Alice Lee-Sie Eh

Extremely Stretchable Electroluminescent Devices with Ionic Conductors

An extremely stretchable electroluminescent device is fabricated based on alternating-current electroluminescent (ACEL) materials and ionic conductors. The stretchable ACEL device possesses extremely high stretchability, and can be linearly stretched to 700% with the luminance being maintained at 70% of the initial value before stretching. The ACEL device can be repetitively stretched to 400% with stable emission behavior.

Spray coated ultrathin films from aqueous tungsten molybdenum oxide nanoparticle ink for high contrast electrochromic applications

Ultrathin tungsten molybdenum oxide nanoparticle films were fabricated from aqueous ink by a spray coating technique. With the in situ heating of the hot plate during the spray coating process, the detrimental effects of oxygen vacancies on electrochromic (EC) materials could be eliminated. The spray coated ultrathin films exhibit higher contrast than the drop casted films, which would provide a versatile and promising platform for energy-saving smart (ESS) windows, batteries, and other applications.

A copper-based reversible electrochemical mirror device with switchability between transparent, blue, and mirror states

Herein, a reversible electrochemical mirror (REM) device was electrochemically tuned to achieve dual transmittance and reflectance modulations in a single device. Conventional REM devices reversibly switch between transparent and mirror states. However, it is a significant challenge to maintain the mirror state of the REM devices due to the diffusion of anions into the metal film at the open-circuit state. In this study, we report a Cu-based REM device that offers reversible switching between transparent, blue, and mirror states via a judicious selection of electrolyte and controllable electrodeposition. The blue state can be obtained through the formation of copper(I) chloride (CuCl) when copper(II) chloride (CuCl2) undergoes electrochemical reduction. Moreover, the polymer host PVA (polyvinyl alcohol) plays an important role in reducing the surface roughness of the electrodeposited mirror film, improving film uniformity, and maintaining the mirror state of the device during the voltage-off state.

Inkjet-printed metal oxide nanoparticles on elastomer for strain-adaptive transmissive electrochromic energy storage systems

ABSTRACT The emergence of soft energy devices provides new possibilities for various applications, it also creates significant challenges in the selection of structural design and material compatibility. Herein, we demonstrate a stretchable transmissive electrochromic energy storage device by inkjet-printing single layer of WO3 nanoparticles on an elastomeric transparent conductor. Such hybrid electrode is highly conductive and deformable, making it an excellent candidate for the application: large optical modulation of 40%, fast switching speed (<4.5 s), high coloration efficiency (75.5 cm2 C−1), good stability and high specific capacity (32.3 mAh g−1 and 44.8 mAh cm−3). The device consists of WO3-based hybrid electrode and polyaniline/carbon nanotubes composite electrode. It maintains excellent electrochromic and energy storage performance even when stretched up to 50%, and achieves a maximum areal energy density of 0.61 μWh cm−2 and power density of 0.83 mW cm−2, which is one of the highest values in stretchable transparent energy storage devices. A device featuring stretchable transparent nanowires based electrode is illustrated as an energy indicator in which the stored energy can be monitored via reversible color variation. This high performance and multifunctional electrochromic energy storage device is a promising candidate for deformable and wearable electronics. Graphical Abstract

Diphylleia grayi-Inspired Stretchable Hydrochromics with Large Optical Modulation in the Visible–Near-Infrared Region

Some animals and plants in nature are endowed with elegant color-changing ability, which inspired the development of biomimetic systems with multifunctionality, such as controllable colors, transmittance, and mechanical pliability that are significant for the development of energy-efficient and deformable chromic devices, such as wearable displays, smart windows, decorative architectures, camouflage devices, etc. Inspired by the color-changing ability of Diphylleia grayi (commonly known as the skeleton flower), we developed a porous poly(dimethylsiloxane) (PDMS) film that dynamically and dramatically changes its color by the adsorption/desorption of a minute amount of water (5 g m-2) or other solvents. This hydrochromic phenomenon was analyzed in detail, and it matched well with the Mie scattering theory. The porous PDMS film of about 0.4 mm thickness exhibits a large optical modulation (about 75-80%) in the broad visible and near-infrared region and a coloration speed of less than 9 min. Additionally, the PDMS film can sustain uniaxial strain up to 100% in both transparent and colored states. We believe this new strategy to develop highly scalable porous PDMS films offers a practical route to realize bionic and botanic inspired deformable energy-efficient façades, chromogenic wearables, smart windows, smart displays, camouflage devices, etc.

Electroluminescent Devices: Extremely Stretchable Electroluminescent Devices with Ionic Conductors (Adv. Mater. 22/2016)

An extremely stretchable electroluminescent device is fabricated by P. S. Lee and co-workers, as described on page 4490. The stretchable alternating-current electroluminescent (ACEL) device possesses extremely high stretchability, and can be linearly stretched to 700% with the luminance being maintained at 70% of the initial value before stretching. The device can be repeatedly stretched to 400% with stable emission behavior. The presented device will provide new opportunities in stretchable lighting, volumetric 3D displays, interactive readout systems, and other unprecedented applications.