A series of K1–2x–2y Ba y Al11O17(KBAO):xEu2+ phosphors are designed to develop a blue phosphor with excellent thermal properties. All of the samples present similar β-Al2O3 structures with P63/mmc space group; the K+ vacancy can exist stably until the Ba2+ concentration exceeds around y = 0.3. KBAO:Eu2+ exhibits strong absorption for near-ultraviolet light and relatively standard blue emission. The mechanisms for excitation and emission spectrum variations have also been studied in detail. Based on the adjustment of K+ vacancy numbers in the defect structure, K0.6Ba0.1Eu0.1Al11O17 exhibits a remarkable quantum yield of around 91.2% and a terrific high-temperature characteristic. The zero-thermal quenching performance mainly results from stabilization of the flowing electron number between Eu2+ 5d levels and K+ defect ε­(0/–1) and ε­(+1/0) levels in the processes of thermal ionization and recombination. A bright fabricated white-light-emitting diode (WLED) gives a color rendering index (CRI) of R a = 87 and a correlated color temperature (CCT) of 4510 K, demonstrating that KBAO:Eu2+ has application potential to provide a blue light component in WLED. In addition, our research is a significant attempt to achieving stable zero-thermal quenching by subjective structure design, which provides a reference value for investigating the excellent new phosphors.

Nowadays liquid crystal displays (LCD) backlighting has become an independent subject of the display field, and gradually formed a research and development hotspot. The narrow-band emitting phosphors which play an...

We have fabricated CsPbBr3 perovskite quantum dots (QDs) in a multi‐component borate glass by melt‐quenching technique. Transmission electron microscopy (TEM) reveals a cubic phase CsPbBr3 crystal for QDs. As the treatment temperature or the treatment time duration increases, the photoluminescence (PL) peak shifts to long wavelength in the range of 510 to 525 nm, and the full width at half‐maximum varies in the range of 24 to 18 nm. The absorption edge shifts to low energy side in the range of 2.54 to 2.41 eV. The different photoluminescence excitation spectra (PLE) reflect the change of microstructure for different samples. The PL peak wavelength and line‐shape are independent of excitation wavelength. These results of spectra show typical exciton emission characteristics. As treatment conditions strengthens, photoluminescence quantum yield (PLQY) first increases and then decreases, having the best PLQY 86.9%. Bi‐exponential fitting curves show that short lifetime τ1 continuously decreases. Long lifetime τ2, weight for long lifetime component, and average lifetime τavg first increase and then decrease. The PLQY values are affected by both τ1 and τ2, which are relative to the crystal quality in the interior and the surface of QDs, respectively. The high PLQY value corresponds to medium treatment condition, which is attributed to a balanced effect of crystal quality in interior and the surface of QDs.

Upconversion (UC) luminescence refers to the conversion of electromagnetic waves from long to short wavelengths through multi-photon processes where the absorption of infrared (IR) photons leads to visible emission, which has attracted a lot of attention on the bioimaging, 3-D color display, printing ink, state-of-the-art lighting, solar cell, fingerprint acquisition, anti-counterfeiting, and so on. 1-7 Particularly, based on the measurement of temperature-dependent UC luminescence intensity of two thermally coupled energy levels of trivalent rare earth (RE 3+) ions, the non-contact optical temperature sensor by using the fluorescence intensity ratio (FIR) technique still keeps a research hotspot in recent years owing to its advantages of fast response, high sensitivity and resolution. 8-13 Under consideration of UC luminescence and temperature sensing properties, the Er 3+ ion with a pair of thermally coupled energy levels (2 H 11/2 and 4 S 3/2) is often regarded as the one of the most important activator ions to obtain strong UC luminescence in visible

Usually, the optical transition properties of trivalent rare earth (RE) ions in transparent hosts can be quantitatively investigated in the framework of Judd-Ofelt theory. A standard and commonly accepted calculation...