Technologists have designed a method to fabricate a fully 3D-printed, flexible organic light-emitting diode (OLED) display. The development could lead to a faster means of production together with the printing of lower cost screens.
The development comes from the University of Minnesota and the potential with the technology is that people could, one day, print their won OLED screens at home rather than be reliant upon expensive microfabrication processes, where screens need to be purchased from retailers. The screens are used for televisions, computer monitors and for various handheld devices like tablets and smartphones.
An OLED screen is composed of a layer of organic materials, situated between two electrodes and deposited on a substrate. The organic molecules are electrically conductive, ranging from insulators to conductors.
The OLED screens tested out using the 3D printing are comparable with screens produced through more conventional production. The printed screens are lightweight, power-efficient, thin and flexible, and they offer a wide viewing angle and high contrast ratio. The printed screens were not equivalent to the highest available on the market, but the researchers hope to create screens with higher resolution with improved brightness as their technology progresses.
The biggest complexity with the technology was with ensuring the uniformity of the light-emitting layers. This was overcome by custom building a 3D printer at a relatively low-cost. The printer is also portable, making it suitable for eventual home use.
The following video shows the printer in action (opens in YouTube).
The additive manufacturing process used two different modes of printing in order to print six device layers, including the electroluminescent diodes. With the combination of the two methods, the electrodes, interconnects, insulation, and encapsulation were all extrusion printed; and the active layers were spray printed.
Both techniques utilized the same 3D printer and the printing process took place at room temperature. The display prototype was about 1.5 inches on each side and had 64 pixels (as the smallest single components of the displayed digital images). Every pixel was checked to show that it worked and was capable of displaying light.
The display was also flexible and in tests it was bent 2,000 times without any evident affect on its performance. This makes the types of screens that be printed suitable for soft electronics and wearable devices.
The development of the printer appears in the journal Science Advances, where the paper is titled “3D-printed flexible organic light-emitting diode displays.”
