Unraveling the Near-Unity Narrow-Band Green Emission in Zero-Dimensional Mn<sup>2+</sup>-Based Metal Halides: A Case Study of (C<sub>10</sub>H<sub>16</sub>N)<sub>2</sub>Zn<sub>1–<i>x</i></sub>Mn<sub><i>x</i></sub>Br<sub>4</sub> Solid Solutions
Guojun Zhou, Zhiyang Liu, Jinglong Huang, Мaxim S. Моlokeev, Zewen Xiao, Chong‐Geng Ma, Zhiguo Xia
Abstract
Zero-dimensional (0D) Mn2+-based metal halides are potential candidates as narrow-band green emitters, and thus it is critical to provide a structural understanding of the photophysical process. Herein, we propose that a sufficiently long Mn–Mn distance in 0D metal halides enables all Mn2+ centers to emit spontaneously, thereby leading to near-unity photoluminescence quantum yield. Taking lead-free (C10H16N)2Zn1–xMnxBr4 (x = 0–1) solid solution as an example, the Zn/Mn alloying inhibits the concentration quenching that is caused by the energy transfer of Mn2+. (C10H16N)2MnBr4 exhibits highly thermal stable luminescence even up to 150 °C with a narrow-band green emission at 518 nm and a full width at half maximum of 46 nm. The fabricated white light-emitting diode device shows a high luminous efficacy of 120 lm/W and a wide color gamut of 104% National Television System Committee standard, suggesting its potential for liquid crystal displays backlighting. These results provide a guidance for designing new narrow-band green emitters in Mn2+-based metal halides.