The internet runs on light at 1.55 micrometers. This specific infrared wavelength, in the so-called C-band of optical fiber communications, is the lowest-loss transmission window of standard silica fibers — the channel that carries data across continents and under oceans. Generating light efficiently at this wavelength is therefore one of the most important challenges in optoelectronics.
Now, researchers at Soochow University and Macau University of Science and Technology have demonstrated a new approach: a film of erbium-doped perovskite quantum dots that self-assemble into ordered superstructures, achieving record electroluminescence efficiency at the critical telecom wavelength. The work was published July 11 in Nature Communications.
“Our results show that controlling the spatial arrangement of quantum dots at the mesoscale, not just their chemical composition, is a powerful strategy for improving device performance,” said corresponding author Ya-Kun Wang of Soochow University’s Institute of Functional Nano and Soft Materials.
The problem of random packing
Erbium ions (Er³⁺) have long been known to emit at approximately 1.54 micrometers, the product of an atomic transition within the ion’s 4f electron shell. Embedding Er³⁺ in cesium lead chloride (CsPbCl₃) perovskite quantum dots — nanoscale semiconductor crystals — produces a material that can, in principle, convert electricity into light at this wavelength. The problem has been getting the dots to do so efficiently.
Two obstacles stood in the way. First, conventional synthesis methods produce quantum dots of uneven size; polydisperse nanocrystals cannot pack into ordered films. Second, when deposited into devices, the randomly packed dots create pathways for charge leakage and foster non-radiative recombination — processes that waste energy as heat rather than producing light.
The Soochow team solved both problems with a single chemical trick. They used myristoyl chloride as a slow-release source of chloride ions during synthesis, which gave them a population of highly uniform, monodisperse quantum dots. At the same time, the reaction generated amide-containing molecules that capped the surfaces of the quantum dots. These amide groups carry both a hydrogen-bond donor (N–H) and an acceptor (C=O), allowing adjacent quantum dots to link together through directional N–H···O=C hydrogen bonds during film deposition.
The result was a mesoscale ordered assembly: the cubic quantum dots stacked face-to-face, like well-stacked building blocks, forming ordered arrays spanning hundreds of nanometers to micrometers. The structure was confirmed by two-dimensional grazing-incidence small-angle X-ray scattering at the Suzhou Institute of Nano-Tech and Nano-Bionics.
Record performance
In an LED device, the ordered quantum dot films achieved an external quantum efficiency of 3.75% and a maximum radiance of 323 milliwatts per steradian per square meter at 1.55 micrometers — roughly 10 times brighter than disordered control films. The operational stability also improved markedly: the devices retained 50% of their initial brightness after 197 minutes (the T50 lifetime), approximately seven times longer than the disordered controls.
The 3.75% EQE is a record for Er³⁺-doped perovskite electroluminescence at the telecom wavelength. The authors attribute the improvement to the suppression of trap states — defects that capture charge carriers and cause non-radiative recombination — and to improved charge transport through the ordered film.
“This is a proof of concept that hydrogen-bonding-directed assembly can solve the fundamental packing problem in quantum dot films,” said co-first author Hua-Hui Li. “The assembly gives us control over the film structure that is simply unavailable with conventional deposition.”
The road ahead
The achievement is significant for the field of solution-processed photonics. Perovskite quantum dots are attractive for next-generation displays and lighting because they can be synthesized in solution and deposited at low cost. Extending that advantage to telecom-wavelength emitters could eventually enable cheaper, simpler optical transmitters for fiber-optic networks and on-chip interconnects.
But substantial hurdles remain. The 3.75% EQE, while a record for this material system, is modest compared to commercial III-V semiconductor lasers (InGaAsP/InP), which can exceed 50% wall-plug efficiency. The operational stability of 197 minutes — approximately three hours — is far too short for any practical application; perovskite quantum dots in general suffer from degradation in the presence of oxygen, moisture, and the electric fields inside operating devices. And the material contains lead, a known neurotoxin that complicates any pathway to commercial deployment under the European Restriction of Hazardous Substances directive and similar regulations.
Nevertheless, the work demonstrates that a decade-old dream — electrically driven erbium emission from solution-processed nanocrystals — is within reach, and that the key may lie not in finding a better material, but in arranging the material they already have.
Source: Li, H.-H., Pan, J.-L., Pan, Y.-Y. et al. “Mesoscale ordered assembly of Er³⁺-doped quantum dots enables efficient 1.55 μm electroluminescence.” Nature Communications (2026). DOI: 10.1038/s41467-026-75429-3