Spectrally Tunable Lead-Free Perovskite Rb 2 ZrCl 6 :Te for Information Encryption and X-ray Imaging.

A series of lead-free Rb 2 ZrCl 6 : x Te 4+ ( x = 0%, 0.1%, 0.5%, 1.0%, 2.0%, 3.0%, 5.0%, 10.0%) perovskite materials were synthesized through a hydrothermal method in this work. The substitution of Te 4+ for Zr in Rb 2 ZrCl 6 was investigated to examine the effect of Te 4+ doping on the spectral properties of Rb 2 ZrCl 6 and its potential applications. The incorporation of Te 4+ induced yellow emission of triplet self-trapped emission (STE). Different luminescence wavelengths were regulated by Te 4+ concentration and excitation wavelength, and under a low concentration of Te 4+ doping ( x ≤ 0.1%), different types of host STE emission and Te 4+ triplet state emission could be achieved through various excitation energies. These luminescent properties made it suitable for applications in information encryption. When Te 4+ was doped at high concentrations ( x ≥ 1%), yellow triplet state emission of Te 4+ predominated, resulting in intense yellow emission, which stemmed from strong exciton binding energy and intense electron-phonon coupling. In addition, a Rb 2 ZrCl 6 :2%Te 4+ @RTV scintillating film was fabricated and a spatial resolution of 3.7 lp/mm was achieved, demonstrating the potential applications of Rb 2 ZrCl 6 : x Te 4+ in nondestructive detection and bioimaging.