Liquid Scintillators Loaded with up to 40 Weight Percent Cesium Lead Bromide Quantum Dots for Gamma Scintillation

Cesium lead bromide quantum dot (CsPbBr3 QD) is emerging as a promising luminescent material for gamma ray detection. However, its intensive self-absorption traps the luminescent photons generated and diminishes the scintillation light yield. The self-absorption is magnified at high CsPbBr3 QD loading and large scintillator volume, which are required to effectively attenuate gamma photons. We report a liquid scintillator loaded with up to 40 wt % of CsPbBr3 QDs. Pyrromethene 580 (PM-580), a fluorescent dye, was co-dissolved in the solution as a fluorescence resonance energy-transfer acceptor to overcome the self-absorption of the QDs. The rapid energy transfer from the QDs to PM-580 also accelerates the scintillation decay kinetics. The scintillation light yield of the liquid containing 20 wt % QDs and 0.75 wt % PM-580 was 8800 photons/MeV. The decay lifetime is 24.3 ns, faster than most inorganic crystal scintillators. The light yield was 7300 photons/MeV at 40 wt % QD loading. Gamma pulse spectroscopy of the 40 wt % QD liquid produced the 662 keV gamma photopeak with a 27% energy resolution, demonstrating the potential of the CsPbBr3 QD loaded organic scintillators for spectroscopic gamma detection.