEDs on fiber. Herein, the first fiber WOLED is reported, exhibiting high optoelectronic performance and a reliable color index, comparable to those of conventional planar WOLEDs. As key features, it is found that WOLEDs can be successfully introduced on a cylindrical fiber using a dip-coatable single white-emission layer based on simulation and optimization of the white spectra. Furthermore, to ensure durability from usage, the fiber WOLED is encapsulated by an Al2 O3 /elastomer bilayer, showing stable operation under repetitive bending and pressure, and in water. This pioneering work is believed to provide building blocks for realizing complete textile display technologies by complementing the lack of the core technology.
RESUMEN
Advances in material science and nanotechnology have fostered the miniaturization of devices. Over the past two decades, the form-factor of these devices has evolved from 3D rigid, volumetric devices through 2D film-based flexible electronics, finally to 1D fiber electronics (fibertronics). In this regard, fibertronic strategies toward wearable applications (e.g., electronic textiles (e-textiles)) have attracted considerable attention thanks to their capability to impart various functions into textiles with retaining textiles' intrinsic properties as well as imperceptible irritation by foreign matters. In recent years, extensive research has been carried out to develop various functional devices in the fiber form. Among various features, lighting and display features are the highly desirable functions in wearable electronics. This article discusses the recent progress of materials, architectural designs, and new fabrication technologies of fiber-shaped lighting devices and the current challenges corresponding to each device's operating mechanism. Moreover, opportunities and applications that the revolutionary convergence between the state-of-the-art fibertronic technology and age-long textile industry will bring in the future are also discussed.
RESUMEN
Fiber-based wearable displays, one of the most desirable requisites of electronic textiles (e-textiles), have emerged as a technology for their capability to revolutionize textile and fashion industries in collaboration with the state-of-the-art electronics. Nonetheless, challenges remain for the fibertronic approaches, because fiber-based light-emitting devices suffer from much lower performance than those fabricated on planar substrates. Here, we report weavable and highly efficient fiber-based organic light-emitting diodes (fiber OLEDs) based on a simple, cost-effective and low-temperature solution process. The values obtained for the fiber OLEDs, including efficiency and lifetime, are similar to that of conventional glass-based counterparts, which means that these state-of-the-art, highly efficient solution processed planar OLEDs can be applied to cylindrical shaped fibers without a reduction in performance. The fiber OLEDs withstand tensile strain up to 4.3% at a radius of 3.5 mm and are verified to be weavable into textiles and knitted clothes by hand-weaving demonstrations. Furthermore, to ensure the scalability of the proposed scheme fiber OLEDs with several diameters of 300, 220, 120, and 90 µm, thinner than a human hair, are demonstrated successfully. We believe that this approach, suitable for cost-effective reel-to-reel production, can realize low-cost commercially feasible fiber-based wearable displays in the future.