Circularly Polarized 1540 nm Short‐Wave Infrared Electroluminescence from Er‐Based Halide LEDs with 3.06% Record Efficiency

ABSTRACT Er 3+ ‐doped 1540 nm light‐emitting diodes (LEDs) are critical components in optical communications C‐band, non‐trunk communication, bioimaging, and sensing. However, integrating high luminous efficiency with tailored circularly polarized luminescence (CPL) in such LEDs remains a critical challenge. Here, we demonstrate efficient 1540 nm short‐wave infrared (SWIR) electroluminescence with distinct CPL in Cs 3 ErCl 6 nanocrystals (NCs)‐based LEDs via a synergistic strategy of Sb 3+ /Y 3+ co‐doping and camphor ligand modification. Y 3+ doping modulates lattice symmetry, inducing Stark splitting of the Er 3+ energy level and enhancing luminescence intensity. Sb 3+ introduction triggers efficient self‐trapped excitons emission at 530 nm, whose energy levels match Er 3+ states to boost energy transfer efficiency. Subsequently, camphor ligand exchange passivates Er 3+ ‐related defects, increasing the 1540 nm photoluminescence quantum yield to 35.7% and endowing NCs with CPL (asymmetry factor: −3.67 × 10 −2 ) via camphor's chiral structure. SWIR LEDs based on camphor‐modified Cs 3 Er 0.7 Y 0.3 Cl 6 : Sb 3+ NCs exhibit a record‐high external quantum efficiency of 3.06% at 1540 nm, and first, demonstrate electrically‐driven circularly polarized 1540 nm emission with asymmetry factor of −3.08 × 10 −2 . This work presents a synergistic doping‐ligand strategy for Er‐based halide optoelectronics, offering a versatile platform to develop high‐performance long‐wavelength devices with integrated efficient emission and tailored polarization, crucial for advancing next‐generation optical communication and bioimaging.