Yong Liu,Zhi Zhou,Lin Huang,Mikhail G. Brik,Shuaichen Si,Litian Lin,Tongtong Xuan,Hongbin Liang,Jianbei Qiu,Jing Wang
Narrow-band red-emitting fluoride phosphors for wide color gamut LED backlights have evoked considerable attention, due to their fascinating optical properties. Unfortunately, poor moisture resistance often restricts their further applications in optoelectronics. Herein we developed a Cs2SiF6:Mn4+ red phosphor using a low-temperature co-precipitation method and passivating it by using H2O2. The phosphor shows a very high external quantum efficiency (EQE) of ∼85% and exhibits excellent moisture stability retaining 74% of its emission intensity after being exposed to high temperature (85 °C) and high humidity (85%) (HTHH) for 168 h. Finally, the high brightness white LED devices combined with the passivated Cs2SiF6:Mn4+ exhibit high luminous efficacy of 133 lm W−1 and wide color gamut (∼84.7% NTSC). The results demonstrate that the passivated Cs2SiF6:Mn4+ with high EQE and excellent moisture-resistance is promising as a narrow-band red emitting phosphor for wide color gamut LED backlights.
Lead halide perovskites have received extensive attention due to their excellent photoelectric and photonic properties. However, low stability is an obstacle to material production and optoelectronic applications. In this research study, CsPbBr3/Cs2SiF6:Mn4+ rivet nanostructured perovskites coated with ZnS and self-passivation layers have been synthesized. The rivet nanostructured perovskites are applied in tunable white light-emitting diode (WLED) devices and tunable flexible white electroluminescent (EL) devices. The red and green dual-wavelength tunable luminescence in the rivet nanostructured perovskites has been obtained via Cs ion sharing. Upon the addition of ZnS and a self-passivation aluminum layer coating on the surface of the rivet perovskites, the photoluminescence (PL) intensity and the stability increased by 588.7 and 323.6%, respectively. In addition, a series of spectrally tunable WLED devices with an InGaN blue LED chip and flexible white EL devices is fabricated using the CsPbBr3/Cs2SiF6:Mn4+/2ZnS/Al rivet nanostructured perovskites. The tunable WLED devices can produce standard white light and cold and warm white light. The tunable EL devices produce luminescence even at 60° bending. By studying the temperature-dependent PL spectra of CsPbBr3/Cs2SiF6:Mn4+/nZnS/Al rivet nanostructured perovskites, the energy transfer mechanism at cryogenic and room temperatures is analyzed. At the same time, the protection principle of the self-passivation coating on the CsPbBr3/Cs2SiF6:Mn4+ rivet nanostructured perovskites is discussed.
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