Jun 13, 2013
Capacitive touchpad demonstrates high-performance silver nanowire network
Silver nanowires in the form of percolating random networks are potential candidates for the development of flexible transparent electrodes. Unfortunately, purification of the nanowires after synthesis can be a tedious process. To tackle the issue, researchers have developed a simpler alternative, which uses a decanting technique for easy separation and straightforward elimination of most of the nanoparticle by-products. Using the purified material, the CEA-Liten team fabricated flexible transparent electrodes on plastic, with typically less than 25 ohm.sq–1 at 90% transparency in the visible spectrum. The electrodes were integrated in an operative transparent flexible touch sensor based on capacitive technology.
A decantation process allowed the group to remove directly the unwanted nanoparticles without major effort and waste of solvents.
The spray-coating deposition step used to fabricate the electrodes was realized at room temperature under ambient pressure and without annealing. The performance of the silver nanowire electrodes was comparable to the figure of merit for ITO, with additional benefits of high flexibility and transparency in the infrared spectrum.
Several interesting proof-of-concepts have already been realized using silver nanowires, such as the fabrication of thin-film heaters or integration into photovoltaic cells or PLEDs. Here, the team showed that the electrodes can be used to fabricate efficiently operative transparent sensors relying on capacitive technology.
The touchpad test device was able to give absolute responses (yes or no) for patterned specific areas, or modulate outputs such as LED intensity thanks to changes in capacitance during measurement (see multimedia).
Additional information can be found in the journal Nanotechnology.
About the author
The study was conducted by researchers at CEA-Liten in Grenoble, France, under the supervision of Dr Jean-Pierre Simonato, head of the CAN (Chemistry Applied to Nanomaterials) group. The team is investigating the synthesis and chemical functionalization of nanomaterials and their integration into devices.