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

Abstract

Er³⁺-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 Cs₃ErCl₆ nanocrystals (NCs)-based LEDs via a synergistic strategy of Sb³⁺/Y³⁺ co-doping and camphor ligand modification. Y³⁺ doping modulates lattice symmetry, inducing Stark splitting of the Er³⁺ energy level and enhancing luminescence intensity. Sb³⁺ introduction triggers efficient self-trapped excitons emission at 530 nm, whose energy levels match Er³⁺ states to boost energy transfer efficiency. Subsequently, camphor ligand exchange passivates Er³⁺-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 Cs₃Er_0.7Y_0.3Cl₆: Sb³⁺ 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.