Home > Press > Researchers show that carbon nanotubes are electrochromic
Carbon nanotube films change color when subject to an applied voltage. (© 2011 Wiley-VCH) |
Abstract:
Smart glass can change color or even go from opaque to transparent with just the flick of a switch. Indium tin oxide is used as an electrical contact in many of these 'electrochromic' devices because it is both transparent to visible light and a good conductor of electricity. But indium and tin are both becoming increasingly expensive as the global supply diminishes.
Kazuhiro Yanagi from the Tokyo Metropolitan University, working with colleagues from across Japan, has now shown that carbon could be the perfect replacement.
Graphene sheets, consisting of a single atomic layer of carbon atoms in a honeycomb framework, can be rolled into a tube just a nanometer or so in diameter. These carbon nanotubes are highly conductive, mechanically strong, electrochemically stable and can show bright colors depending on how the sheet is rolled. Yanagi and his team have now shown that carbon nanotubes are also electrochromic.
The optical properties of carbon nanotubes can be altered by changing the density of electrons in the tube. Visible color change is achieved by applying a voltage of at least 2 V across tube when suspended in an electrolyte solution. Previous research has suggested that the nanotubes become photo-electrochemically unstable under these conditions. Yanagi and his colleagues, however, were able to prepare samples with good electrochemical stability using ionic liquids and density-gradient purifications. This combination reduced possible unexpected electrochemical reactions.
The novel electrochromic device consisted of a thin film of carbon nanotubes on a glass substrate. The team demonstrated the electrochromic function of their device using three different samples with different tube diameters. On application of a -3 V potential, 1.4 nm-diameter nanotubes went from a blue-green in color to yellow, 1.0 nm tubes turned from magenta to yellow-orange, and the initially yellow 0.84 nm sample changed to light yellow (see image). In all cases, the color returned to normal when the voltage was switched off. "Next, we would like to control the optical absorption causing the yellow color so we can get a highly transparent sheet of nanotubes, which could be important for electrochromic display applications," says Yanagi.
####
For more information, please click here
Contacts:
Committee for Public Relations
Tokyo Metropolitan University
1-1 Minami-Osawa, Hachioji-shi Tokyo, Japan 192-0397
Copyright © Tokyo Metropolitan University
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
Related News Press |
Thin films
Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024
Graphene/ Graphite
NRL discovers two-dimensional waveguides February 16th, 2024
Nanotubes/Buckyballs/Fullerenes/Nanorods/Nanostrings
Tests find no free-standing nanotubes released from tire tread wear September 8th, 2023
Detection of bacteria and viruses with fluorescent nanotubes July 21st, 2023
Discoveries
Chemical reactions can scramble quantum information as well as black holes April 5th, 2024
New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024
Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024
Materials/Metamaterials/Magnetoresistance
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024
Announcements
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||