Akira Magario

High-Brightness Electron Emission from Flexible Carbon Nanotube/Elastomer Nanocomposite Sheets

Carbon nanotube (CNT)/elastomer nanocomposites (CECs) are flexible and easy to fabricate accordng to the required size and form. We succeeded in realizing a uniform dispersion of CNTs in the elastomer matrices of natural rubber (NR). Intense electron emission from the CEC sheets has been confirmed; the threshold electric field is about 1 V/µm, and the saturation current density reaches 10 mA/cm2. We discuss composite structures consisting of electrically conductive CNT networks dispersed in the insulating NR matrix. Local electric field is enhanced at the CEC surface, and the low threshold field is attributed to the sharp tips and side walls of bent CNTs that appeared on the surface.

Carbon Nanotube/Aluminum Composites As a Novel Field Electron Emitter

We have succeeded in homogeneously dispersing multi-walled carbon nanotubes (MWNTs) into an aluminum (Al) matrix by a novel elastomer precursor method. In thus prepared composite, the disentangled MWNTs were tightly bound to the Al matrix via oxygen-mediated AlN interfacial layer. The morphology of the composite surface was controlled by different polishing procedures and their field electron emission characteristics were investigated using a mesh-gate triode-type device. The MWNT/Al plate with well-rugged surface emitted electrons over a threshold electric field of 3 V/µm. The current density of 1 mA/cm2 was obtained at 6 V/µm and the luminance reached 400 cd/m2 under operation at 8 V/µm.

Side electron emission device using carbon nanofiber/elastomer composite sheet

A side electron emission device was made of a carbon nanofiber/elastomer composite sheet. Instead of a conventional field emission configuration, electron emitters consisting of cross-sectional sides of the composite sheet were put in position perpendicular to the phosphor/anode surface by inserting an insulating spacer. Light emission of 4200cd∕m2 at 1kV was achieved by intense electron emission from the cross section since the carbon nanofibers preferentially orient parallel to the sheet plane and stick out of the cross section. This simple device structure enabled us to fabricate a flexible, transparent field emission device.

Flexible Field Emission Device Using Carbon Nanofiber Nanocomposite Sheet

We have investigated detailed field emission characteristics of side electron emission from carbon nanofiber (CNF)/elastomer nanocomposite sheet. Strong electron emission from the cross-sectional cutting side of the CNF/elastomer nanocomposite sheet has been confirmed even for cured nanocomposites. The threshold voltage is less than 200 V and the saturation current has been found to increase gradually with the applied voltage. Utilizing the side electron emission configuration, highly efficient, indium–tin-oxide free, flexible field emission device has been demonstrated.

Field-emission properties of carbon nanotube composite in side-electron emission configuration

Field-emission characteristics of a carbon nanotube (CNT)/elastomer composite have been investigated. We performed theoretical calculations of the field distribution in a field emission device structure with the side-electron configuration of the composite sheet. According to the calculation results, the electric field is found to be concentrated at the edge of the composite sheet which leads to an enhancement of the local electric field at the CNT tips protruding from the composite. Furthermore, we calculated the trajectories of emitted electrons. From the obtained results, bright luminescence over 37000 cd/m2 from green phosphor was obtained by optimizing the electrode structure.

Field Electron Emission Devices with Oriented Carbon Nanotubes Dispersed in Aluminum Composites

Multiwalled carbon nanotubes (MWNTs) were homogeneously dispersed into aluminum (Al) powder by the elastomer precursor method. MWNT/Al composites were prepared by extrusion molding of the precursor powder and cut into thin plates. Each composite plate was split parallel or perpendicular to the extrusion direction, and used for field emission measurements. The perpendicular cross section exhibited excellent electron emission with a threshold electric field of 2.0 V/µm and a current density of 1.5 mA/cm2 since a considerable number of oriented MWNTs were sticking out of the cross-sectional surface. With those oriented MWNT/Al composite emitters, a flat-panel field emission lamp (FEL) was successfully fabricated by using the side-electron emission device (SEED) structure.