Blue-emitting long-persistent luminescence phosphor Pb2+-doped CsCdCl3

In our traditional impressions, the emission spectra of Pb²⁺ ions usually fall predominantly within the UV region. In this work, we find when coordinated with haloid Cl⁻ ions in CsCdCl₃, the Pb²⁺ ions could demonstrate bright blue emission from 350 to 500 nm with maximum peaking at about 412 nm under the excitation of 250–320 nm light. This emission can be assigned to ³P₁ → ¹S₀ transition of Pb²⁺ ions. More interestingly, this all-inorganic metal halide compound CsCdCl₃:Pb²⁺ exhibits a long persistent luminescence (LPL) lasting 1050 s, endowed with application potential in the information storage and function of analysis and detection. The LPL mechanism of Pb²⁺ in CsCdCl₃ has been studied by thermoluminescence (TL) measurements and the First-principle calculation, which dominate that the 6p levels of Pb²⁺ are just below the conduction band by about 0.6 eV. The excited electrons can travel across these 6p levels and the electron traps through the conduction band thermally, delaying the emission temporarily and producing the afterglow finally. Our finding in this work proves the potential of Pb²⁺ activated phosphors in visible region and provides a unique approach to construct Pb²⁺ doped LPL phosphors.