Highly Efficient Organic Metal Halide Hybrid Scintillator

Scintillators, which could convert high energy ionizing radiations to visible light photons, have recently seen surges of applications in various areas, ranging from nuclear substance monitoring to medical imaging and many industrial control systems. While a variety of materials, including inorganic single crystals, organic molecules, and plastics, have been developed for radiation scintillation, all of them have their own drawbacks and there is not yet a single material that possesses a combination of high radiation absorption, high light yield, fast responsivity with short decay lifetimes, and low cost of mass production.<br/>In this talk, I will introduce a new design concept for the development of organic-inorganic hybrid scintillation materials that could be facilely prepared via low-temperature processes and exhibit high light yields with short decay lifetimes. For the proof of concept, a zero-dimensional (0D) organic metal halide (4-(4-(diphenylamino) phenyl)-1-(propyl)-pyrindin-1ium zinc bromide (TPA-P)₂ZnBr₄) exhibiting yellowish-green emission peaked at around 550 nm has been designed, synthesized, and fully characterized. Unlike previously reported organic metal halide hybrids with metal halides as emitter, (TPA-P)₂ZnBr₄ has high Z metal halides acting as X-ray sensitizer and aggregation-induced emission (AIE) organic cations as emitter. As a result, dramatically enhanced X-ray scintillation of TPA-P⁺is achieved via sensitization by ZnBr₄^2-. A light yield of 36,200 Photons/MeV is achieved for this 0D hybrid material, which is significantly higher than that of anthracene (~15,000 Photons/MeV) and comparable to those of inorganic scintillators, while the photoluminescence and radioluminescence decay lifetimes of 3.56 ns and 9.96 ns respectively are similar to those of pure organic scintillators. Moreover, the high light yield to decay time ratio of 3,634 Photons/MeV×ns and low detection limit of 21.3 nGy_airs^-1 are among the best values achieved to date for all kinds of scintillation materials. Our work provides a new strategy to achieve molecular sensitization in ionically bonded organic-inorganic hybrid systems and expands the utility and tunability of functional organic molecules in these hybrid systems for useful optoelectronic applications.