Green Ethanol-Based Synthesis of Lead-Free Hybrid Organic Manganese(II) Halide Nanoparticles for Efficient and Stable β-ray Scintillators

High fabrication costs and low luminescence efficiency limit the practical application of β-ray scintillators in isotope batteries. This study reports a type of green-synthesized lead-free manganese halide (TPP2MnX4 (X = Br, Cl)) nanoparticle for β scintillating applications. It is found that the TPP2MnBr4 nanoparticles exhibit a higher photoluminescence quantum yield (PLQY, 71.87%) than that of TPP2MnCl4 (23.50%) under 360 nm ultraviolet excitation. Furthermore, the anti-thermal quenching effect at 233 to 300 K is observed from TPP2MnX4 for the first time, which explains the relatively high room-temperature PLQY. The TPP2MnBr4 nanoparticles exhibit excellent β-ray scintillation performance, with a radio luminescent intensity of 13.23k at 400 Gy/s (equal to 94.5% of commercial ZnS/Cu). It retains 70% of its initial luminescent intensity after a cumulative dose of 240 kGy and 54% at 100 °C, indicating good radiation and thermal stability. The enhanced β-ray scintillating properties may be attributed to a weaker electron–phonon coupling, resulting from the Br coordination. Additionally, the encapsulation strategies toward TPP2MnBr4 nanoparticles by using PDMS substrates and aerosol jet printing are demonstrated. This work highlights a green synthesis strategy, promising the radiant luminescence performance of TPP2MnX4 and the mechanism of the unique scintillating properties.