Faculty of Science

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Browsing Faculty of Science by Author "Cho, Jaeyoung"

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    Rapid and convenient crystallization of quantum dot CsPbBr3 inside a phosphate glass matrix
    (Elsevier, 2022-06-15) Aryal, Pabitra; Kim, HongJoo; Saha, Sudipta; Cho, Jaeyoung; Ntarisa, Amos Vincent; Kothan, Suchart; Kaewkhao, Jakrapong
    Although inorganic halide perovskite quantum dots (QDs) have promising photophysical properties and a wide range of applications, they suffer from some issues such as poor water and thermal stabilities. Here, we developed a simple strategy to embedded CsPbBr3 QDs in a glass matrix by adopting conventional melt-quenching technique. We systematically presented the modified glass melting and quenching technique for the direct crystallization of CsPbBr3 QDs inside a glass matrix. Crystallization of the QDs took place during the cooling of the quenched hot glass melt. The effect of the concentration of Cs2CO3, PbBr2 and NaBr on the formation of CsPbBr3 QDs size was also identified. The glasses containing CsPbBr3-embedded QDs showed photoluminescence emission stability without any alteration in their emission peaks and full-width at half-maximum for at least six months under ambient conditions. Our results provide new insights into rapid and convenient crystallization of QDs inside the protective glass matrix. The technique can be utilized to fabricate several rare earth ions co-doped QDs glasses for various color tunable lighting optical devices application.
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    Synthesis and luminescence studies of Dy3+ doped Li3Sc(BO3)2 polycrystalline powder for warm white light
    (Elsevier, 2022-04-15) Saha, Sudipta; Kim, HongJoo; Khan, Arshad; Cho, Jaeyoung; Kang, Sinchul; Ntarisa, Amos Vincent
    Li3Sc(BO3)2, an orthoborate polycrystalline compound, was synthesised using the solid-state synthesis method as a pure and Dy2O3-doped material. Dy3+ ions were used in various concentrations (from 1 to 6 mol. %). The experimental powder X-ray diffraction data and calculated Rietveld refined data are found to be in good agreement, verifying the effectiveness of the synthesis procedure. The luminescence studies were performed under the excitations of X-ray, proton beam, and UV light. The success of radioluminescence studies verifies the prospects of the Dy3+-doped compound for its application as a radiation scintillator in imaging. The experimental study of cross-relaxation processes confirms the lack of potential evidence of the quenching of the emission peak at 765 nm through the absorption via 6H15/2 → 6F3/2 electronic transition cross-relaxation channel−1. The CIE 1931 colour coordinates and correlated colour temperatures were determined for all doped samples under X-ray, proton beam, and photoluminescence excitations. The obtained combined emission colour appeared in the warm white region, unlike many other Dy3+-doped phosphors that suffer suppression of luminescence through the cross-relaxation process.