Mengqi Cui

Highly Stretchable Piezoresistive Graphene–Nanocellulose Nanopaper for Strain Sensors

Highly stretchable graphene-nanocellulose composite nanopaper is fabricated for strain-sensor applications. Three-dimensional macroporous nanopaper from crumpled graphene and nanocellulose is embedded in elastomer matrix to achieve stretchability up to 100%. The stretchable graphene nanopaper is demonstrated for efficient human-motion detection applications.

Stretchable and Wearable Electrochromic Devices

Stretchable and wearable WO3 electrochromic devices on silver nanowire (AgNW) elastic conductors are reported. The stretchable devices are mechanically robust and can be stretched, twisted, folded, and crumpled without performance failure. Fast coloration (1 s) and bleaching (4 s) time and good cyclic stability (81% retention after 100 cycles) were achieved at relaxed state. Proper functioning at stretched state (50% strain) was also demonstrated. The electrochromic devices were successfully implanted onto textile substrates for potential wearable applications. As most existing electrochromic devices are based on rigid technologies, the innovative devices in their soft form hold the promise for next-generation electronics such as stretchable, wearable, and implantable display applications.

An Intrinsically Stretchable Nanowire Photodetector with a Fully Embedded Structure

Fabrication of intrinsically stretchable nanowire photodetectors based on fully embedded structures is reported. A lithographic filtration method is used to integrate different functional layers into the photodetectors, which exhibit excellent stretchability up to 100%. The fully embedded structure enables excellent stability against repeated stretching, mechanical scratching, and adhesive forces.

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 High-Performance Lithium-Ion Capacitor Based on 2D Nanosheet Materials

Lithium-ion capacitors (LICs) are promising electrical energy storage systems for mid-to-large-scale applications due to the high energy and large power output without sacrificing long cycle stability. However, due to the different energy storage mechanisms between anode and cathode, the energy densities of LICs often degrade noticeably at high power density, because of the sluggish kinetics limitation at the battery-type anode side. Herein, a high-performance LIC by well-defined ZnMn2 O4 -graphene hybrid nanosheets anode and N-doped carbon nanosheets cathode is presented. The 2D nanomaterials offer high specific surface areas in favor of a fast ion transport and storage with shortened ion diffusion length, enabling fast charge and discharge. The fabricated LIC delivers a high specific energy of 202.8 Wh kg-1 at specific power of 180 W kg-1 , and the specific energy remains 98 Wh kg-1 even when the specific power achieves as high as 21 kW kg-1 .

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.

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.