A research analysis in Science and Technology of Advanced Materials has revealed that carbon nanotubes show potential, but have many challenges in manufacturing wearable, flexible electronics.
Wearable, stretchable and flexible optoelectronic devices are currently being developed by scientists. One example of the devices being developed are body sensors that are capable of providing consistent monitoring of an individual’s blood pressure.
There is still discussion regarding the best materials to manufacture these devices. Carbon nanotubes (CNTs) show potential, but still have some issues.
Ying Zhou and Reiko Azumi from Japan’s National Institute of Advanced Industrial Science and Technology analyzed the latest work on the use of carbon nanotubes in manufacturing a significant component of optoelectronic devices known as transparent conductive films (TCFs). TCFs are a material’s thin films and they are electrically conductive and optically transparent.
By 2025, the market for TCFs is expected to reach 1.2 billion dollars. Indium tin oxide (ITO) is currently used to manufacture TCFs. ITO is considered to have remarkable conductive properties, however the only disadvantage is that its poor flexibility prevents it from being ideal for wearable devices.
A number of ITO alternatives to develop TCFs are being analyzed by researchers. This investigation highlights that carbon nanotube-based devices are promising.
CNTs are cylindrical tubes that are nanosized with high theoretical electrical conductivity. There has been a drop in the prices of CNTs because of their commercialization for applications such as conductors, batteries, sports equipment and water filtration systems. Advances in the manufacturing processes can lead to further reduction in prices.
Wearable touch panels and other sensing devices are best suited for use in CNT-based transparent conductive films. CNTs are already being used by two companies in Japan to manufacture touch panels for mobile electronics.
Another potential application for CNT-based TCFs are organic LEDs (OLEDs), which are already used to develop lighter, thinner and more efficient TV screens. Other metals, like metal nanowires, that are used in their manufacture comprise higher conductivity and transparency, resulting in improved performance.
“Based on the overview of the fabrication, properties and possible applications of CNT-based TCFs, it can be concluded that current CNT-based TCFs still do not meet the demands of performance/cost for industrial use,” write the researchers in their review published in the journal Science and Technology of Advanced Materials.
Manufacturing costs need to be reduced while their conductivity and transparency need to be improved, they say.
The researchers recommend that investigations in the future should focus on the stretchability and flexibility of CNT-based TCFs by enhancing their conductivity and manufacturing in order to prove them to be valuable contenders for wearable optoelectronics.