Researchers Predict Ultra-Resolution Displays to Come, Thanks to These Nano-Scale OLEDs

Researchers from ETH Zurich, the University of Alberta, the Indian Institute of Science, and Huazhong University of Science and Technology have developed the smallest organic light-emitting diodes (OLEDs) to date — taking the technology down to the nano-scale.

"The diameter of the most minute OLED pixels we have developed to date is in the range of 100 nanometres, which means they are around 50 times smaller than the current state of the art," explains co-author Jiwoo Oh, a doctoral student in ETH Zurich's nanomaterial engineering research group. That, co-author Tommaso Marcato says, means a big leap in potential display resolution: "in just one single step, the maximum pixel density is now around 2,500 times greater than before."

OLEDs are a common choice for high-end displays, allowing for control over brightness down to a per-pixel level — contrasted with LCD panels, which are only capable of brightness control over a larger area, leading to poorer contrast and less ability to handle scenes with a high dynamic range. The smaller the OLEDs, the more tightly they can be packed — and the higher the resolution of the finished display.

A light-up logo built using the team's nano-OLEDs, measuring around the size of a human cell and with each pixel only 200 nanometers across, shows just how tiny the OLEDs are — and the smallest the team has yet made are half the size of that.

It's not just about ultra-high resolution displays, though: the researchers say the same technology could be used in scientific imaging, too, delivering a big boost in resolution to optical microscopes. "A nano-pixel array as a light source could illuminate the most minute areas of a sample," Chih-Jen Shih, professor of technical chemistry at ETH Zurich, proposes. "The individual images could then be assembled on a computer to deliver an extremely detailed image."

There's even the potential for the OLEDs to live at the heart of ultra-compact laser sources, thanks to the way each pixel is positioned at the edges of the diffraction limit of visible light — causing them to interact in a way that allows the researchers to control the angle at which light is emitted. "In future," Marcato predicts, "it will also be possible to bundle the light from a nano-OLED matrix in one direction and harness it to construct powerful mini lasers."

The team's work has been published in the journal Nature Photonics under open-access terms; work is ongoing in developing a way to control each OLED individually for use in a dynamic display system.

Main article image courtesy of Amanda Paganini/ETH Zurich.