Solvent Tailoring Enables Centimeter-Scale Mn-Based Metal Halide Single-Crystal Films for High-Resolution X-ray...

The luminescence efficiency of Mn-based metal halides is critically governed by the solvent's electron-donating ability, which modulates the coordination environment around Mn2+ ions and ultimately dictates scintillation performance. However, systematic solvent-mediated design strategies remain underexplored, especially for large-area single-crystal films in high-resolution X-ray imaging. Herein, we employ organic manganese halide scintillators as a model system to investigate solvent effects across a broad spectrum, from acidic HBr to aprotic solvents with varying donor strengths (ACN, DMF, DMSO). Among these, HBr yields (TEMA)2MnBr4 with the highest PLQY (76%), attributed to the longest Mn-Mn distance (9.1356 Å) and a strong (001)-preferred orientation, as evidenced by sharp (00l) reflections. Under X-ray excitation, these crystals achieve a light output of 97% relative to LYSO, alongside outstanding photochemical stability under prolonged UV and X-ray exposure. Benefiting from the high transparency and minimal light scattering of the resultant large-area single-crystal films, we achieve a spatial resolution exceeding 29 lp mm-1 in direct X-ray imaging, surpassing most commercial and polycrystalline scintillators. This work establishes solvent engineering as a unified strategy for synergistically optimizing luminescence efficiency and crystal morphology, offering a design blueprint for high-performance Mn-based halide scintillators tailored to high-resolution imaging applications.