Optoelectronics with Carbon Nanotubes

tube has been subjected to much less chemical processing, and it does not rely on percolation for
conduction. But we can never achieve significant total light output with the single device
because we cannot pass more than about 1 μA of current without destroying the tube itself.
Ideally, parallel single-tube devices with good quality, long small-diameter CNTs that are almost
exclusively semiconducting would be ideal for the maximum light output, but there is much
technical challenge before such a device can be constructed. Our parallel-tube, percolation-
driven devices are the best CNT electrical emitter to date in terms of total light intensity.
(a) (b) (c)
(d)
Figure V-6. Spatial characteristics of EL from a 4-μm CNT light emitting diode
taken at the same sample position. Note that the device dimensions are close to the
resolution limit (~1 μm) of the optical measurement due to both the wavelength of the
detected light and the pixel size. (a) Reflected image of a device showing the source
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