Lin Zhang,Fei Ma,Qingmei Guan,Chang Wang,Cuibing Bai,Liangquan Sheng
The flaky Bi 3+ sensitized Gd 2 O 2 SO 4 : Eu 3+ compounds were prepared from the sodium dodecyl sulfate intercalated layered rare-earth hydroxide by calcination at 800 °C. The precursor Gd (1.9-X) Eu 0.1 Bi X (OH) 5 NO 3 ·1.5H 2 O was fabricated by methanol-solvothermal reaction at 150 °C for 12h. XRD and TEM analyses demonstrated that the precursor LGdH were formed of crystallites with a uniform crystallographic orientation. After the anion DS − intercalated, the interlayer space of LGdH increased, but the layer structure did not change. Their single-crystal nature and sheet-like morphology were reserved after calcination, The excitation spectrum monitored by 612 nm featured a broad band at 332 nm which could be ascribed to the 6s 2 -6s6p transition of Bi 3+ , and, accordingly the flaky Gd 2 O 2 SO 4 :Eu 3+ ,Bi 3+ exhibited greatly enhanced characteristic red emission of Eu 3+ . The PL properties of the Gd 2 O 2 SO 4 :Eu 3+ ,Bi 3+ samples were measured at different concentrations of Bi 3+ and fixed Eu 3+ concentration 5 at%, and the highest PL quantum yield was 20.58% of Gd 2 O 2 SO 4 :Eu 3+ ,Bi 3+ at a Bi 3+ concentration of 4 at%.
Phosphor-converted light emitting diodes (pc-LEDs) are essential for current lighting and display areas because of their unique properties of being uncomplicated, durable and economical. In previous studies, Pr 3+ doped red-emitting phosphors have attracted enormous research interest due to their high color purity. However, their photoluminescence excitation (PLE) spectra are always hard to be combined with LED chips. This mismatch is a great obstacle to achieve Pr 3+ phosphors utilizing in LED devices. Here, to circumvent this issue, Pr 3+ -doped Ca 3 MgTiGe 3 O 12 (CMTG) red-emitting phosphor was optimized with PLE band shifting from 330 nm to 360 nm after tuning with Bi 3+ co-doping based on the structure and phosphorescence properties. The chip-matched excitation makes it a good candidate for white LEDs (wLEDs) fabrication to improve the output quality of device. Meanwhile, the high color purity of 93.02 % was obtained, which is conducive to widening the color gamut of backlight display applications. The photoluminescence (PL) spectra, fluorescence lifetime, and X-ray photoelectron spectroscopy (XPS) analysis were employed and discussed in detail to explain the role of Bi 3+ played in the system. Finally, wLEDs were fabricated with CMTG:Pr 3+ , Bi 3+ , showing a high color rendering index (Ra) of 94.4. And the color gamut covers ∼80 % of the National Television System Committee (NTSC) standard, suggesting great potential for applications of wLEDs and backlight display.
Self-activated near-infrared (NIR) phosphors have garnered increasing attention in advanced light sources and biomedical applications owing to their simplified synthesis, cost-efficiency, non-toxicity, and especially the absence of extrinsic activator ions. However, developing efficient and thermally stable self-activated NIR phosphors remains a significant challenge for practical applications. Herein, a NIR phosphor Ca 0 · 95 LaMgSbO 6 (C 0.95 LMSO) (λex = 335 nm, λem = 710 nm) is synthesized employing a non-stoichiometric strategy, where interstitial oxygen (Oᵢ) defects are identified as the primary origin for the self-activated NIR luminescence through synergistic experimental and theoretical analyses. The controlled Ca 2+ deficiency promotes the generation of more Oᵢ defects, thereby enhancing the intensity of Oᵢ defect-induced near-infrared luminescence. Furthermore, the introduction of Bi 3+ sensitizers enables efficient energy transfer pathways, the optimized phosphor leading to exceptional photoluminescence quantum yield (68.1 %) and thermal stability (67.2 % intensity retention at 420 K). A fabricated NIR pc-LED based on Ca 0 · 95 LaMgSbO 6 :0.5 %Bi 3+ (C 0.95 LMSO: Bi 3+ ) phosphor exhibit promising performance in night vision and biomedical imaging applications. This study elucidates a defect-engineering paradigm grounded in oxygen interstitial defects, presenting a new research avenue for the development of high-performance self-activated NIR materials.
危险品化学品经营许可证（带存储）