Lead halide perovskites (LHP) have been intensively studied over the past years due to their attractive optical electronic and optoelectronic properties, including narrow band emission covering whole ...visible region, defect tolerance, and near-unity luminescence quantum yield, which makes them to be promising materials for next generation lighting and display. However, the poor stability of LHP remains the key obstacle restricting their practical applications. This review summarizes the factors which influences the stability of the structure and luminescence properties of LHP, such as the light, heat, humidity and gases. Furthermore, the recent strategies for improving the stability are highlighted at the current state of the art. On the basis of the function mechanism, these methods can be classified into four types: compositional engineering, waterproof materials encapsulation, embedded in heterogeneous crystals, and super-hydrophobic structure, which will be as a guide to overcome the limitations of LHP and impel the development of their practical application.
Display omitted
•The lead halide perovskites nanocrystals are reviewed from aspect of stability.•The factors that influences the stability of the perovskites nanocrystals are summarized.•The methods for improving the stability of the perovskites nanocrystals are discussed.
Lead‐free double perovskites (DPs) with unique optical properties are of interest for broad applications. However, improving near‐infrared (NIR) photoluminescence (PL) in lead‐free DPs is still a ...challenge. Herein, in order to increase the NIR PL intensity and extend the infrared multicolor luminescence, transition metal Mn2+ is doped into Cs2NaBi1−xErxCl6 lead‐free DPs. Steady‐state and time‐resolved PL studies show that efficient energy transfer from Mn2+ to Er3+ is obtained, leading to NIR PL at ≈1.54 µm can be enhanced 11‐fold compared to Er3+ singly alloyed sample and a PL quantum yield of ≈14.2%. Moreover, the Mn2+‐mediated sensitized strategy can expand to other NIR lanthanide ions (Ho3+ at ≈0.98 µm or Nd3+ at ≈1.07 µm). The as‐synthesized Mn2+ doped Cs2NaBi1−xErxCl6 DPs exhibit robust stability against heat, ultraviolet light, and environmental oxygen/moisture. Finally, the lead‐free DPs phosphor‐converted multifunctional white light‐emitting diode device containing visible and NIR light is fabricated. This work guides constructing energy transfer pathways in DPs and opens new perspectives for the development of lanthanide‐functionalized DPs as promising materials for optoelectronic devices operating in the NIR region.
Mn2+ ions doped Cs2NaBi1−xLnxCl6 (Ln = Er, Ho, Nd) double perovskites are designed and synthesized. The Cs2NaBi0.86Er0.14Cl6:0.42%Mn sample shows enhanced near‐infrared (NIR) photoluminescence (PL) at 1540 nm by 11 times and PL quantum yield of 14.2%. Moreover, Mn2+‐mediated sensitized strategy further expands to other NIR lanthanide ions Ho3+ (≈0.98 µm) or Nd3+ (≈1.07 µm) and the NIR emission intensity can be strongly enhanced.
Perovskite nanocrystals (NCs) are considered as the next‐generation platforms for optoelectronic applications, but their poor stability greatly restricts their development. Here, we present a facile ...composite strategy to synthesize highly stable CsPbBr3/Pb‐MA composite by in situ embedding the CsPbBr3 NCs in a C16H14Br2O6Pb2 (Pb‐MA) organometallic compound (MOC). The CsPbBr3/Pb‐MA composite powders show intense green emission at 519 nm, with a photoluminescence quantum yield of about 48.5% and a full width at half‐maximum of about 17 nm. More interestingly, benefitted from the protection of MOC, the CsPbBr3/Pb‐MA composites can maintain 43% and 83% of initial intensity after being illuminated under blue light for 36 h and being immersed in water for 192 h, respectively. Compared to the original CsPbBr3 NCs, the light/water stability of CsPbBr3/Pb‐MA composites is enhanced by about 40 and 700 times (the PL intensities maintain at about 60% of the initial one), respectively. As a proof‐of‐concept, the as‐fabricated devices exhibit a wide color gamut, 97.7% and 98.2% of Rec. 2020 for white light‐emitting diodes and laser diodes, respectively. These findings demonstrate that the combination of MOC and perovskite NCs is an optimized strategy for the exploitation of high‐performance perovskite composites for their future optoelectronic applications.
A stable lead‐based C16H14Br2O6Pb2 (Pb‐MA) organometallic compound is designed and synthesized, as the framework for the perovskite NCs. The obtained CsPbBr3/Pb‐MA composites show excellent stability and optical performance. The display devices based on the composites exhibit a wide color gamut, 97.7% of Rec. 2020 for white light‐emitting diodes and 98.2% of Rec. 2020 for laser diodes.
Environment-friendly lead-free perovskite nanocrystals (NCs) are highly desirable in terms of optoelectronic applications. Reported herein is the synthesis of perovskite-related Cs
3
Sb
2
Br
9
NCs ...through a simple hot-injection approach. The morphologies and optical properties of NCs were controlled and optimized by varying the reaction temperature, time, and volume of surface ligands. Meanwhile, the Cs
3
Sb
2
Br
9
NCs showed bandgap emission in the blue region centered at 470 nm, and 63 nm full width at half maximum (FWHM). In addition, the Cs
3
Sb
2
Br
9
NCs displayed high stability when immersed in a polar solvent like ethanol. It was also found that the bandgaps of the Cs
3
Sb
2
Br
x
I
9-x
NCs could be adjusted by regulating the composition of halogen.
Recently, CuInS2/ZnS nanocrystals (CISZ NCs) have been widely used in many fields due to their excellent properties, such as tunable photoluminescence (PL) spectra, broad absorption, and ...non-toxicity. In order to expand the application of CISZ NCs, Gd3+ was introduced into the host serving as paramagnetic modules to achieve magnetic resonance imaging (MRI) enhancement. MRI probes could provide high-resolution anatomical information. The derived Gd-Cu-In-S/ZnS nanocrystals (GCISZNCs) exhibited the strong orange photoluminescence with a quantum yield of 57.6% and significantly high longitudinal relaxivity (r1=20.4 mmol/s) in comparison with commercial Magnevist (Gd-DTPA, r1=4.5 mmol/s). Effective enhancement of MRI and improved longitudinal relaxivity as well as lower cytotoxicity mode GCISZ NCs an ideal MRI probe, suggesting its potential and significance in practical biological and clinic applications in the future.
(a) Linear relationship between T1−1 and Gd3+ concentrations, (b) T1-weighted MRI (top) and corresponding pseudo-color images (bottom) of GCISZ NCs with different Gd3+ concentrations (The value of T1−1 was collected basing on readings from (b))
The colloidal cesium lead halide perovskite nanocrystals (NCs) have attracted much attention over the past five years as a promising class of material with potential application in wide-color-gamut ...backlight display because of their high photoluminescence quantum yield (PLQY) and narrow-band emission (full-width at half-maximum, FWHM < 35 nm). To controllably synthesize perovskite NCs, the effects of reaction temperature and reaction time on structure, morphology, particle size and photoluminescence (PL) properties of the NCs were systematically investigated inthis article. Based on these results, the formation kinetics of the perovskite NCs was analyzed and disclosed in further. Finally, a white light-emitting diode (WLED) was prepared by using synthesized CsPbBr3 NCs and K2SiF6:Mn4+ phosphors as the color converters. The WLED exhibits the bright white emission with a CIE chromaticity coordinate of (0.389, 0.376) and a wide color gamut of 123% of NTSC, indicating a potential application in the field of wide color gamut displays in the future.
•The effect of reaction conditions on perovskite NCs were studied systematically.•Explore the kinetics of CsPbX3 (X = Cl, Br, I) NCs growth and synthesizing.•Fabricated the WLED generating the bright white emission with wide color gamut of 123% of NTSC at a driving current of 20 mA.
Display omitted
•FCNPs co-doped with N, P and Ca were obtained via a simple treatment of sesame.•The FCNPs exhibit bright fluorescence, low toxicity, and good bio-compatibility.•The FCNPs show ...excellent performances in bio-imaging.•The FCNPs were successfully applied as a Fe3+ and F− detection platform.•The FCNPs were employed as a fluorescence ink.
Fluorescent carbon nanoparticles (FCNPs) are promising fluorescence probes with potential applications in sensors, bio-imaging, photo-catalysis, ion detection, fluorescent inks and other areas, mainly due to their high stability, low toxicity and cost-effectiveness. However, the relatively low quantum yield (QY) and complex synthesis routes usually hinder their applications. Here, highly efficient FCNPs doped with N, P and Ca ions have been prepared via a simple hydrothermal process using green natural raw materials of sesame as precursors. The products emit strong blue fluorescence with QY as high as 48.5% under 360nm excitation due to the improved electronic characteristics and abundant defect sites induced by natural N, P and Ca ions co-doping. The bright fluorescence, high photostability, ultralow toxicity and good biocompatibility endow as-prepared FCNPs with great potential applicatios in bio-imaging and patterning. Most importantly, as-prepared FCNPs exhibit an extraordinarily high sensitivity and selectivity to Fe3+ ions compared to other metal ions in aqueous solution. The fluorescence intensity is inversely proportional to the concentration of Fe3+ ions, and the calibration curve displays linear regions over the range of 0–90nM with a low limit of detection (LOD) of 1.5nM. Meanwhile, it shows a “turn-on” fluorescence response to F− with good linearity at 10–60nM and a LOD of 2.4nM. These results indicate that FCNPs, as a fluorescent sensing platform, could meet the selective requirements for biomedical analysis and environmental monitoring.
The high quality CsPbBr3-Cs4PbBr6 perovskite composites solids were synthesized by a single atomic supersaturated recrystallization method.
Display omitted
Here, we present a single atomic ...supersaturated recrystallization method to synthesize the green-emitting CsPbBr3-Cs4PbBr6 perovskite composites in solid state with the highest PLQY of 40.8% in pure polar solvent. The component, morphology, and optical properties of the microcrystals can be tuned by varying growth time, the content of ammonium bromide, and bromine source. The developed method provides a new route to large-scale synthesize high quality perovskite composites emitters for light-emitting diodes.
The in-situ growth of CsPbBr3 perovskite quantum dots (QDs) inside glass has been regarded as an alternative approach to improve their stability. Alkaline-earth metal oxides has multiple effects on ...the structure of the glass network. Herein, four types of alkaline-earth metal oxides are introduced into borosilicate glasses to modulate glass network structure, which has quite different effects on the crystallization behavior of CsPbBr3 QDs. The reason can be ascribed to the different impacts of alkaline-earth metal on phase separation, nucleation, and growth procedure. Moreover, CsPbBr3 QDs embedded in glass (CsPbBr3 QD@glass) exhibit superior thermostability and photostability compared with CsPbBr3 QDs powder. Finally, a white light-emitting diode achieving 124% of National Television System Committee (NTSC) gamut is fabricated using the CsPbBr3 QD@glass, K2SiF6:Mn4+ phosphor film, and blue chip-on-board. This work provides a reference for modulating the glass network modifiers to regulate the crystallization behavior of perovskite QDs.
Display omitted
•A aqueous synthesis method is adapted for CsPbBr3/PbBrF composites NCs.•The CsPbBr3 NCs are transformed from CsPb2Br5 NCs by Hydrofluoric acid.•The CsPbBr3/PbBrF composite NCs show excellent ...stability.
All inorganic lead cesium halide perovskites (CsPbX3, X = Cl, Br, I) nanocrystals (NCs) are supposed to be promising luminescent-converting materials for next-generation displays, on account of their excellent optical and photoelectric properties, facile synthesis, and low cost. However, the inherent poor stability hinders their implementation in practical applications. Here, we present a simple cooperative strategy for the synthesis of stable green perovskite composite luminophore powders. In a typical cooperative process, HF leads to the formation of PbBrF framework in which the green-emitting CsPbBr3 NCs that are transformed from the non-emitting precursors CsPb2Br5 NCs by hydration, are simultaneously embedded in. The obtained CsPbBr3/PbBrF composites NCs maintain photoluminescence quantum yield (∼ 30%) and narrow band emission (∼ 22 nm). Additionally, benefiting from the PbBrF framework with good thermal diffusivity and stability, CsPbBr3/PbBrF composite NCs show excellent stability to heat, radiation, and polar solvents, which can be used as promising green luminescent-converting materials in the next-generation displays.
PDF
