Higher Light Density through Use of CNT
Investigations at Wake Forest University in North Carolina have shown that the light density of electroluminescent polymers can be increased significantly through use of carbon nanotubes (CNT). For this purpose, multiwall carbon nanotubes (MWNT) were incorporated into the emitter layer of luminous elements. The MWNT increased the light density of the system by a factor of five. The highest light density was achieved with a MWNT content of about 0.04 wt. %.
CNT consist of one or more graphite layers that have formed tubes. Because of their structure, they exhibit extremely high electrical conductivity. Apparently, the MWNT function as channels in the luminous elements, facilitating electron transport and the formation of charge carriers.
According to the report from Wake Forest University, the light generated in this way is very similar to natural sunlight. The energy efficiency of these "field-induced electroluminescent polymers (FIPEL)" is reportedly twice as high as that of commercially available energy-saving bulbs. This is almost the energy efficiency of LEDs. The researchers believe that production of FIPEL light sources, however, could be less expensive, since they do not contain any electronic components.
FIPEL light sources can be designed to have any shape: they can be large flat plates and also formed into lightbulbs. The light sources contain no toxic substances and are shatterproof. In addition, there is no humming sound during operation as there is with fluorescent tubes. In addition to illumination of living areas and offices, the researchers see additional potential applications in public transportation. By working together with the CeeLite company, they hope to bring these new light sources onto the market in the next few years.