Currently, metal
halide perovskite nanocrystals have been extensively
explored due to their unique optoelectronic properties and wide application
prospects. In the present work, a facile grinding method is developed
to prepare whole-family APbX3 (A = MA, FA, and Cs; X =
Cl, Br, and I) perovskite nanocrystals. This strategy alleviates the
harsh synthesis conditions of precursor dissolution, atmosphere protection,
and high temperature. Impressively, the as-prepared perovskite nanocrystals
are evidenced to have halogen-rich surfaces and yield visible full-spectral
emissions with maximal photoluminescence quantum yield up to 92% and
excellent stability. Additionally, the grinding method can be extended
to synthesize widely concerned Mn2+-doped CsPbCl3 nanocrystals with dual-modal emissions of both excitons and dopants.
As a proof-of-concept experiment, the present perovskite nanocrystals
are demonstrated to be applicable as blue/green/red color converters
in UV-excitable white-light-emitting diodes.
CsPbX3 (X = Br, I) QD embedded glasses are fabricated via a glass crystallization strategy, exhibiting tunable luminescence and superior thermal stability.
As a novel type of promising materials, metal halide perovskites are a rising star in the field of optoelectronics. On this basis, a new frontier of zero-dimensional perovskite-related Cs4PbBr6 with bright green emission and high stability has attracted an enormous amount of attention, even though its photoluminescence still requires to clarification. Herein, the controllable phase transformation between three-dimensional CsPbBr3 and zero-dimensional Cs4PbBr6 is easily achieved in a facile ligand-assisted supersaturated recrystallization synthesis procedure via tuning the amount of surfactants, and their unique optical properties are investigated and compared in detail. Both Cs4PbBr6 and CsPbBr3 produce remarkably intense green luminescence with quantum yields up to 45% and 80%, respectively; however, significantly different emitting behaviors are observed. The fluorescence lifetime of Cs4PbBr6 is much longer than that of CsPbBr3, and photo-blinking is easily detected in the Cs4PbBr6 product, proving that the zero-dimensional Cs4PbBr6 is indeed a highly luminescent perovskite-related material. Additionally, for the first time, tunable emissions over the visible-light spectral region are demonstrated to be achievable via halogen composition modulations in the Cs4PbX6 (X = Cl, Br, I) samples. Our study brings a simple method for the phase control of CsPbBr3/Cs4PbBr6 and demonstrates the intrinsic luminescence nature of the zero-dimensional perovskite-related Cs4PbX6 products.
Owing to the conventional phosphor‐converted white LEDs (pc‐WLEDs) generally suffer from blue‐green cavity, thus, developing an appropriate phosphors covering both the blue and green regions in their emission spectra are very urgent. Herein, a novel Sc silicate phosphor, KBaScSi2O7:Eu2+ (KBSS:Eu2+), has been successfully designed and prepared via a solid‐state reaction. The crystal structure, luminescent properties, thermal quenching, quantum efficiency as well as its application in UV‐pumped WLEDs have been investigated systematically. The KBSS:Eu2+ phosphor exhibits a strong and broad excitation band ranging from 290 to 450 nm, and gives a sufficient cyan emission of 488 nm with a full‐width half‐maximum (FWHM) of 70 nm, which filled the blue‐green cavity. Importantly, the optimized KBSS:Eu2+ phosphor possesses an ultrahigh quantum efficiency (QE) up to 91.3% and an excellent thermal stability retaining 90% at 423 K with respect to that measured at room temperature. Finally, the as‐fabricated UV‐based WLEDs device, with only coupled the mixture of KBSS:Eu2+ cyan phosphor and CaAlSiN3:Eu2+ red ones to a commercial 365nm UV chip, exhibits a satisfactory color‐rendering index (Ra = 88.6), correlated color temperature (CCT = 3770K), and luminous efficiency (LE = 21 lm/W).
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