New scintillator film with benign grain boundaries developed for high-resolution, fast X-ray imaging

A research team led by Prof. Wu Yuntao from the Shanghai Institute of Ceramics of the Chinese Academy of Sciences, together with collaborators from Huazhong University of Science and Technology, has developed a new type of inorganic scintillator for high-resolution, fast X-ray imaging. The study was published in Science Advances.

Scintillators are essential in X-ray detectors for small spot detection and high-speed imaging. Columnar structured scintillator films, such as CsI:Tl, enjoy low scattering and inter-pixel crosstalk and have demonstrated their intrinsic advantages in high-resolution and high-pixel fill factor for X-ray flat panel detectors. However, the afterglow effect, which causes residual shadow and blurred images, remains a serious challenge for scintillator films.

In this study, the researchers developed a one-dimensional (1D) Cs₅Cu₃Cl₆I₂ scintillator, in which the carriers are mostly confined within the 1D chains, whose atoms are connected by strong covalent bonds. The 1D Cs₅Cu₃Cl₆I₂ films tend to grow into columnar structures, thermodynamically driven by the faster growth rate along the chains.

Crucially, these films preserve chain integrity at grain boundaries, eliminating detrimental dangling bonds and reducing nonradiative recombination losses and afterglow, thus making them very suitable for scintillator films used in high-resolution and fast imaging.

The rationally designed 1D scintillator Cs₅Cu₃Cl₆I₂ exhibits the long-sought combination of high scintillation yield (1.2 times that of CsI:Tl), low afterglow (0.1% at 10 ms), columnar growth capability, low toxicity, and good stability.

According to the researchers, the Cs₅Cu₃Cl₆I₂ X-ray imager achieved high spatial resolution and excellent detective quantum efficiency, surpassing almost all reported scintillators.

In addition, it has high stability against humidity and continuous irradiation, and its component elements are inexpensive, nontoxic and nonradioactive.

This new material represents a significant breakthrough in the performance and cost of scintillators, opening up new possibilities for fast, high resolution X-ray imaging applications.