Downscaling micro- and nano-perovskite LEDs.

Many technological breakthroughs in electronics and photonics were made possible by downscaling-the process of making elementary devices smaller in size. The downsizing of light-emitting diodes (LEDs) based on III-V semiconductors led to micro-LEDs, an 'ultimate technology' for displays. However, micro-LEDs are costly to produce and they exhibit severe efficiency losses when the pixel sizes are reduced to about 10 μm or less, hindering their potential in commercial applications. Here we show the downscaling of an emerging class of LEDs based on perovskite semiconductors to below the conventional size limits. Micro- and nano-perovskite LEDs (micro-PeLEDs/nano-PeLEDs) with characteristic pixel lengths from hundreds of micrometres down to about 90 nm are demonstrated, through a localized contact fabrication scheme that prevents non-radiative losses at the pixel boundaries. For our near-infrared (NIR) and green micro-PeLEDs, average external quantum efficiencies (EQEs) are maintained at around 20% across a wide range of pixel lengths (650 to 3.5 μm), exhibiting minimum performance reduction on downsizing. Our nano-PeLEDs with characteristic pixel lengths down to about 90 nm represent the smallest LEDs reported, enabling a record-high pixel density of 127,000 pixels per inch (PPI) among all classes of LED arrays. Our demonstration showcases the strength of micro- and nano-PeLEDs as a next-generation light-source technology with unprecedented compactness and scalability.