The role of native defects in organic-inorganic hybrid zinc halide luminescent materials

Organic-inorganic hybrid metal halides have attracted considerable attention due to their structural diversity and promising optoelectronic properties. Although photoluminescence has been observed in hybrid zinc-based halides, the underlying emission mechanisms remain a topic of debate. In this study, we synthesized three phenylethylamine hybrid zinc halides, (C₈H₁₂N)₂ZnX₄ (X = Cl, Br, I), which feature zero-dimensional (0D) structures consisting of isolated [ZnX₄]²⁻ tetrahedral units surrounded by organic C₈H₁₂N⁺ cations. Upon photoexcitation, these compounds exhibit blue-white emission. Comprehensive experimental analysis suggests that the emission originates from intrinsic lattice defects, specifically zinc interstitials, and radiative transitions from the conduction band to deep-level states. Our findings confirm the presence of defect states in zinc-based halides and reveal that these defects simultaneously act as luminescence centers and limit the overall emission efficiency, contributing to the relatively low photoluminescence quantum yield (PLQY) observed in these materials.