Unraveling the Ultrafast Self-assembly and Photoluminescence in Zero-Dimensional Mn2+-Based Halides with Narrow-Band Green Emissions

The discovery of narrow-band luminescent materials remains an immense challenge to optimize the performance of white light-emitting diodes (LEDs). So far, the zero-dimensional (0D) Mn²⁺-based halides with near-unity narrow-band emissions have emerged as a class of promising phosphors in solid-state displays, but the related large-scale synthesis strategies have not been proposed and evaluated. Herein, we report an in situ synthetic process of 0D Mn²⁺-based halides and utilize (C₂₀H₂₀P)₂MnBr₄ as a case to investigate the photoluminescence characteristics and the structural essence of ultrafast self-assembly. The bright green emission peak at 523 nm with a full width at half maximum of 48 nm for (C₂₀H₂₀P)₂MnBr₄ is attributed to the d–d transition (⁴T₁–⁶A₁) of tetrahedrally coordinated [MnBr₄]^2– centers, and the fabricated white LED device shows a wide color gamut of 103.7% National Television System Committee (NTSC) standard. Remarkably, the experimental and theoretical results indicate that there are hydrogen bonding of C–H···Br and weak van der Waals interactions between [C₂₀H₂₀P]⁺ and [MnBr₄]^2–, resulting in the root for the realization of ultrafast self-assembly in 0D Mn²⁺-based halides. This work reveals a feasible and general synthesis method for preparing 0D Mn²⁺-based halides, thereby providing a possibility for their industrial application in solid-state displays.

https://doi.org/10.1021/acsaelm.1c00606