A team of physicists at Julius-Maximilians-Universität Würzburg has engineered an organic-light-emitting diode (OLED) pixel sized at only 300 × 300 nm, smaller than the wavelength of light it emits, and capable of matching the brightness of a conventional 5 × 5 µm OLED pixel, tells this article on The Register.
Their prototype emits orange light and features a gold nano-antenna base measuring 300 × 300 × 50 nm. A major challenge was uneven electric fields at the nano-scale, where the antenna corners concentrate current, causing gold atoms to migrate into the emitting layer and short-circuit the device.
To mitigate this, the researchers wrapped the antenna in a hydrogen silsesquioxane insulating ring, leaving a 200 nm circular aperture for light emission. This structure suppresses filament formation and enables stable operation under ambient conditions for at least two weeks.
Scaling down to 300 nm enables pixel densities so extreme that a full HD (1920 × 1080) display could fit into just one square millimeter. That kind of density has implications for augmented- and virtual-reality (AR/VR) wearables, where display modules must be ultra-compact.
However, there are limitations: current efficiency is only about 1%, and the device only produces a single color (orange) at present.
Besides, turning a single nano-pixel into a full array and commercial product remains a major engineering challenge. This breakthrough pushes the boundaries of optics and display engineering. While still early, the nano-OLED pixel demonstrates how the laws of classical optics can be stretched via clever nano-electronics and may eventually enable ultra-dense, wearable, high-resolution displays.