Synergistic Effect of Cation Composition Engineering of Hybrid Cs1-x FAx PbBr3 Nanocrystals for Self-Healing Electronics Application.

Mixed-cation hybrid perovskite nanocrystal (HPNC) with high crystallinity, color purity, and tunable optical bandgap offers a practical pathway toward next-generation displays. Herein, a two-step modified hot-injection combined with cation compositional engineering and surface treatment to synthesize high-purity cesium/formamidinium lead bromide HPNCs(Cs1-x FAx PbBr3 ) is presented. The optimized Cs0.5 FA0.5 PbBr3 light-emitting devices (LEDs) exhibit uniform luminescence of 3500 cd m-2 and a prominent current efficiency of 21.5 cd A-1 . As a proof of concept, a self-healing polymer (SHP) integrated with white LED backlight and laser prototypes exhibited 4 h autonomous self-healing through the synergistic effect of weak reversible imine bonds and stronger H-bonds. First, the SHP-HPNCs-initial and SHP-HPNCs-cut possess high long-term stability and dramatically suppressed lead leakage as low as 0.6 ppm along with a low leakage rate of 1.11 × 10-5 cm2 and 3.36 × 10-5 cm2 even over 6 months in water. Second, the Cs0.5 FA0.5 PbBr3 HPNCs and SHP-induced shattered-repaired perovskite glass substrate show the lowest lasing threshold values of 1.24 and 8.58 µJ cm-2 , respectively. This work provides an integrative and in-depth approach to exploiting SHP with intrinsic and entropic self-healing capabilities combined with HPNCs to develop robust and reliable soft-electronic backlight and laser applications.

Red Disperse Azo Dye Side Chains Influence on Polyethylene Terephthalate Dyeing Performances in Supercritical Carbon Dioxide Media.

Supercritical carbon dioxide dyeing (SDD) as a dyeing media not only provides a friendly dyeing environment but also significantly increases polymeric dyeing performances ascribed to strong azo dye affinity. Disperse azo dyes have shown to be highly efficient dyeing agents due to their facile coupling synthesis, side chains position, and length tunability to optimize absorption properties. Herein, we first synthesize two series of disperse red azo dyes via a coupling chemical route. Further, we investigate the position of the electron withdrawing group and alkyl chains length impact onto the absorption and color fastness properties. Upon synthesis, 1H NMR and mass spectroscopy were used to characterize our newly synthesized series dye structure. Also, according to spectroscopic characterization, the functional group positions as well as the alkyl chains length have a major impact on the dye series maximum light absorption wavelength and performance. We have performed SDD dyeing of polyethylene terephthalate woven and determined each dye color fastness, we find that a reduced electron withdrawing effect and alkyl chains increase reduce color-fastness performances. Overall, our dyes exhibited a good resistance against detergent water, perspiration, abrasion, and friction.

Nanofiber-Based Odor-Free Medical Mask Fabrication Using Polyvinyl Butyral and Eucalyptus Anti Odor Agent.

Following the 2020 COVID-19 worldwide outbreak, many countries adopted sanitary and safety measures to safeguard public health such as wearing medical face mask. While face masks became a necessity for people, disadvantages impede their long period wearing such as uncomfortable breathability and odor. The intermediate layer of the medical face mask is composed of porous non-woven fabric to block external particles while maintaining breathability. To overcome aforementioned limitation, this study uses electrospinning to design and fabricate odorless face masks via the use of aromatic oil. Eucalyptus essential oil is encapsulated through mixing and layer-by-layer by hydrophobic polyvinyl butyral and further used to fabricate the medical mask intermediate layer. We found that adding 0.2 g of eucalyptus into polyvinyl butyral fabric through mixing results in the deodorization rate of 80% after 2 h, with fabric thickness of 440.9 µm, and melt-blown non-woven fabric thickness of 981.7 µm. The Particle Filtration Efficiency of 98.3%, Bacterial Filtration Efficiency above 99.9%, and the differential pressure of 4.7 mm H2O/cm2 meet the CNS 14774 standard on medical face masks. Therefore, this study successfully proved that this type of masks' middle layer not only effectively protects against coronavirus, but also provides better scents and makes it more comfortable for consumers.

Synthesis of Azo Disperse Dyes with High Absorption for Efficient Polyethylene Terephthalate Dyeing Performances in Supercritical Carbon Dioxide.

Supercritical carbon dioxide dyeing (SCDD) not only enables strong dyeing performance for a versatile range of polymer material but is also regarded as a green chemical media due to its low environmental impact as well as low risk of product denaturation. Over the decades, azo disperse dyes have been revealed to be efficient dyes and represent the wide majority of dyeing material. Azo dyes possess a wide variety of functional groups to optimize dye synthesis and tune the light absorption properties. Using SCDD, end-chain of different lengths, and functional group exhibiting various electronic affinity, six disperse red azo dyes were synthesized to investigate dyeing performances as woven fabric type, color strain, and color fastness after dyeing are discussed. Dye structure synthesized through a coupling reaction was confirmed by 1H NMR and mass spectroscopy. We found that the light absorption wavelength and absorption coefficient value variation are associated to the nature of the functional group. From the color strength values of the polyethylene terephthalate woven after dyeing, we find that the fiber host and dye dopant chemical structure greatly influence the dyeing process by providing enhanced woven, color strain, and color fastness. In comparison with commercial products, our approach not only improves the dyeing process but also guarantees a strong resistance of the dyed product against water, detergent, perspiration, abrasion, and friction.

Human Skin-Inspired Electrospun Patterned Robust Strain-Insensitive Pressure Sensors and Wearable Flexible Light-Emitting Diodes.

Wearable skin-inspired electronic skins present remarkable outgrowth in recent years because their promising comfort device integration, lightweight, and mechanically robust durable characteristics led to significant progresses in wearable sensors and optoelectronics. Wearable electronic devices demand real-time applicability and factors such as complex fabrication steps, manufacturing cost, and reliable and durable performances, severely limiting the utilization. Herein, we nominate a scalable solution-processable electrospun patterned candidate capable of forming ultralong mechanically robust nano-microdimensional fibers with higher uniformity. Nanofibrous patterned substrates present surface energy and silver nanoparticle crystallization shifts, contributing to strain-sensitive and -insensitive conductive electrodes (10 000 cycles of 50% strain). Synergistic robust stress releasing and durable electromechanical behavior engenders stretchable durable health sensors, strain-insensitive pressure sensors (sensitivity of ∼83 kPa-1 and 5000 durable cycles), robust alternating current electroluminescent displays, and flexible organic light-emitting diodes (20% improved luminescence and 300 flex endurance of 2 mm bend radius).

Super Tough and Spontaneous Water-Assisted Autonomous Self-Healing Elastomer for Underwater Wearable Electronics.

Self-healing soft electronic material composition is crucial to sustain the device long-term durability. The fabrication of self-healing soft electronics exposed to high moisture environment is a significant challenge that has yet to be fully achieved. This paper presents the novel concept of a water-assisted room-temperature autonomous self-healing mechanism based on synergistically dynamic covalent Schiff-based imine bonds with hydrogen bonds. The supramolecular water-assisted self-healing polymer (WASHP) films possess rapid self-healing kinetic behavior and high stretchability due to a reversible dissociation-association process. In comparison with the pristine room-temperature self-healing polymer, the WASHP demonstrates favorable mechanical performance at room temperature and a short self-healing time of 1 h; furthermore, it achieves a tensile strain of 9050%, self-healing efficiency of 95%, and toughness of 144.2 MJ m-3 . As a proof of concept, a versatile WASHP-based light-emitting touch-responsive device (WASHP-LETD) and perovskite quantum dot (PeQD)-based white LED backlight are designed. The WASHP-LETD has favorable mechanical deformation performance under pressure, bending, and strain, whereas the WASHP-PeQDs exhibit outstanding long-term stability even over a period exceeding one year in a boiling water environment. This paper provides a mechanically robust approach for producing eco-friendly, economical, and waterproof e-skin device components.

Improving the Performance and Stability of Perovskite Light-Emitting Diodes by a Polymeric Nanothick Interlayer-Assisted Grain Control Process.

CsPbBr3 is a promising light-emitting material due to its wet solution processability, high photoluminescence quantum yield (PLQY), narrow color spectrum, and cost-effectiveness. Despite such advantages, the morphological defects, unsatisfactory carrier injection, and stability issues retard its widespread applications in light-emitting devices (LEDs). In this work, we demonstrated a facile and cost-effective method to improve the morphology, efficiency, and stability of the CsPbBr3 emissive layer using a dual polymeric encapsulation governed by an interface-assisted grain control process (IAGCP). An eco-friendly low-cost hydrophilic polymer poly(vinylpyrrolidone) (PVP) was blended into the CsPbBr3 precursor solution, which endows the prepared film with a better surface coverage with a smoothened surface. Furthermore, it is revealed that inserting a thin PVP nanothick interlayer at the poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS)/emissive layer interface further promotes the film quality and the performance of the derived LED. It is mainly attributed to three major consequences: (i) reduced grain size of the emissive layer, which facilitates charge recombination, (ii) reduced current leakage due to the enhanced electron-blocking effect, and (iii) improved color purity and air stability owing to better defect passivation. As a result, the optimized composite emissive film can retain the luminescence properties even on exposure to ambient conditions for 80 days and ∼62% of its initial PL intensity can be preserved after 30 days of storage without any encapsulation.

Facile Fabrication of Stretchable Touch-Responsive Perovskite Light-Emitting Diodes Using Robust Stretchable Composite Electrodes.

Perovskite light-emitting diode (PeLED) has been vigorously developed in recent years. As it has demonstrated good performance on the rigid substrates, the next important direction of PeLED is its integration with stretchable components to realize stretchable, responsive device. Here, we describe a facile fabrication of stretchable perovskite light-emissive touch-responsive devices (PeLETDs) by utilizing highly transparent and conductive polyurethane/silver nanowires (PU/AgNWs) as the electrode. Meanwhile, a stretchable tricomposite perovskite emissive layer was developed by blending a small amount of poly(ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP) with CsPbBr3. Additionally, a thin PVP layer was introduced at the bottom of the emissive layer. On one hand, it can further improve the morphology of the emissive layer; on the other hand, it can serve as an electron-injection barrier to reduce the high nonradiative recombination at the corresponding interface. Further, to fulfill the responsive function of the fabricated PeLEDs, a poly(ethylene terephthalate) (PET) spacer with a 100 µm thickness was inserted between the top electrode and the emissive layer. A stretchable PeLETD is finally demonstrated to possess a low turn-on voltage of 2 V with a brightness of 380.5 cd m-2 at 7.5 V and can sustain 30% uniaxial strain with a small luminance variation of 24%. More interestingly, our stretchable PeLETD exhibited high stability, which could be well touch responsivity, where the luminance is on/off switched for 300 cycles by repeatedly applying pressure.

Conjugated Copolymers through Electrospinning Synthetic Strategies and Their Versatile Applications in Sensing Environmental Toxicants, pH, Temperature, and Humidity.

Conjugated copolymers (CCPs) are a class of polymers with excellent optical luminescent and electrical conducting properties because of their extensive π conjugation. CCPs have several advantages such as facile synthesis, structural tailorability, processability, and ease of device fabrication by compatible solvents. Electrospinning (ES) is a versatile technique that produces continuous high throughput nanofibers or microfibers and its appropriate synchronization with CCPs can aid in harvesting an ideal sensory nanofiber. The ES-based nanofibrous membrane enables sensors to accomplish ultrahigh sensitivity and response time with the aid of a greater surface-to-volume ratio. This review covers the crucial aspects of designing highly responsive optical sensors that includes synthetic strategies, sensor fabrication, mechanistic aspects, sensing modes, and recent sensing trends in monitoring environmental toxicants, pH, temperature, and humidity. In particular, considerable attention is being paid on classifying the ES-based optical sensor fabrication to overcome remaining challenges such as sensitivity, selectivity, dye leaching, instability, and reversibility.

A mechanically robust silver nanowire-polydimethylsiloxane electrode based on facile transfer printing techniques for wearable displays.

Silver nanowire (AgNW) networks have attracted considerable attention as transparent electrodes for emerging flexible optoelectronics. However, the transference of such networks onto diverse arbitrary substrates with high conductivity remains a challenge because of the possibility of detaching and sliding occurring at the interface. Therefore, we developed a water-assisted transfer printing method for the fabrication and transfer of an AgNW-polydimethylsiloxane (PDMS) electrode. This innovative approach exhibits a robust ability for thin film transfer onto arbitrary substrates and has highly controlled and nondestructive characteristics. The obtained electrodes exhibited a high ratio of DC conductivity to optical conductivity of 200, a low sheet resistance of 9 Ω sq-1 at 82%, tensile strain (0% to 50%), and flexibility (bending radius of less than 2 mm) without significant loss of conductivity compared with devices fabricated through conventional methods. Furthermore, we demonstrated a novel textile-based flexible light-emitting electrochemical cell (PLEC) based on the stretchable AgNW-PDMS electrode and buckling concept, thereby realizing highly stretchable PLECs with excellent performance and mechanical robustness. The luminance intensity of the strained device was optimized to 58 cd m-2 at 7 V under 10% linear strain without damaging the electroluminescence properties. Notably, this effective and practical transfer method provides a way to develop electronic nanowire devices with unique configurations and high performances.

Novel stretchable thermochromic transparent heaters designed for smart window defroster applications by spray coating silver nanowire.

A productive and novel method for fabricating stretchable transparent heaters with recognised thermochromic properties using commercially available thermochromic ink (TM-55-blue) and silver nanowire (AgNW)-coated polydimethylsiloxane (PDMS) is proposed. Lower resistance, elevated heat generation, and higher transparencies were the expected essential prerequisites for the fabrication of items such as smart windows and window defrosters. AgNW-coated PDMS (hereafter PH devices) satisfied the essential prerequisites but did not produce sufficient color change. In addition to the appreciable electrical and optical characteristics and mechanical robustness, observable color changes represent a critical factor in effortless temperature monitoring by the heating device. Blending TM-55-blue thermochromic ink with PDMS (PBH device) improves the heating rate and color transformation and promotes the ultralow response time appreciably. More notably, it produces a visible transformation from blue to colorless. Color changes visible to the naked eye, ultralow response time, and heating rate represent valuable features for deploying the PBH devices as window defrosters and in smart window applications.

Novel Multifunctional Luminescent Electrospun Fluorescent Nanofiber Chemosensor-Filters and Their Versatile Sensing of pH, Temperature, and Metal Ions.

Novel multifunctional fluorescent chemosensors composed of electrospun (ES) nanofibers with high sensitivity toward pH, mercury ions (Hg2+), and temperature were prepared from poly(N-Isopropylacrylamide-co-N-methylolacrylamide-co-rhodamine derivative) (poly(NIPAAm-co-NMA-co-RhBN2AM)) by employing an electrospinning process. NIPAAm and NMA moieties provide hydrophilic and thermo-responsive properties (absorption of Hg2+ in aqueous solutions), and chemical cross-linking sites (stabilization of the fibrous structure in aqueous solutions), respectively. The fluorescent probe, RhBN2AM is highly sensitive toward pH and Hg2+. The synthesis of poly(NIPAAm-co-NMA-co-RhBN2AM) with different compositions was carried on via free-radical polymerization. ES nanofibers prepared from sensory copolymers with a 71.1:28.4:0.5 NIPAAm:NMA:RhBN2AM ratio (P3 ES nanofibers) exhibited significant color change from non-fluorescent to red fluorescence while sensing pH (the λPL, max exhibited a 4.8-fold enhancement) or Hg2+ (at a constant Hg2+ concentration (10-3 M), the λPL, max of P3-fibers exhibited 4.7-fold enhancement), and high reversibility of on/off switchable fluorescence emission at least five times when Hg2+ and ethylenediaminetetraacetic acid (EDTA) were sequentially added. The P3 ES nanofibrous membranes had a higher surface-to-volume ratio to enhance their performance than did the corresponding thin films. In addition, the fluorescence emission of P3 ES nanofibrous membranes exhibited second enhancement above the lower critical solution temperature. Thus, the ES nanofibrous membranes prepared from P3 with on/off switchable capacity and thermo-responsive characteristics can be used as a multifunctional sensory device for specific heavy transition metal (HTM) in aqueous solutions.

RGB-Switchable Porous Electrospun Nanofiber Chemoprobe-Filter Prepared from Multifunctional Copolymers for Versatile Sensing of pH and Heavy Metals.

Novel red-green-blue (RGB) switchable probes based on fluorescent porous electrospun (ES) nanofibers exhibiting high sensitivity to pH and mercury ions (Hg2+) were prepared with one type of copolymer (poly(methyl methacrylatete-co-1,8-naphthalimide derivatives-co-rhodamine derivative); poly(MMA-co-BNPTU-co-RhBAM)) by using a single-capillary spinneret. The MMA, BNPTU, and RhBAM moieties were designed to (i) permit formation of porous fibers, (ii) fluoresce for Hg2+ detection, and (iii) fluoresce for pH, respectively. The fluorescence emission of BNPTU (fluorescence resonance energy transfer (FRET) donor) changed from green to blue as it detected Hg2+. The fluorescence emission of RhBAM (FRET acceptor) was highly selective for pH, changing from nonfluorescent (pH 7) to exhibiting strong red fluorescence (pH 2). The full-color emission of the ES nanofibers included green, red, blue, purple, and white depending on the particular pH and Hg2+-concentration combination of the solution. The porous ES nanofibers with 30 nm pores were fabricated using hydrophobic MMA, low-boiling-point solvent, and at a high relative humidity (80%). These porous ES nanofibers had a higher surface-to-volume ratio than did the corresponding thin films, which enhanced their performance. The present study demonstrated that the FRET-based full-color-fluorescence porous nanofibrous membranes, which exhibit on-off switching and can be used as naked eye probes, have potential for application in water purification sensing filters.

Novel Magnet and Thermoresponsive Chemosensory Electrospinning Fluorescent Nanofibers and Their Sensing Capability for Metal Ions.

Novel multifunctional switchable chemosensors based on fluorescent electrospun (ES) nanofibers with sensitivity toward magnetism, temperature, and mercury ions (Hg2+) were prepared using blends of poly(N-isopropylacrylamide)-co-(N-methylolacrylamide)-co-(Acrylic acid), the fluorescent probe 1-benzoyl-3-[2-(2-allyl-1,3-dioxo-2,3-dihydro-1Hbenzo[de]isoquinolin-6-ylamino)-ethyl]-thiourea (BNPTU), and magnetite nanoparticles (NPs), and a single-capillary spinneret. The moieties of N-isopropylacrylamide, N-methylolacrylamide, acrylic acid, BNPTU, and Iron oxide (Fe3O4) NPs were designed to provide thermoresponsiveness, chemical cross-linking, Fe3O4 NPs dispersion, Hg2+ sensing, and magnetism, respectively. The prepared nanofibers exhibited ultrasensitivity to Hg2+ (as low as 10-3 M) because of an 80-nm blueshift of the emission maximum (from green to blue) and 1.6-fold enhancement of the emission intensity, as well as substantial volume (or hydrophilic to hydrophobic) changes between 30 and 60 °C, attributed to the low critical solution temperature of the thermoresponsive N-isopropylacrylamide moiety. Such temperature-dependent variations in the presence of Hg2+ engendered distinct on⁻off switching of photoluminescence. The magnetic ES nanofibers can be collected using a magnet rather than being extracted through alternative methods. The results indicate that the prepared multifunctional fluorescent ES nanofibrous membranes can be used as naked eye sensors and have the potential for application in multifunctional environmental sensing devices for detecting metal ions, temperature, and magnetism as well as for water purification sensing filters.

Novel highly selective and reversible chemosensors based on dual-ratiometric fluorescent electrospun nanofibers with pH- and Fe(3+)-modulated multicolor fluorescence emission.

Novel dual-ratiometric fluorescent electrospun (ES) nanofibers featuring high sensitivity for pH and ferric ion (Fe(3+)) were prepared using binary blends of poly(2-hydroxyethyl methacrylate-co-N-methylolacrylamide-co-nitrobenzoxadiazolyl derivative) (poly(HEMA-co-NMA-co-NBD)) and a spirolactam rhodamine derivative (SRhBOH) by employing a single-capillary spinneret. The HEMA, NMA, and NBD moieties were designed to exhibit hydrophilic properties, chemical cross-linking, and fluorescence (fluorescence resonance energy transfer (FRET) donor), respectively. The fluorescence emission of SRhBOH was highly selective for pH and Fe(3+); when SRhBOH detected acidic media and Fe(3+), the spirocyclic form of SRhBOH, which is nonfluorescent, was transformed into the opened cyclic form and exhibited strong fluorescence emission. The emission colors of ES nanofibers in acidic or Fe(3+) aqueous solutions changed from green to red because of FRET from NBD (donor) to SRhBOH (acceptor). The off/on switching of the FRET process was modulated by adjusting the SRhBOH blending ratio, pH, and Fe(3+) concentration. Poly(HEMA-co-NMA-co-NBD) ES fibers blended with 20% SRhBOH showed high sensitivity in sensing Fe(3+) and pH because of the substantial 57 nm red shift in emission as well as substantial reversible dual photoluminescence. The prepared FRET-based dual-ratiometric fluorescent ES nanofibrous membranes can be used as "naked eye" sensors and have potential for application in multifunctional environment sensing devices.