Researchers in the US have used a custom printer to print a flexible OLED (organic light-emitting diode) screen entirely in 3D.
According to the Twin Cities team at the University of Minnesota, the advances could result in low-cost OLED screens that can be produced by anyone at home using 3D printers. The research is detailed in scientific progress.
The OLED display technology converts electricity into light using an organic material layer. OLEDs function as high-quality digital displays that can be flexibly made and used in large-scale devices and wearable electronics. OLED displays are lightweight, energy efficient, thin and flexible and offer a wide viewing angle and high contrast ratio.
“OLED displays are typically produced in large, expensive, ultra-clean manufacturing facilities,” said Michael McAlpine, a professor in the University of Minnesota Kuhrmeyer Family Chair in the Department of Mechanical Engineering and the study’s senior author. “We wanted to see if we could put all that together and print an OLED screen on our tabletop 3D printer, which was custom built and cost about the same as a Tesla Model S.”
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The group had previously attempted to 3D print OLED screens, but struggled with the uniformity of the luminescent layers. Other groups printed displays in part, but also relied on spin coating or thermal evaporation to deposit certain components and create functional devices.
In this new study, the University of Minnesota research team combined two different printing modes to print the six device layers, resulting in a fully 3D-printed, flexible organic light-emitting diode display. The electrodes, connections, insulation and encapsulation were all printed by extrusion, while the active layers were spray printed with the same 3D printer at room temperature. The display prototype was about 1.5 inches on each side and had 64 pixels that worked and rendered light.
“I thought I’d get something, but maybe not a fully working screen,” said Ritao Su, the study’s lead author and a postdoctoral researcher at MIT. “But then all the pixels seem to work and I can display the text I’ve designed. My first reaction was ‘It’s real!’ I couldn’t sleep all night.”
Su said the 3D-printed screen was also flexible and can be packaged in an encapsulation material, which could make it useful for a wide variety of applications.
“The device showed relatively stable emission over the 2000 bending cycles, suggesting that fully 3D-printed OLEDs could potentially be used for important applications in soft electronics and wearable devices,” Su said.
The researchers said the next steps are to 3D print OLED displays with higher resolution and improved brightness.
“The nice thing about our research is that manufacturing is completely built-in, so we’re not talking about some ‘pie in the sky’ vision in 20 years,” McAlpine said. “This is something that we actually made in the lab, and it’s not hard to imagine that in a few years you could translate this to printing all kinds of displays yourself at home or on the go, on a small portable printer.”
