Highly Stretchable Sound?in?Display Electronics Based on Strain?Insensitive Metallic Nanonetworks
ABSTRACT: Abstract The growing importance of human–machine interfaces and the rapid expansion of the internet of things (IoT) have inspired the integration of displays with sound generation systems to afford stretchable sound?in?display devices and thus establish human?to?machine connections via auditory system visualization. Herein, the synchronized generation of sound and color is demonstrated for a stretchable sound?in?display device with electrodes of strain?insensitive silver nanowires (AgNWs) and emissive layers of field?induced inorganic electroluminescent (EL) phosphors. In this device, EL phosphors embedded in a dielectric elastomer actuator (DEA) emit light under alternating?current bias, while audible sound waves are simultaneously generated via DEA actuation along with input sound signals. The electroluminescence and sound?generation performances of the fabricated device are highly robust and reliable, being insensitive to stretch?release cycling because of the presence of the AgNW stretchable electrodes. The presented principle of integrating light emission and acoustic systems in a single stretchable device can be further expanded to realize sound?in?display electronics for IoT and human–machine interface applications. A stretchable sound?in?display with electrodes of strain?insensitive silver nanowires and emissive layers of field?induced inorganic electroluminescent (EL) phosphors are proposed for generation of synchronized acoustic and visual information. The loudspeaker simultaneously emits light by the EL and generates sound by the vibration of the dielectric elastomer actuator under the same bias, allowing the synesthetic perception of both color and sound.
Project description:We demonstrate wide colour tunability of polydimethylsiloxane-based alternating-current-driven electroluminescent devices with intrinsically stretchable characteristics achieved by simply modulating the electrical frequency. By employing both a screen-printed emitting layer and frequency-dependent colour tuning of ZnS:Cu-based phosphors, we demonstrate various coloured patterned images in a single device. We also show enhanced colour-tuning performance by mixing multi-colour phosphors, which results in a broad range of available coordinates in colour space. We believe that our demonstrated method could be used for manipulating broader colour expression as well as in various applications involving stretchable devices.
Project description:We demonstrated the tri-functional device based on all powder-processing methods by using ZnS powder as phosphor layer and piezoelectric material as dielectric layer. The fabricated device generated the electroluminescent (EL) light from phosphor and the sound from piezoelectric sheet under a supply of external electric power, and additionally harvested the reverse-piezoelectric energy to be converted into EL light. Under sinusoidal applied voltage, EL luminances were exponentially increased with a maximum luminous efficiency of 1.3?lm/W at 40?V and 1,000?Hz, and sound pressure levels (SPLs) were linearly increased. The EL luminances were linearly dependent on applied frequency while the SPLs showed the parabolic increase behavior below 1,000?Hz and then the flat response. The temperature dependence on EL luminances and SPLs was demonstrated; the former was drastically increased and the latter was slightly decreased with the increase of temperature. Finally, as an energy harvesting application, the piezoelectric-induced electroluminescence effect was demonstrated by applying only mechanical pressure to the device without any external electric power.
Project description:Building transient electronics are promising and emerging strategy to alleviate the pollution issues from electronic waste (e-waste). Although a variety of transient devices comprising organic and inorganic materials have been described, transient light emitting devices are still elusive but highly desirable because of the huge amount of lighting and display related consumer electronics. Here we report a simple and efficient fabrication of large-area flexible transient alternating current electroluminescent (ACEL) device through a full-solution processing method. Using transparent flexible AgNW-polymer as both electrodes, the devices exhibit high flexibility and both ends side light emission, with the features of controlled size and patterned structure. By modulating the mass ratio of blue and yellow phosphors, the emission color is changed from white to blue. Impressively, the fabricated ACEL device can be thoroughly dissolved in water within 30?min. Our strategy combining such advances in transient light emitting devices with simple structure, widely used materials, full solution process, and high solubility will demonstrate great potential in resolving the e-waste from abandoned light-emitting products and expand the opportunities for air-stable flexible light emitting devices.
Project description:Focused MeV ion beams with micrometric resolution are suitable tools for the direct writing of conductive graphitic channels buried in an insulating diamond bulk, as already demonstrated for different device applications. In this work we apply this fabrication method to the electrical excitation of color centers in diamond, demonstrating the potential of electrical stimulation in diamond-based single-photon sources. Differently from optically-stimulated light emission from color centers in diamond, electroluminescence (EL) requires a high current flowing in the diamond subgap states between the electrodes. With this purpose, buried graphitic electrode pairs, 10 μm spaced, were fabricated in the bulk of a single-crystal diamond sample using a 6 MeV C microbeam. The electrical characterization of the structure showed a significant current injection above an effective voltage threshold of 150 V, which enabled the stimulation of a stable EL emission. The EL imaging allowed to identify the electroluminescent regions and the residual vacancy distribution associated with the fabrication technique. Measurements evidenced isolated electroluminescent spots where non-classical light emission in the 560-700 nm spectral range was observed. The spectral and auto-correlation features of the EL emission were investigated to qualify the non-classical properties of the color centers.
Project description:Electroluminescent (EL) devices have been extensively integrated into multi-functionalized electronic systems in the role of the vitally constituent light-emitting part. However, the lifetime and reliability of EL devices are often severely restricted by concomitant damage, especially when the strain exceeds the mechanical withstanding limit. We report a self-healable EL device by adopting a modified self-healable polyacrylic acid hydrogel as the electrode and a self-healable polyurethane as a phosphor host to realize the first omni-layer-healable light-emitting device. The physicochemical properties of each functionalized layer can be efficiently restored after experiencing substantial catastrophic damage. As a result, the luminescent performance of the self-healable EL devices is well recovered with a high healing efficiency (83.2% for 10 healing cycles at unfixed spots, and 57.7% for 20 healing cycles at a fixed spot). In addition, inter-device healing has also been developed to realize a conceptual "LEGO"-like assembly process at the device level for light-emitting devices. The design and realization of the self-healable EL devices may revive their performance and expand their lifetime even after undergoing a deadly cut. Our self-healable EL devices may serve as model systems for electroluminescent applications of the recently developed ionically conductive healable hydrogels and dielectric polymers.
Project description:We present a mechanically active cell culture substrate that produces complex strain patterns and generates extremely high strain rates. The transparent miniaturized cell stretcher is compatible with live cell microscopy and provides a very compact and portable alternative to other systems. A cell monolayer is cultured on a dielectric elastomer actuator (DEA) made of a 30??m thick silicone membrane sandwiched between stretchable electrodes. A potential difference of several kV's is applied across the electrodes to generate electrostatic forces and induce mechanical deformation of the silicone membrane. The DEA cell stretcher we present here applies up to 38% tensile and 12% compressive strain, while allowing real-time live cell imaging. It reaches the set strain in well under 1?ms and generates strain rates as high as 870?s-1, or 87%/ms. With the unique capability to stretch and compress cells, our ultra-fast device can reproduce the rich mechanical environment experienced by cells in normal physiological conditions, as well as in extreme conditions such as blunt force trauma. This new tool will help solving lingering questions in the field of mechanobiology, including the strain-rate dependence of axonal injury and the role of mechanics in actin stress fiber kinetics.
Project description:Stretchable electronics can bridge the gap between hard planar electronic circuits and the curved, soft and elastic objects of nature. This has led to applications like conformal displays, electronic skin and soft neuroprosthetics. A remaining challenge, however, is to match the dimensions of the interfaced systems, as all require feature sizes well below 100 μm. Intrinsically stretchable nanocomposites are attractive in this context as the mechanical deformations occur on the nanoscale, although methods for patterning high performance materials have been lacking. Here we address these issues by reporting on a multilayer additive patterning approach for high resolution fabrication of stretchable electronic devices. The method yields highly conductive 30 μm tracks with similar performance to their macroscopic counterparts. Further, we demonstrate a three layer micropatterned stretchable electroluminescent display with pixel sizes down to 70 μm. These presented findings pave the way towards future developments of high definition displays, electronic skins and dense multielectrode arrays.
Project description:Stretchable materials are essential for next generation wearable and stretchable electronic devices. Intrinsically stretchable and highly conductive polymers (termed ISHCP) are designed with semi interpenetrating polymer networks (semi-IPN) that enable polymers to be simultaneously applied to transparent electrodes and electrochromic materials. Through a facile method of acid-catalyzed polymer condensation reaction, optimized ISHCP films show the highest electrical conductivity, 1406 S/cm, at a 20% stretched state. Without the blending of any other elastomeric matrix, ISHCP maintains its initial electrical properties under a cyclic stretch-release of over 50% strain. A fully stretchable electrochromic device based on ISHCP is fabricated and shows a performance of 47.7% ?T and high coloration efficiency of 434.1 cm<sup>2</sup>/C at 590 nm. The device remains at 45.2% ?T after 50% strain stretching. A simple patterned electrolyte layer on a stretchable electrochromic device is also realized. The fabricated device, consisting of all-plastic, can be applied by a solution process for large scale production. The ISHCP reveals its potential application in stretchable electrochromic devices and satisfies the requirements for next-generation stretchable electronics.
Project description:In this study, we revealed a new approach for the development of new triplet-triplet annihilation (TTA) materials with highly efficient deep-blue fluorescence via the incorporation of a styrylpyrene core and an electron-donating group. The resulting deep-blue emitters (PCzSP, DFASP, and DPASP) exhibit intramolecular charge transfer emissions with remarkably high emission quantum yields. The electroluminescent devices based on these three fluorophores as dopants using CBP as a host exhibit very high device efficiencies; in particular, the DPASP-doped device reveals an extremely high EQE of 12%, reaching the limit of a TTA-based device. The EL characteristics of DPASP-doped CBP-based devices at various doping concentrations (0-5%) suggest that the dopant DPASP is responsible for the TTA-type delayed fluorescence in the device; no delayed fluorescence was observed for the device using CBP as the host emitter. Moreover, when using DMPPP with ambipolar characteristics as the host, the deep-blue DPASP-doped device also gives outstanding performance with an EQE of nearly 11% with an extremely small efficiency roll-off, which was ascribed to the excellent charge balance in the emitting layer of the EL device. The TTA process of the SP-based dopants accounts significantly for the superior efficiencies of the EL devices.
Project description:There is a growing interest in fibers supporting optoelectrical properties for textile and wearable display applications. Solution-processed electroluminescent (EL) material systems can be continuously deposited onto fiber or yarn substrates in a roll-to-roll process, making it easy to scale manufacturing. It is important to have precise control over layer deposition to achieve uniform and reliable light emission from these EL fibers. Slot-die coating offers this control and increases the rate of EL fiber production. Here, we report a highly adaptable, cost-effective 3D printing model for developing slot dies used in automatic coating systems. The resulting slot-die coating system enables rapid, reliable production of alternating current powder-based EL (ACPEL) fibers and can be adapted for many material systems. The benefits of this system over dip-coating for roll-to-roll production of EL fibers are demonstrated in this work.