Organic Cation Modulation in Manganese Halides to Optimize Crystallization Process and X‐Ray Response Toward Large‐Area Scintillator Screen

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 44; pp. e2403234 - n/a
• Main Authors: Wang, Shuo, Chen, Huanyu, Xu, Youkui, Peng, Guoqiang, Wang, Haoxu, Li, Qijun, Zhou, Xufeng, Li, ZhenHua, Wang, Qian, Jin, Zhiwen
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-11-2024
• Subjects: blade coating; Cations; Crystallization; Excitons; Halides; In situ measurement; Luminescence; Manganese; Modulation; Optical properties; organic cation; Photon scatter; Photons; Scintillation counters; scintillator screen; Screens; Spatial resolution; Steric hindrance; crystallization; organic cation; scintillator screen; blade coating
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202403234

Manganese halides are one of the most potential candidates for large‐area flat‐panel detection owing to their biological safety and all‐solution preparation. However, reducing photon scattering and enhancing the efficient luminescence of scintillator screens remains a challenge due to their uncontrollable crystallization and serious nonradiative recombination. Herein, an organic cation modulation is reported to control the crystallization process and enhance the luminescence properties of manganese halides. Given the industrial requirements of the X‐ray flat‐panel detector, the large‐area A2MnBr4 screen (900 cm2) with excellent uniformity is blade‐coated at 60 °C. Theoretical calculations and in situ measurements reveal that organic cations with larger steric hindrance can slow down the crystallization of the screen, thus neatening the crystal arrangement and reducing the photon scattering. Moreover, larger steric hindrance can also endow the material with higher exciton binding energy, which is beneficial for restraining nonradiative recombination. Therefore, the BPP2MnBr4 (BPP = C25H22P+) screen with larger steric hindrance exhibits a superior spatial resolution (>20 lp mm−1) and ultra‐low detection limit (< 250 nGyair s−1). This is the first time steric hindrance modulation is used in blade‐coated scintillator screens, and it believes this study will provide some guidance for the development of high‐performance manganese halide scintillators.
This work emphasizes the huge impact of organic cations with different steric hindrances on crystallization during blade coating. Both photon scattering and nonradiative recombination are restrained by employing larger‐steric‐hindrance molecules. Finally, the industry‐level scintillator screen (30 × 30 × 0.2 cm3) exhibits superb spatial solution (> 20 lp mm−1) and excellent stability in harsh environments.