White emission metal halides for flexible and transparent x-ray scintillators

Flat-panel x-ray scintillators with a high spatial resolution at a low radiation dose rate are desirable for efficient imaging applications in medical diagnostics, security inspection, and nondestructive inspection. To promote the progress of x-ray imaging technologies, it is of great interest to explore transparent scintillators with reduced light scattering, high light yields, and uniform radioluminescence. Herein, we design and prepare a novel lead-free (C 12 H 28 N) 2 Cu 2 I 4 metal halide featuring a high luminescent efficiency and white emission benefiting from the double self-trapped exciton mechanism, which enable to not only match the response of semiconductor-based sensors but also enhance light yields and decrease exposed doses to objects. Furthermore, transparent, and flexible scintillators with large areas of 20.25 cm 2 demonstrate an outstanding scintillation performance including a high spatial resolution of 19.8 lp mm −1 and an ultralow detection limit of 28.39 nGy air s −1 , which are ∼4 times higher and 194 times lower than typical values for medical imaging, respectively. This work provides not only a new route to explore promising alternatives with broadband emission but also a novel opportunity to develop flexible x-ray imaging technology.