Infrared Nanotube Films Offer Advantages for Solar Cells and More

March 11, 2009 By Lisa Zyga feature
Researchers have found that nanotube films have very good infrared transmission that could improve the efficiency of infrared solar cells. Image credit: Royal Society of Chemistry.

( -- Researchers have already known that carbon nanotube thin films have mechanical and conductive advantages that could make them useful as electrodes in solar cells, solid state lighting, and electronic displays. However, studies so far have focused on how well nanotube films transmit light in the visible range, but have not explored the films’ infrared properties.

In a recent study, physicists Liangbing Hu, David Hecht, and George Grüner from the University of California, Los Angeles, have investigated the of single-walled that are optically transparent and electrically conductive. They found that the nanotube films have an outstanding ability for transmitting infrared waves. In experiments, nanotube electrodes and electrodes outperformed various other materials in several key categories, opening up a variety of infrared applications for the nanotube films.

“This is the first time that the infrared properties of conductive CNT films are fully studied through measurement and calculations,” Hu told

To fabricate the nanotube films, the scientists dispersed nanotubes in water with the help of a surfactant, and then sprayed the substance onto heated substrates to create films. When shining an on the nanotube films, the scientists found that the films maintained an average transmittance rate of more than 90% over a wide (450 nanometers - 20 micrometers).

Because of the nanotube films’ high infrared transmittance, the scientists explain that they would make poor candidates for blocking heat, but would be useful for applications that require heat dissipation. One prominent example is . Since a large portion of solar energy is above a wavelength of 1 micrometer (longer than optical wavelengths), transparent nanotube thin films could be used to capture excess heat in infrared solar cells, making the solar cells more efficient.

“One major application is the infrared solar cells, where transparent CNT films as well graphene films would allow the transmission of infrared energy to the active layer, which allows the fabrication of infrared solar cells,” Hu said.

Compared with other materials known to transmit infrared waves, the nanotube films have the lowest reflection rate (less than 10%) of those addressed in the study. This advantage means that nanotube films might not require an antireflective coating like the others. In addition, nanotube films have high cutoff wavelengths (they transmit longer infrared wavelengths) compared with the other materials. This property could make the films especially useful for applications in the far infrared range.

The films could also serve as electrodes for a variety of industrial and military applications, such as infrared imaging, sensing, and emission, as well as modulators for fiber communications. Hu added that, in the future, the researchers plan to investigate using the films for an infrared camera.

More information: Hu, Liangbing; Hecht, David S.; Grüner, George. “Infrared transparent carbon nanotube thin films.” Applied Physics Letters 94, 081103 (2009).

Copyright 2009
All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of

Explore further: Transparent and Conductive Nanotube Films for Consumer and Military Applications

Related Stories

Will carbon nanotubes replace indium tin oxide?

March 9, 2009

( -- Up until now, George Grüner tells, most of the studies regarding the properties - and uses - of carbon nanotubes have been restricted to the visible spectral range. “We, however, were interested ...

Nanotubes find niche in electric switches

March 10, 2009

New research from Rice University and the University of Oulu in Oulu, Finland, finds that carbon nanotubes could significantly improve the performance of electrical commutators that are common in electric motors and generators.

Recommended for you

For 2-D boron, it's all about that base

September 2, 2015

Rice University scientists have theoretically determined that the properties of atom-thick sheets of boron depend on where those atoms land.

An engineered surface unsticks sticky water droplets

August 31, 2015

The leaves of the lotus flower, and other natural surfaces that repel water and dirt, have been the model for many types of engineered liquid-repelling surfaces. As slippery as these surfaces are, however, tiny water droplets ...

Electrical circuit made of gel can repair itself

August 25, 2015

(—Scientists have fabricated a flexible electrical circuit that, when cut into two pieces, can repair itself and fully restore its original conductivity. The circuit is made of a new gel that possesses a combination ...

Scientists grow high-quality graphene from tea tree extract

August 21, 2015

(—Graphene has been grown from materials as diverse as plastic, cockroaches, Girl Scout cookies, and dog feces, and can theoretically be grown from any carbon source. However, scientists are still looking for a ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.