Dual Circularly Polarized Luminescence and Room‐Temperature Phosphorescence in Hybrid Indium‐Based Perovskites

ABSTRACT Circularly polarized luminescence (CPL)‐active materials with lead‐free composition, near‐unity photoluminescence quantum yield (PLQY), and a large luminescence dissymmetry factor (g lum ) are critical for advanced optoelectronic applications like 3D displays and multi‐level information encryption. However, achieving this combination in 0D chiral metal halides remains challenging, as efficient chirality transfer to localized emissive states is often limited. Here, we demonstrate a synergistic strategy to overcome these limitations via diamino‐functionalized chiral cations R / S ‐MPZ 2+ (where MPZ is 2‐methylpiperazine) and Sb 3+ doping. The dual‐site hydrogen‐bonding R / S ‐MPZ 2+ strengthens the organic–inorganic interface, enhancing chirality induction at the emissive sites. Concurrently, Sb 3+ incorporation modulates the localized excited‐state landscape in the soft 0D lattice and enhances spin–orbit coupling, facilitating radiative recombination and opening an efficient ISC‐enabled delayed channel. This design yields enantiopure ( R / S ‐MPZ) 2 In 1− x Sb x Cl 7 ( x = 0.0144) single crystals that integrate near‐unity PLQY (99.53%), pronounced CPL (|g lum |∼3.1 × 10 −2 ), and long‐lived room‐temperature phosphorescence (RTP) (τ ∼ 84 ms). This integrated PLQY–CPL–RTP portfolio highlights a balanced multifunctional chiroptical emitter. Leveraging this prompt–delayed dual‐emission behavior, we demonstrate multi‐level anti‐counterfeiting and phosphor‐converted circularly polarized LEDs (CP‐LEDs). This work offers an effective strategy for developing high‐performance lead‐free CPL materials, thereby facilitating their applications in polarized light sources and information encryption within advanced optoelectronics.