Nowadays, high-quality phosphor-converted white light-emitting diodes (pc-WLEDs) ought to include cyan-emitting phosphors allowing for full-spectrum light similar to sunlight. Herein, we report a garnet-structured Ce 3+ -doped SrLu 2 Ga 1.5 Al 2.5 SiO 12 (SLGASO) phosphor that significantly compensates for the absence of cyan light, known as the “cyan cavity”. The SLGASO host crystallizes into a cubic structure with the I a 3 ¯ d space group. The cell parameters were determined using Rietveld refinement. Under 430 nm blue excitation, SLGASO:Ce 3+ emits intense cyan-green light in the 450–700 nm wavelength range. The representative SLGASO:0.07Ce 3+ phosphor has an internal quantum efficiency (IQE) of 95.4% and excellent thermal stability, remaining 92.7% of its initial emission intensity at 152 °C. After 155 d of immersion in water, the luminous intensity of SLGASO:0.07Ce 3+ remains constant, confirming its waterproofness. Furthermore, a pc-WLED device with luminous efficiency (LE) of 101.58 lm/W, color rendering index ( Ra ) of 91, correlated color temperature (CCT) of 4536 K, and Commission Internationale de L'Eclairage (CIE) chromaticity coordinates of (0.3555, 0.3390) was fabricated by combining as-prepared cyan-green-emitting SLGASO:0.07Ce 3+ , yellow-emitting Y 3 Al 5 O 12 :Ce 3+ (YAG:Ce 3+ ), and red-emitting (Ca,Sr)AlSiN 3 :Eu 2+ phosphors, as well as a 450 nm blue chip. These findings indicate that SLGASO:0.07Ce 3+ phosphor can bridge the cyan gap and improve the performance of as-fabricated full-visible-spectrum WLEDs.
Quasi-two-dimensional (quasi-2D) perovskite light-emitting diodes (PeLEDs) are considered as one of the most potential candidates in electroluminescence territory owing to their unique quantum confinement effect and excellent thermal stability of the light. Nevertheless, heterogeneous energy domain distribution leads to severe non-radiative recombination in the process of energy transfer, which enormously hinders the performance and application of PeLEDs. Herein, an ambipolar amino acid, 5-aminovaleric acid (5AVA), is demonstrated to be able to coordinate lead and halides simultaneously with its carboxyl and amidogen groups. The coordinated ambipolar molecule not only reconstitutes energy domains of perovskites but also minimizes the interfacial defects of PeLEDs. Accordingly, the presence of 5AVA in perovskite precursors leads to dramatic suppression of the n = 1 and n = 2 phases and accelerates energy transfer from wide bandgap domains to narrow bandgap ones. As a result, maximum external quantum efficiency (EQE) of 19.3% (18.20% ± 1.10%) is achieved in quasi-2D green PeLEDs with current efficiency of 61.7 cd A −1 .
Perovskite has shown attractive optoelectronic performances and is a potential material in lighting, anti-counterfeiting, sensor, and other optoelectronic devices. Recently, spin-coating has been widely used in fabricating high-performance perovskite films, but it is difficult to process and apply in practice. In this paper, the CsPbBr 3 /Cs 4 PbBr 6 composite perovskite quantum dots with photoluminescence quantum yield of 36% and high storage stability were prepared by using room temperature ligand-assisted precipitation method and controlling the proportion of CsBr/PbBr 2 . In addition, the composite perovskite was ground and dispersed in the inks system. After adjusting the composition and ratio of the resin components, the inks were suitable for screen printing with a viscosity of 2439 mPa•s, an initial dryness of 25 mm/30 s, and a thorough dryness of 100 s/100 μm. By printing, the perovskite films exhibited high coverage, strong green emission, and outstanding fluorescence recovery ability after exposure to water. Screen printing perovskite inks have the characteristic of being patternable, which provides a solution for preparing a perovskite film in the application.
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