Mesoscale ordered assembly of Er(3+)-doped quantum dots enables efficient 1.55 µm electroluminescence.

Efficient, electrically driven 1.55 µm light sources are highly desirable for telecom-band emission, on-chip optical sensing, and integrated near-infrared photonics, yet their realization remains a grand challenge. Direct integration of Er into semiconducting perovskite quantum dots (QDs) offers superior potential by enabling intrinsic charge transport, but this pathway is stifled by kinetic barriers that yield polydisperse nanocrystals and random packing, collectively inducing leakage and quenching. Here, we report mesoscale ordering of Er-doped CsPbCl QDs with efficient 1.55 µm electroluminescence by coupling kinetically controlled synthesis with hydrogen-bonding-directed assembly. Using myristoyl chloride as a slow-release chloride source, we synthesize monodisperse QDs while in-situ generating amide ligands that form interdot N-H···O = C hydrogen-bonding networks. These networks direct assembly into mesoscale ordered assemblies with preferential {100} face-to-face orientation. The resulting architecture yields a record EQE of 3.75% and maximum radiance of 323.31 mW sr m, 10 times higher than the disordered controls, with an operational stability of 197 minutes ( 7-fold improvement). This establishes hierarchically ordered semiconductor assemblies as promising candidate for telecom-band optoelectronics.