A transparent and stretchable graphene-based actuator for tactile display.

A tactile display is an important tool to help humans interact with machines by using touch. In this paper, we present a transparent and stretchable graphene-based actuator for advanced tactile displays. The proposed actuator is composed of transparent and compliant graphene electrodes and a dielectric elastomer substrate. Since the electrode is coated onto the appointed region of the substrate layer by layer, only the area of the dielectric elastomer substrate with electrodes bumps up in response to the input voltage, which consequently produces actuation. The actuator is proven to be operable while preserving its electrical and mechanical properties even under 25% stretching. Also, the simple fabrication of the proposed actuator is cost-effective and can easily be extended to multiple arrays. The actuator is expected to be applicable to various applications including tactile displays, vari-focal lenses etc.

Efficient inverted bulk heterojunction photovoltaic devices using a transparent polymeric interfacial buffer layer with C60 pendant and UV curable groups.

We demonstrate the synthesis of a transparent, polymeric n-type material (M1) consisting of C60 pendant and UV curable groups in side chains. This material (M1) is employed as a polymeric n-type interfacial buffer layer for an efficient inverted bulk heterojunction (BHJ) photovoltaic device based on regioregular poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PC61BM) active layer. Under simulated solar illumination of AM 1.5G (100 mW/cm2), the highest efficient devices fabricated with a configuration of ITO/interfacial buffer layer (M1,10 nm)/P3HT:PC61BM (1:0.9 w:w) (120 nm)/PEDOT:PSS (30 nm)/Ag (100 nm) achieve an average power conversion efficiency PCE of 2.16%, with short-circuit current J(SC) = 6.70 mA/cm2, fill factor FF = 54.2%, and open-circuit voltage V(OC) = 0.60 V. This result is comparable to the inverted BHJ photovoltaic devices fabricated with Cs2CO3, one of widely used as a buffer layer. The synthesized M1 have thus proven to be promising polymeric interfacial buffer layer for high efficient BHJ photovoltaic devices.

Carbon-nanotube/silver networks in nitrile butadiene rubber for highly conductive flexible adhesives.

An adhesive with high conductivity, flexibility, cyclability, oxidation resistance, and good adhesion is developed using microscale silver flakes, multiwalled carbon nanotubes decorated with nanoscale silver particles, and nitrile butadiene rubber. Light-emitting-diode chips are attached to the conductive, flexible adhesive pattern on a poly(ethylene terephthalate) substrate as a visual demonstration. The brightness is invariant during bending tests.