Lantern‐Shaped Structure Induced by Racemic Ligands in Red‐Light‐Emitting Metal Halide with Near 100% Quantum Yield and Multiple‐Stimulus Response

Organic‐inorganic metal halides (OIMHs) have become a research hotspot in recent years due to their excellent luminescent properties and tunable emission wavelengths. However, the development of efficient red‐light‐emitting OIMHs remains a significant challenge. This work reports three Mn‐based OIMHs derived from 1‐methyl‐1,2,3,4‐tetrahydroisoquinoline hydrobromide: racemic one (Rac‐TBM) and chiral ones (R‐TBM and S‐TBM). As a result of the synergism of chiral organic ligands inducing a unique lantern‐shaped hybrid structure containing both tetrahedra and octahedra, Rac‐TBM exhibits red‐light emission with near‐unity luminescence quantum yield. In comparison, the chiral counterparts R/S‐TBM display strong green emission and circularly polarized luminescence (CPL) with a glum value up to ± 2.5 × 10‐2. Interestingly, a mixture of R‐ and S‐TBM can transform into Rac‐TBM, successfully achieving a sensitive and reversible switch between red light of octahedra and green light of tetrahedra under external stimuli. The outstanding luminescent properties allow Rac‐TBM to be utilized not only for X‐ray radioluminescence with a detection limit down to 46.29 nGys‐1, but also for advanced information encryption systems to achieve leak‐proof decryption.