Concurrently Achieving Excellent Anti‐Thermal Quenching and Ultrahigh Light Yield in Scintillation of Hybrid Manganese Halides

ABSTRACT Simultaneously achieving high thermal stability and excellent scintillation performance in Mn‐based organic inorganic hybrid metal halide (Mn‐OIMH) scintillators remains a highly challenging task. Through the rational substitution of the monocation by asymmetric dications on the monocationic compound (Br‑BuTPP) 2 MnBr 4 ( 1 ; Br‐BuTPP = bromine‐butyl‐triphenylphosphonium), dicationic Mn‑OIMHs of [ A ‑(BuTPP)]MnBr 4 ( A denotes PMe ( N ‑methylpyrrolidinium) for 2 , Py (pyridinium) for 3 and PPMe ( N ‑ methylpiperidinium) for 4 ) have been synthesized. The structural rigidity of 2 – 4 is enhanced owing to strengthened electrostatic interactions and hydrogen bonding, thereby suppressing non‐radiative transitions. Consequently, they exhibit significantly improved thermal stability and photophysical properties compared to 1 . Notably, 4 represents the first reported synergistic breakthrough in Mn‐OIMH scintillators, simultaneously achieving exceptional anti‐thermal quenching (ATQ) performance with 94% of initial luminescence retained at 450 K ( I 450K = 94%) and an ultrahigh light yield (LY) of 83359 ± 489 ph/MeV which outperforms most of the reported Mn‐OIMH scintillators. A flexible scintillation film, fabricated by embedding 4 in polydimethylsiloxane, further demonstrates exceptional spatial resolution (17.5 lp/mm), significantly outperforming that of commercial CsI:Tl detectors (≈10 lp/mm). This work validates the asymmetric dual‐charge‐center strategy as a robust and generalizable approach for designing thermally stable and high‐performance scintillators.