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Upconversion luminescence properties of Y2O3: Yb3+/Er3+/Tm3+ nanocrystal doped PMMA nanocomposites
摘要： Y2O3 nanocrystals triply doped with Yb3+, Er3+, Tm3+ ions were synthesized via alginic acid-assisted gelation using thermal decomposition method and annealed at 800 °C for 24 h. Nanopowders were embedded into PMMA matrix via free-radical polymerization in an ultrasonic bath. X-ray diffraction and transmission electron microscopy measurements have shown that the crystal grain sizes decreased significantly with the narrow size distributions of the nanocrystals in PMMA matrix. A diode laser at 975 nm was used to measure the upconversion luminescence of the annealed nanopowders and those embedded in PMMA between the 400–850 nm wavelength region. The Er3+ concentration and the excitation power density dependencies of the relative intensities for red, green and blue upconversion luminescence in the nanopowder and PMMA nanocomposites are found to be different. The measured CIE-1931 color coordinates of the upconversion luminescence in PMMA nanocomposites show appreciable color stability under different excitation power densities, which is required for potential applications in the field of photonics.
关键词： Color Tunable Emission,Upconversion Luminescence,Polymer nanocomposites,Color Stability,Polymethyl methacrylate (PMMA)
更新于2025-09-23 15:21:21
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High-performance white organic light-emitting diodes with doping-free device architecture based on the exciton adjusting interfacial exciplex
摘要： White organic light-emitting diodes (WOLEDs) with doping-free device architecture have aroused more attention due to their attractive merits such as simplified fabrication procedures and reduced costs. However, the electroluminescence performance of that is still manifestly unsatisfactory and needs to be further improved. Here, high-performance doping-free two-color and three-color WOLEDs with the accurate manipulation of excitons have been successfully fabricated by optimizing the interfacial exciplex. As a result, two-color WOLEDs exhibit the controllable electroluminescence spectra with a wide correlated color temperature (CCT) spanning from 2878 to 9895 K at the voltage of 4 V, as well as the maximum forward-viewing power and current efficiencies of 83.2 lm W?1 and 63.3 cd A?1, respectively. The three-color WOLED not only realizes the maximum efficiencies of 50.1 lm W?1 and 44.7 cd A?1, but also exhibits superior color stability with a color rendering index of 86, a CCT of 2679 K, and a Commission International de I’Eclairage coordinates of (0.49, 0.46) at the voltage of 5 V. Such surprising efficiencies obtained in our WOLEDs indicate that the reasonable application of interfacial exciplex should be a helpful way to develop high-performance and low cost WOLEDs with a simple technology.
关键词： high-performance,color stability,White organic light-emitting diodes,doping-free,interfacial exciplex
更新于2025-09-23 15:19:57
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Bright and Color-Stable Blue-Light-Emitting Diodes based on Three-Dimensional Perovskite Polycrystalline Films via Morphology and Interface Engineering
摘要： Substantial progress has been achieved in red and green perovskite light-emitting diodes (PeLEDs). However, blue PeLEDs are still inferior in light-emitting efficiency and luminance compared with their green and red counterparts. Herein efficient blue PeLEDs simultaneously achieving high luminance and high color stability are fabricated based on the polycrystalline perovskites with a 3D Rb?Cs alloyed scaffold. The synergistic manipulation of an isopropanol antisolvent treatment and the PEDOT:PSS/blue perovskite interface modification with RbCl effectively improve the photoluminescence properties of the resultant blue polycrystalline 3D perovskite films and the final electroluminescence performance of the blue PeLEDs. The optimized blue PeLEDs show a maximum external quantum efficiency of 1.66% with an emission peak at 484 nm and a full width at half-maximum of 18 nm as well as CIE coordinates of (0.08, 0.21). Moreover, the optimized blue PeLEDs not only show superior color stability under various luminances but also achieve high luminances. The obtained maximum luminance of 9243 cd m?2 is one of the highest values among the efficient and color-stable blue PeLEDs.
关键词： blue PeLEDs,perovskite light-emitting diodes,Rb?Cs alloyed scaffold,color stability,high luminance
更新于2025-09-19 17:13:59