  Miniaturization of light-emitting diodes (LEDs) can enable high-resolution
augmented and virtual reality displays and on-chip light sources for
ultra-broadband chiplet communication. However, unlike silicon scaling in
electronic integrated circuits, patterning of inorganic III-V semiconductors in
LEDs considerably compromises device efficiencies at submicrometer scales.
Here, we present the scalable fabrication of nanoscale organic LEDs
(nano-OLEDs), with the highest array density (>84,000 pixels per inch) and the
smallest pixel size (~100 nm) ever reported to date. Direct nanomolecular
patterning of organic semiconductors is realized by self-aligned evaporation
through nanoapertures fabricated on a free-standing silicon nitride film
adhering to the substrate. The average external quantum efficiencies (EQEs)
extracted from a nano-OLED device of more than 4 megapixels reach up to 10%. At
the subwavelength scale, individual pixels act as electroluminescent meta-atoms
forming metasurfaces that directly convert electricity into modulated light.
The diffractive coupling between nano-pixels enables control over the far-field
emission properties, including directionality and polarization. The results
presented here lay the foundation for bright surface light sources of dimension
smaller than the Abbe diffraction limit, offering new technological platforms
for super-resolution imaging, spectroscopy, sensing, and hybrid integrated
photonics.
