Vacuum-Referred Binding Energies of Bismuth and Lanthanide Levels in LiTaO₃ Perovskite: Toward Designing Energy Storage Phosphor for Anti-Counterfeiting, X-Ray Imaging, and Mechanoluminescence

Discovering UV-light or X-ray charged afterglow and storage phosphors with high charge carrier storage capacity remains challenging. Herein, a method is proposed by combining vacuum referred binding energy (VRBE) diagram construction and optimization of dopants’ concentration and compound synthesis. The refined chemical shift model, optical spectroscopy, and thermoluminescence will be combined to construct the VRBE diagram of LiTaO₃ with the lanthanide and bismuth charge transition levels. Based on the constructed VRBE diagram of LiTaO₃, Bi³⁺, and/or Ln³⁺ (Ln = Tb or Pr) doped LiTaO₃ will be studied. By combining Bi³⁺ with Tb³⁺, Pr³⁺, or Bi³⁺ itself, Bi³⁺ emerges to act as a ≈0.62 eV deep electron trap, while Tb³⁺, Pr³⁺, or Bi³⁺ acts as about 1.5 eV deep hole capturing and recombination centres. The VRBE in the Bi^{2+ 2}P_1/2 ground state will be derived by thermoluminescence study. Proof-of-concept X-ray imaging, compression force distribution monitoring, and color-tailoring for anti-counterfeiting will be demonstrated by using the developed Bi³⁺ and/or Ln³⁺ doped LiTaO₃. This work promotes the understanding of trap level locations and on the trapping and release processes of charge carriers in Bi³⁺ and/or lanthanides doped inorganic compounds for rational design of new afterglow and storage phosphors.