Unveiling the relationship between the shortest Mn–Mn distance in manganese halide hybrids and their photoluminescence and scintillation properties

Abstract

Organic–inorganic hybrid manganese halides (OIMnHs) attract much attention in solid-state lighting and X-ray imaging, due to their eco-friendliness and outstanding photo/radioluminescent (PL/RL) properties. It has been reported that their luminescence performance is closely related to the distance between Mn centers. However, further research on their relationship is still needed, especially regarding their scintillation properties. In this work, four novel 0D OIMnHs (ted-C_n-ted)MnBr₄ (ted = triethylenediamine, n = 7–10) were synthesized using tailored (ted-C_n-ted)²⁺ cations. Benefiting from the large molecular size and rigidity of the cations, the [MnBr₄]²⁻ units are effectively separated, resulting in high PL quantum yields (PLQYs) and light yields. More importantly, after analyzing the synthesized compounds and the reported samples, the positive correlation between the shortest Mn–Mn distance in these OIMnHs and their PLQYs and light yields is unveiled, and OIMnHs with distances in the 9–11 Å range exhibit both superior PLQYs and light yields. Besides, a WLED device is fabricated by employing (ted-C₁₀-ted)MnBr₄, achieving high-quality illumination with 94% National Television Standards Committee (NTSC) color gamut coverage. This work not only deepens the understanding of structure–property relationships in OIMnHs, but also provides a theoretical foundation for designing advanced luminescent materials with high quantum efficiency and scintillation properties.