title: Vacuum-Referred Binding Energies of Bismuth and Lanthanide Levels in ARE(Si,Ge)O 4 (A = Li, Na; RE = Y, Lu): Toward Designing Charge-Carrier-Trapping Processes for Energy Storage 文章链接: https://pubs.acs.org/doi/10.1021/acs.chemmater.9b04341?fig=tgr1ref=pdf Abstract Developing a feasible design principle for solid-state materials for persistent luminescence and storage phosphors with high charge carrier storage capacity remains a crucial challenge. Here we report a methodology for such rational design via vacuum referred binding energy (VRBE) diagram aided band structure engineering and crystal synthesis optimization. The ARE(Si,Ge)O 4 (A = Li, Na; RE = Y, Lu) crystal system was selected as a model example. Low-temperature (10 K) photoluminescence excitation and emission spectra of bismuth- and lanthanide-doped ARE(Si,Ge)O 4 system were first systematically studied, and the corresponding VRBE schemes were then established. Guided by these VRBE schemes, Bi 3+ afterglow and storage phosphor properties were explored in NaLu 1– x Y x GeO 4 . By combining Bi 3+ with Bi 3+ itself or Eu 3+ , Bi 3+ appears to act as a deep hole-trapping center, while Bi 3+ and Eu 3+ act as less-deep electron traps. Trap depth tunable afterglow and storage were realized in NaLu 1– x Y x GeO 4 :0.01Bi 3+ and NaLu 1– x Y x GeO 4 :0.01Bi 3+ ,0.001Eu 3+ by adjusting x , leading to conduction band engineering. More than 28 h of persistent luminescence of Bi 3+ was measurable in NaYGeO 4 :0.01Bi 3+ due to electron release from Bi 2+ and recombination with a hole at Bi 4+ . The charge carrier storage capacity in NaYGeO 4 :0.01Bi 3+ was discovered to increase ～7 times via optimizing synthesis condition at 1200 °C during 24 h. The thermoluminescence (TL) intensity of the optimized NaYGeO 4 :0.001Bi 3+ and NaYGeO 4 :0.01Bi 3+ ,0.001Eu 3+ is ～3, and ～7 times higher than the TL of the state-of-the-art X-ray storage phosphor BaFBr(I):Eu. Proof-of-concept color tuning for anti-counterfeiting application was demonstrated by combining the discovered and optimized NaYGeO 4 :0.01Bi 3+ afterglow phosphor with perovskite CsPbBr 3 and CdSe quantum dots. Information storage application was demonstrated by UV-light- or X-ray-charged NaYGeO 4 :0.01Bi 3+ ,0.001Eu 3+ phosphor dispersed in a silicone gel imaging film. This work not only reports excellent storage phosphors but more importantly provides a design principle that can initiate more exploration of afterglow and storage phosphors in a designed way through combining VRBE-scheme-guided band structure engineering and crystal synthesis optimization.
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