Litcius/Paper detail

Vacuum-Referred Binding Energies of Bismuth and Lanthanide Levels in ARE(Si,Ge)O<sub>4</sub> (A = Li, Na; RE = Y, Lu): Toward Designing Charge-Carrier-Trapping Processes for Energy Storage

Tianshuai Lyu, P. Dorenbos

2020Chemistry of Materials74 citationsDOIOpen Access PDF

Abstract

&lt;p&gt;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&lt;sub&gt;4&lt;/sub&gt; (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&lt;sub&gt;4&lt;/sub&gt; system were first systematically studied, and the corresponding VRBE schemes were then established. Guided by these VRBE schemes, Bi&lt;sup&gt;3+&lt;/sup&gt; afterglow and storage phosphor properties were explored in NaLu&lt;sub&gt;1-x&lt;/sub&gt;Y&lt;sub&gt;x&lt;/sub&gt;GeO&lt;sub&gt;4&lt;/sub&gt;. By combining Bi&lt;sup&gt;3+&lt;/sup&gt; with Bi&lt;sup&gt;3+&lt;/sup&gt; itself or Eu&lt;sup&gt;3+&lt;/sup&gt;, Bi&lt;sup&gt;3+&lt;/sup&gt; appears to act as a deep hole-trapping center, while Bi&lt;sup&gt;3+&lt;/sup&gt; and Eu&lt;sup&gt;3+&lt;/sup&gt; act as less-deep electron traps. Trap depth tunable afterglow and storage were realized in NaLu&lt;sub&gt;1-x&lt;/sub&gt;Y&lt;sub&gt;x&lt;/sub&gt;GeO&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt; and NaLu&lt;sub&gt;1-x&lt;/sub&gt;Y&lt;sub&gt;x&lt;/sub&gt;GeO&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt;,0.001Eu&lt;sup&gt;3+&lt;/sup&gt; by adjusting x, leading to conduction band engineering. More than 28 h of persistent luminescence of Bi&lt;sup&gt;3+&lt;/sup&gt; was measurable in NaYGeO&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt; due to electron release from Bi&lt;sup&gt;2+&lt;/sup&gt; and recombination with a hole at Bi&lt;sup&gt;4+&lt;/sup&gt;. The charge carrier storage capacity in NaYGeO&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt; was discovered to increase ∼7 times via optimizing synthesis condition at 1200 °C during 24 h. The thermoluminescence (TL) intensity of the optimized NaYGeO&lt;sub&gt;4&lt;/sub&gt;:0.001Bi&lt;sup&gt;3+&lt;/sup&gt; and NaYGeO&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt;,0.001Eu&lt;sup&gt;3+&lt;/sup&gt; 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&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt; afterglow phosphor with perovskite CsPbBr&lt;sub&gt;3&lt;/sub&gt; and CdSe quantum dots. Information storage application was demonstrated by UV-light- or X-ray-charged NaYGeO&lt;sub&gt;4&lt;/sub&gt;:0.01Bi&lt;sup&gt;3+&lt;/sup&gt;,0.001Eu&lt;sup&gt;3+&lt;/sup&gt; 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.&lt;/p&gt;

Topics & Concepts

PhosphorLuminescencePhotoluminescenceThermoluminescenceAfterglowMaterials scienceBismuthLanthanideCharge carrierDopingAnalytical Chemistry (journal)OptoelectronicsChemistryIonPhysicsMetallurgyGamma-ray burstAstronomyOrganic chemistryChromatographyLuminescence Properties of Advanced MaterialsRadiation Detection and Scintillator TechnologiesPerovskite Materials and Applications