• • MPAZnBr4 crystallizes in the monoclinic space group P21/c with unit cell parameters a = 6.65190 Å, b = 16.11210 Å, c = 13.79640 Å, β = 94.5700°, and Z = 4, yielding a calculated density of 2.394 g/cm3. This precise structural definition ensures batch-to-batch reproducibility, critical for scaling solution-processed optoelectronic devices.
• • The shortest Br···Br inter-cluster distance is 4.76 Å, which exceeds twice the van der Waals radius of Br (3.70 Å), confirming weak electronic coupling between [ZnBr4]2− tetrahedra. This isolation suppresses concentration quenching and enables high photoluminescence quantum yields, essential for efficient blue emitters in displays.
• • Photoluminescence peaks at 450 nm with a full width at half maximum of 135 nm (≈0.73 eV), corresponding to a deep-blue emission with CIE coordinates suitable for display backlights. The broad emission arises from triplet self-trapped excitons, as evidenced by a thermal quenching activation energy of 55 meV, which balances stability and efficiency.
• • The extensive hydrogen-bonding network confers exceptional stability: negligible photoluminescence decay after prolonged excitation or storage. This addresses a major industrial pain point—material degradation in encryption devices—enabling rewritable, switchable information encryption with long operational lifetimes.