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Transparent Conducting CNT Films

Transparent conductors are critical components in many optoelectronic devices such as flat-panel displays (FPDs), touch screens, solar cells, electroluminescent lamps, "smart" windows, and solid state lighting systems. Since the 1960s, indium tin oxide (ITO) has been the material of choice to provide electrical conductivity to optically transparent glass and polymeric films, in a number of industries including aerospace, architectural glass, solar energy, and lighting.

The fastest-growing application for ITO is in FPDs, which are found in a wide variety of applications such as instrument panels for airplanes and automobiles, consumer electronics, video phones, displays for home appliances, televisions, and video games, and displays with specialty requirements for the medical and military markets. These diverse applications have varying display requirements that are met by a combination of device design and optical enhancements. In all of these devices, ITO acts as transparent conducting electrodes addressing each pixel, or larger zone, on the display screen.

However, ITO suffers from some significant limitations. ITO films are brittle, creating mechanical reliability problems for flexible display applications. Deposition processes for ITO films are costly, and may be prohibitively so for large-area applications. Carbon nanotubes (CNTs) are particularly good candidates to replace ITO films for many applications. CNTs can be either electrically conductive or semiconductive, depending on their helicity, leading to nanoscale wires and electrical components. These one-dimensional fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times greater than steel at one sixth the weight, and high strain to failure.

Utilizing YTCA's proprietary technology, thin films comprising networks of carbon nanotubes of varying electrical conductivity and optical transmission can be produced on various substrates. Such transparent conducting CNT coatings may closely match the properties of ITO in conductive transparent applications, are cheaper to produce, and are far more flexible and stable under UV radiation and chemical environments.

Transparent conducting CNT films of varying optical transmission deposited on glass.

© 2008 YTC America Inc.