Researchers at the University of Würzburg have developed individually addressable organic light-emitting diode (OLED) pixels measuring just 300 × 300 nanometers—smaller than the wavelength of visible light and representing the smallest individually controllable OLED pixels reported to date.

The Core Innovation

The key challenge in scaling OLEDs down to nanoscale dimensions is that sharp electrode edges create intense local electric fields, leading to unbalanced charge injection, poor efficiency, and device failure through metallic filament formation. The team solved this by introducing an insulating layer that selectively covers the electrode edges while leaving a precisely defined nanoaperture at the center. This ensures charge carriers inject uniformly through flat regions with homogeneous electric fields, rather than concentrating at problematic edges and corners.

Performance Achievements

The nano-OLEDs demonstrate remarkable stability and performance. They achieve external quantum efficiencies around 1%, maximum brightness of 3,000 cd/m², and response times exceeding standard video frame rates (>60 fps). The devices use gold patch antennas as bottom electrodes, which serve dual purposes: efficient hole injection and plasmonic light extraction. By coupling molecular emission to plasmonic modes of the nanoscale gold antenna, the researchers achieved efficient light outcoupling despite the extremely small pixel size, where conventional emission would be severely limited by the (pixel size/wavelength)² relationship.

Broader Impact

This work represents a significant advance for ultra-high-density displays (potentially exceeding 10,000 pixels per inch) for augmented and virtual reality applications, as well as for photonic integrated circuits. The nanoaperture fabrication process proved highly reproducible with over 90% device yield, demonstrating practical scalability. While further optimization of organic layer stacks and antenna designs could improve performance, the demonstrated approach provides a clear path to overcome fundamental electronic and optical bottlenecks in nanoscale optoelectronic devices.

Source: https://www.science.org/doi/10.1126/sciadv.adz8579

In popular media: - https://www.notebookcheck.net/Nanoscale-OLEDs-scientists-reduce-the-size-of-OLED-pixels-to-just-300-nm.1148743.0.html - https://www.tomshardware.com/monitors/researchers-create-worlds-smallest-pixel-measuring-just-300-nanometers-across-could-be-used-to-create-a-1080p-display-measuring-1mm