UNO Alumnus Shares “No-Touch” Touch Screen Research


On Friday, UNO alumnus and corporate fellow at the DOW Chemical Company Dr. Peter Trefonas visited the chemical sciences building to share his research on a new type of display.

“Suppose each pixel could emit light,” said Trefonas, “but could also detect light.”

Hosted by Advanced Materials Research Institute (AMRI) director Dr. John Wiley, the event drew a few dozen students and faculty.  Said physics student Guarav Gyawali of Trefonas’ work, “I think it’s really cool. I thought [the talk] was going to be really interesting and it actually was.”

Trefonas first detailed his professional career, which has always been rooted in electronic materials research and development. Then he discussed his work of the last five years with the University of Illinois Urbana-Champaign.

The technology in question is “novel emissive QLED displays based on heterojunction nanoparticles which can display bidirectional functionality … at very low voltages,” said Trefonas.

“QLED”, or quantum light-emitting diode, displays are comparable to the OLED displays in many high-end modern televisions and phones, but “quantum” implies that the pixels are made of quantum dots. An electric current flows into the quantum dots, causing them to emit light. The color of the light – red, blue or green – depends on the size of the dot.  QLED displays already exist, but screens that can not only emit light but can perceive changes in light are unprecedented.

Trefonas spent the majority of his presentation using diagrams and graphs to explain the structure of the double heterojunction nanorods that allowed this idea to become a reality. Heterojunction means that the nanorods – microscopic rod-shaped objects – are made of two materials: in this case, cadmium sulfide and zinc selenide. A process of chemical synthesis is required to produce them.

Overall, their QLED display was also brighter than any other existing display at 101,000 candelas per meter squared. That brightness is comparable to the brightness of 101,000 candles burning at once concentrated over the space of a bath towel. For comparison, a car headlight has the brightness of 100,000 candelas. And according to Trefonas, his team wasn’t even expecting the pixels to be this bright.

Trefonas also shared short clips of the QLED bidirectional displays in action. So far, his research group has developed small, simple screens that display one color at a time in large blocks. He explained that the displays can be programmed to work differently. For example, a laser pointed at the screen could turn a line of pixels on in a pattern. The pixels turned off again in the same order after five seconds.

In one example, Trefonas said, “We programmed it so that when [the pixels] detect light, [they’re] gonna get brighter.” His idea was that a television screen could adjust its brightness automatically based on the brightness in the room, pixel by pixel, depending on which parts of the screen were covered in shadow or bright spots of light. The result would be a television with a uniform brightness across the screen, regardless of how uneven the lighting in the room is.

“I’ve always been interested in bidirectional display,” said Trefonas. “The idea that diodes could emit and detect light was first discovered in the 1970s.” He gave the example of old Macintosh laptops, which once featured the ability to beam information to each other via rapidly blinking red lights. The device that transmitted the data was capable of simultaneously receiving data from the other computer.

“Apple supported this idea, which no one ever used,” Trefonas said.

But according to Trefonas, the potential applications for his team’s new display will be useful in a variety of ways.

“I could make a touchless screen display,” he said, since pixels wouldn’t need to be touched to be able to detect the shadow of a finger hovering over them.

He also mentioned placing two displays against each other to transfer data for massively parallel communication. “We could get to a really fast two-way data communication,” he said.

He suggested other potential applications, like electronic whiteboards and screens that can detect different colors of light from a “light stylus.” Art, video games, and the way that we interact with everyday objects could all be affected by further development on his team’s research.  

“It needs a lot more work to turn into a real display,” said Trefonas. “It’s at least five to 10 years off in technology.”

He left the audience to ponder a quote from Theodore Hook that motivates him: “The best way to predict the future is to invent it yourself.”