Precise Modification\nof Organic Cations to Enhance\nthe Moisture Stability and Luminescence Efficiency of Mn-Based Halides

Eco-friendly organic–inorganic hybrid metal halides\n(OIMHs)\nare widely recognized as promising candidates for next-generation\nsemiconductor materials. However, achieving inherent moisture stability\nin OIMHs remains a significant challenge due to the highly hygroscopic\nnature of the halide structures. In response, a strategy to precisely\nmodify the organic cation (18-ACE: 4,13-diaza-18-crown 6-ether) was\ndeveloped by introducing hydrophobic benzyl groups into 18-ACE, forming\na protective layer that enhances the moisture stability of the OIMHs.\nSpecifically, benzyl groups were incorporated into 18-ACE to create\n18-ACE-Bn, which was then used as an organic component to construct\nzero-dimensional Mn-based (18-ACE)MnBr<sub>4</sub> and (18-ACE-Bn)MnBr<sub>4</sub>·H<sub>2</sub>O, exhibiting photoluminescence quantum\nyields (PLQYs) of 68.18% and 97.17%, respectively. Notably, (18-ACE-Bn)MnBr<sub>4</sub>·H<sub>2</sub>O demonstrates exceptional moisture stability\ncompared to (18-ACE)MnBr<sub>4</sub>, retaining 97% of its initial\nPLQY even after 180 days of exposure to 70% relative humidity. Molecular\ndynamics and density functional theory calculations indicate that\nthis superior stability is attributed to the terminal benzyl groups\nembedded within the inorganic framework, forming a compact structure\nwith abundant weak interactions. Leveraging the unique spectral characteristics\nof (18-ACE-Bn)MnBr<sub>4</sub>·H<sub>2</sub>O, a high-performance\nWLED with a wide color gamut of 125.2% NTSC (National Television Standard\nCommittee) was developed, highlighting its potential for backlight\ndisplay applications.