Molecular Sensitization Enabled High Performance Organic Metal Halide Hybrid Scintillator

Abstract

Scintillators, one of the essential components in medical imaging and security checking devices, rely heavily on rare-earth-containing inorganic materials. Here, a new type of organic-inorganic hybrid scintillators containing earth abundant elements that can be prepared via low-temperature processes is reported. With room temperature co-crystallization of an aggregation-induced emission (AIE) organic halide, 4-(4-(diphenylamino) phenyl)-1-(propyl)-pyrindin-1ium bromide (TPA-PBr), and a metal halide, zinc bromide (ZnBr₂ ), a zero-dimensional (0D) organic metal halide hybrid (TPA-P)₂ ZnBr₄ with a yellowish-green emission peaked at 550 nm has been developed. In this hybrid material, dramatically enhanced X-ray scintillation of TPA-P⁺ is achieved via the sensitization by ZnBr₄ ^2- . The absolute light yield (14,700 ± 800 Photons/MeV) of (TPA-P)₂ ZnBr₄ is found to be higher than that of anthracene (≈13,500 Photons/MeV), a well-known organic scintillator, while its X-ray absorption is comparable to those of inorganic scintillators. With TPA-P⁺ as an emitting center, short photoluminescence and radioluminescence decay lifetimes of 3.56 and 9.96 ns have been achieved. Taking the advantages of high X-ray absorption of metal halides and efficient radioluminescence with short decay lifetimes of organic cations, the material design paves a new pathway to address the issues of low X-ray absorption of organic scintillators and long decay lifetimes of inorganic scintillators simultaneously.

Keywords: 0D structures; aggregation-induced emission; molecular sensitization; organic metal halide hybrids; scintillators.