Do Van Lam

Calligraphic ink enabling washable conductive textile electrodes for supercapacitors

The appeal of wearable devices for future electronics has stimulated scientists to unearth novel materials to meet the technological demands of modern society. However, the washability issue still remains a significant challenge. We showed that calligraphic ink, used as a writing tool in East Asian areas for thousands of years, could present a route to translate washable and wearable electrodes into a reality. We prepared washable electrodes by simply coating textiles with the ink. It was observed that the electrical and mechanical performance of the fabricated electrodes remained nearly unchanged even after 10 vigorous laundering cycles using a regular washing machine. In addition, supercapacitors made with those electrodes exhibited excellent cycling stability and high energy/power density. These results establish that everyday calligraphic ink is a simple yet powerful resource for fashioning normal textiles into washable and wearable electrodes for supercapacitors.

Graphene-based stretchable and transparent moisture barrier

We propose an alumina-deposited double-layer graphene (2LG) as a transparent, scalable, and stretchable barrier against moisture; this barrier is indispensable for foldable or stretchable organic displays and electronics. Both the barrier property and stretchability were significantly enhanced through the introduction of 2LG between alumina and a polymeric substrate. 2LG with negligible polymeric residues was coated on the polymeric substrate via a scalable dry transfer method in a roll-to-roll manner; an alumina layer was deposited on the graphene via atomic layer deposition. The effect of the graphene layer on crack generation in the alumina layer was systematically studied under external strain using an in situ micro-tensile tester, and correlations between the deformation-induced defects and water vapor transmission rate were quantitatively analyzed. The enhanced stretchability of alumina-deposited 2LG originated from the interlayer sliding between the graphene layers, which resulted in the crack density of the alumina layer being reduced under external strain.

Morphology and Structure Anlysis of Graphene by Low Voltage TEM

Graphene, a single atomic monolayer of sp 2 -bonded hexagonal carbon with extraordinary mechanical, electronic, and optical properties, has become a subject of great interest in materials science. Since its first isolation in 2004, graphene has been researched by many research groups in the fields of physics, chemistry and material. And it is expected that graphene will be applied in various industry [1]. To analyze properties of graphene, optical and electrical analyses are well used [2, 3]. For observation of graphene morphology, electron microscopy, atomic force microscopy and scanning tunneling microscopy, etc. have been used. But it is very difficult to observe graphene because of its ultra-thin thickness.