A new method of processing nanomaterials could lead to faster and cheaper manufacturing of flexible thin film devices, from touch screens to window coatings.
Developed by engineers at Rutgers University-New Brunswick and Oregon State University, the "intense pulsed light sintering" method fuses nanomaterials in seconds. It uses high-energy light over an area nearly 7,000 times larger than a laser.
A new study on the method published in RSC Advances shows that fusing silver nanoparticles into electrically-conducive structures can be accomplished at temperatures of 150 degrees Celsius (302 degrees Fahrenheit). That's a sharp reduction from the existing method of pulsed light fusion, which uses temperatures around 250 degrees Celsius (482 degrees Fahrenheit).
The use of lower temperatures opens the possibility of employing low-cost, temperature-sensitive plastic substrates in flexible devices without the danger of damaging them. These include polyethylene terephthalate (PET) and polycarbonate.
Fused silver nanomaterials are used to conduct electricity in devices like radio-frequency identification (RFID) tags, display devices and solar cells. Fusing conductive nanomaterials onto flexible substrates, such as plastics and other polymers, makes it possible to create flexible versions of these devices.
Having worked with nanowires and nanospheres, the researchers next plan to employ additional nanomaterial shapes -- such as triangles and flat flakes -- to explore the possibility of lowering fusion temperatures even further.
In a separate study, the team demonstrated pulsed light sintering of a semiconductor, copper sulfide nanoparticles, to make films less than 100 nanometers thick. Current methods take minutes to hours to perform the fusion; the Rutgers and Oregon State engineers did it in two to seven seconds, according to senior author Rajiv Malhotra. This could speed up the manufacture of copper sulfide thin films used in window coatings that control solar infrared light, transistors and switches.
"Pulsed light sintering of nanomaterials enables really fast manufacturing of flexible devices for economies of scale," said Malhotra, an assistant professor in the Department of Mechanical and Aerospace Engineering at Rutgers-New Brunswick.