Ultra‐Efficient Circularly Polarized Luminescence in Chiral In‐Sb Chlorides with Near‐Unity Quantum Yield

ABSTRACT Circularly polarized luminescence (CPL) materials hold significant promise in advanced optoelectronics. However, it still remains challenging to obtain chiral metal halides with simultaneously a large luminescence dissymmetry factor ( g lum ) and high photoluminescence quantum yield (PLQY). Inspired by the intriguing luminescence properties of heterometallic‐doping complexes, we successfully synthesized chiral indium‐antimony halide hybrids, ( R / S ‐MPZ) 2 In 1‐x Sb x Cl 7 ( R / S ‐1 ) (MPZ = 2‐Methylpiperazine, x ≈ 0.02), where the alloying of Sb 3+ ions significantly enhances PLQY and optimizes the distortion of metal halide octahedra, thereby synergistically improving the g lum . As a result, R ‐1 exhibits excellent CPL performance with PLQY and | g lum | values up to 98.2% and 0.1, respectively. The high figure of merit of 9.82 × 10 −2 significantly surpasses those of the reported indium‐based CPL materials. Furthermore, the resulting circularly polarized light‐emitting diode exhibits a high | g lum | value of 9.3 × 10 −3 , being superior to most reported CPL‐active materials. This work provides a robust strategy for addressing the synergistic enhancement between g lum and PLQY in CPL systems, offering a high‐performance polarized light source for quantum communication and optical encryption.