Impurity doping is an effective approach to tuning the optoelectronic performance of host materials by imparting extrinsic electronic channels. Herein, a family of lanthanide (Ln
) ions was ...successfully incorporated into a Bi:Cs
AgInCl
lead-free double-perovskite (DP) semiconductor, expanding the spectral range from visible (Vis) to near-infrared (NIR) and improving the photoluminescence quantum yield (PLQY). After multidoping with Nd, Yb, Er and Tm, Bi/Ln:Cs
AgInCl
yielded an ultrabroadband continuous emission spectrum with a full width at half-maximum of ~365 nm originating from intrinsic self-trapped exciton recombination and abundant 4f-4f transitions of the Ln
dopants. Steady-state and transient-state spectra were used to ascertain the energy transfer and emissive processes. To avoid adverse energy interactions between the various Ln
ions in a single DP host, a heterogeneous architecture was designed to spatially confine different Ln
dopants via a "DP-in-glass composite" (DiG) structure. This bottom-up strategy endowed the prepared Ln
-doped DIG with a high PLQY of 40% (nearly three times as high as that of the multidoped DP) and superior long-term stability. Finally, a compact Vis-NIR ultrabroadband (400~2000 nm) light source was easily fabricated by coupling the DiG with a commercial UV LED chip, and this light source has promising applications in nondestructive spectroscopic analyses and multifunctional lighting.
This work reports a novel dual-phase glass containing Tm:NaYbF4 upconverting nanocrystals (UCNCs) and CsPbBr3 perovskite nanocrystals (PNCs). The advantages of this kind of nanocomposite are that it ...provides a solid inorganic glass host for the in situ co-growth of UCNCs and PNCs, and protects PNCs against decomposition affected by the external environment. Tm:NaYbF4 NC-sensitized stable CsPbBr3 PNCs photon UC emission in PNCs is achieved under the irradiation of a 980 nm near-infrared (NIR) laser, and the mechanism is evidenced to be radiative energy transfer (ET) from Tm3+: 1G4 state to PNCs rather than nonradiative Förster resonance ET. Consequently, the decay lifetime of exciton recombination is remarkably lengthened from intrinsic nanoseconds to milliseconds since carriers in PNCs are fed from the long-lifetime Tm3+ intermediate state. Under the simultaneous excitation of the ultraviolet (UV) light and NIR laser, dual-modal photon UC and downshifting (DS) emissions from ultra-stable CsPbBr3 PNCs in the glass are observed, and the combined UC/DS emitting color can be easily altered by modifying the pumping light power. In addition, UC exciton recombination and Tm3+ 4f–4f transitions are found to be highly temperature sensitive. All these unique emissive features enable the practical applications of the developed dual-phase glass in advanced anti-counterfeit and accurate temperature detection.
Efficient antiviral drug discovery has been a pressing issue of global public health concern since the outbreak of coronavirus disease 2019. In recent years, numerous in vitro and in vivo studies ...have shown that 25-hydroxycholesterol (25HC), a reactive oxysterol catalyzed by cholesterol-25-hydroxylase, exerts broad-spectrum antiviral activity with high efficiency and low toxicity. 25HC restricts viral internalization and disturbs the maturity of viral proteins using multiple mechanisms. First, 25HC reduces lipid rafts and cholesterol in the cytomembrane by inhibiting sterol-regulatory element binding proteins-2, stimulating liver X receptor, and activating Acyl-coenzyme A: cholesterol acyl-transferase. Second, 25HC impairs endosomal pathways by restricting the function of oxysterol-binding protein or Niemann-pick protein C1, causing the virus to fail to release nucleic acid. Third, 25HC disturbs the prenylation of viral proteins by suppressing the sterol-regulatory element binding protein pathway and glycosylation by increasing the sensitivity of glycans to endoglycosidase. This paper reviews previous studies on the antiviral activity of 25HC in order to fully understand its role in innate immunity and how it may contribute to the development of urgently needed broad-spectrum antiviral drugs.
Stimuli-responsive smart luminescent materials capable of dynamic color emission with distinct spectral profile/intensity are highly desirable for anti-counterfeiting applications. Here, we report ...the dynamic manipulation of photoluminescence from metal halide CsPbX3 (X = Br, I) perovskite quantum dots (PeQDs) inside a glass medium by tuning local temperature fields in real time in combination with the efficient photothermal material CsYb2F7@glass. Benefiting from the effective protection of the inorganic glass matrix and low exciton binding energy of PeQDs, it is feasible to realize stable and reversible ON/OFF full-spectral emissions of PeQDs upon commercial 980 nm laser stimulation. The dynamic combination of downshifting PeQDs and upconverting lanthanide-doped CsYb2F7 can be elaborately designed to produce a series of erasable photochromic anti-counterfeiting patterns and multi-dimensional optical encodings.
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•An approach to dynamically manipulate PL of CsPbX3 QDs inside glass is developed•Laser-induced Ln3+ photothermal effect is used to lighten/quench PL of CsPbX3@glass•Erasable photochromic anti-counterfeiting and optical encodings are demonstrated
Wang et al. demonstrate the dynamic manipulation of erasable emissions from CsPbX3 perovskite quantum dots (PeQDs) inside a glass medium by tuning local temperature fields in real time with the help of the efficient photothermal material CsYb2F7. This controllable combination of rare-earth/PeQDs may enable their practical application in high-level optical security.
Effects of suction dredging on water quality and zooplankton community structure in a shallow of eutrophic lake, were evaluated. The results showed that a decreasing trend for levels of phosphorus, ...organic matter, total suspended solids, Chlorophyll a and Secchi transparency in the water column was found, while levels of water depth, electrical conductivity, total dissolved solids and NO3^--N concentration increased markedly post-dredging. The effects of dredging on dissolved oxygen, pH value and temperature were almost negligible. The zooplankton community structure responded rapidly to the environmental changes caused mainly by dredging. As a result, the abundance of rotifers decreased, while the density of zooplanktonic crustaceans increased markedly. The representative taxa were Brachionus angularis, B. budapestinensis, B. diversicornis, Synchaeta spp. and Neodiaptomus schmackeri. A distinct relationship between zooplankton taxa composition and their environment, unraveled by a redundancy analysis, indicating that the measured environment contributed to the variations in the zooplankton community structure to some extent. The first four synthetic environmental variables explained 51.7% of the taxonomic structure. Therefore, with the reduction of internal nutrient load and a shift in dominance by less eutrophic species, it inferred that dredging might be one of effective measures for environmental improvements of such lakes.
High‐quality backlit display puts forward urgent demand for color‐converting materials. Recently, metal halide perovskites (MHPs) with full spectral tunability, high photoluminescence quantum yields ...(PLQYs), and high color purity have found potential application in wide‐color‐gamut display. Regrettably, naked MHPs suffer from long‐term instable issue and cannot pass harsh stability tests. Herein, amorphous‐glass‐protected green/red CsPbX3 quantum dots (QDs) are prepared by elaborately optimizing glass structure, perovskite concentration, and in situ crystallization. PLQYs of green CsPbBr3@glass and red CsPbBr1.5I1.5@glass reach 94% and 78%, respectively, which are the highest ones of CsPbX3@glass composites reported so far and comparable to colloidal counterparts. Benefited from complete isolation of QDs from external environment by glass network, CsPbX3@glass can endure harsh commercial standard aging tests of 85 °C/85%RH and blue‐light‐irradiation, which are applied to construct white light‐emitting diodes (wLEDs) with high external quantum efficiency of 13.8% and ultra‐high luminance of 500 000 cd m−2. Accordingly, the perovskite wLED arrays‐based backlit unit and a prototype display device are designed for the first time, showing more vivid and wide‐color‐gamut feature benefited from narrowband emissions of CsPbX3 QDs. This work highlights practical application of CsPbX3@glass composite as an efficient and stable light color converter in backlit display.
High‐quality display puts forward urgent demand for color‐converting materials. Herein, amorphous‐glass‐protected green/red CsPbX3 quantum dots with high emissive yields of 94%/78% and super stability are applied to construct white light‐emitting diodes (wLEDs). A prototype display device based on perovskite wLEDs arrays backlight shows more natural and real color restoration for its wide color gamut feature.
The development of luminescent materials with concurrent multimodal emissions is a great challenge to improve security and data storage density. Lanthanide‐doped nanocrystals are particularly ...appropriate for such applications for their abundant intermediate energy states and distinguishable spectroscopic profiles. However, traditional lanthanide luminescent nanoparticles have a limited capacity for information storage or complexity to shield against counterfeiting. Herein, it is demonstrated that the combination of upconverting and downshifting emissions in a particulate designed lanthanide‐doped core@multishell nanoarchitecture allows the generation of multicolor dual‐modal luminescence over a wide spectral range for complex information storage. Precise control of lanthanide dopants distribution in the core and distinct shells enables simultaneous excitation of 980/808 nm focusing/defocusing laser and 254 nm light and produces complex upconverting emissions from Er, Tm, Eu, and Tb via multiphoton energy transfer processes and downshifting emissions from Eu and Tb via efficient energy transfer from Ce to Eu/Tb in Gd‐assisted lattices. It is experimentally proven that multiple visualized anti‐counterfeit and information encryption with facile decryption and authentication using screen‐printing inks containing the present core@multishell nanocrystals are practically applicable by selecting different excitation modes.
Lanthanide‐doped core@multishell nanoarchitectures are constructed and precise control over dopants distribution in the distinct layers enables diversified excitations from the combination of UV light and near‐infrared (NIR) focusing/defocusing laser, leading to complex upconverting/downshifting combined luminescence in a wide spectral region. Multiple visualized anticounterfeit and information encryption/decryption using screen‐printing inks containing the developed nanocrystals are demonstrated to be practically applicable through appropriately selecting excitation modes.
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•Ultrapure green emissions of glass-stabilized CsPb(Br/I)3 PeQDs are fabricated.•Quantum yields of CsPb(Br/I)3@glass composites are highly dependent on halogen content.•The emissive ...profiles and FWHMs can be well modified by varying Br-to-I ratio in glass.•The issues of instability, adverse anion-exchange and phase separation of colloidal PeQDs can be solved by glass protection.•Prototypical white LEDs are constructed and applied in backlit display, covering up 92% color gamut of Rec. 2020 standard.
CsPbX3 (X = Cl, Br, I) perovskite quantum dots (PeQDs) have potential application in backlit display. However, they generally suffer from instability and shortage of ultrapure tunable green emissions owing to halogen phase separation. This work reports the realization of elaborately tunable green emissions in glass-protected CsPb(Br/I)3 PeQDs, which show the advantage of superior long-term stability and enable them to find promising application in ultra-high definition televisions. CsPbX3@glass composites are fabricated by a facile in-situ glass crystallization strategy and their emissions within the spectral range of 506–532 nm along with narrow full width at half maximum (FWHM) of ~21 nm can be well modified by simply varying Br-to-I ratio in precursor glass. Benefited from the protection of tight glass network, CsPbX3@glass retains 90% luminescence after immersing in water for one month, shows no any loss of luminescence after irradiation by 450 nm LED light and prevents anion-exchange and phase separation completely. As a proof-of-concept experiment, CsPbX3@glass-based on-chip white LED devices are constructed and applied in backlit display, covering up 123% and 92% color gamut of NTSC and Rec. 2020 standards in the CIE 1931 color space, respectively.
Perovskite quantum dots (PeQDs) have been regarded as an alternative to traditional phosphor color converters in the backlit display to improve the color gamut and rendition of LCD. However, the ...pending barriers of aggregation quenching and structure instability are hindering their practical applications. Herein, high-quality CsPbX3 (X = Br, Br/I) PeQDs were in situ precipitated inside glass to produce nanocomposites with superior optical performance and stability. The highest photoluminescence quantum yield (PLQY) of ∼100% for CsPbBr3@glass is ascribed to the elimination of the inner filter effect via a physical dilution approach to restore its apparent value to an intrinsic one, and the exceptional photostability and water/heat resistance are benefited from their effective isolation from the external environment by the surrounding glass network units. Employing the PeQDs@glass@PDMS monolithic film, a high-performance backlit LCD was designed, and its color gamut reached 152% of commercial LCD and 103% of NTSC, demonstrating a great potential in the optoelectronic industry.
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•Effective Ni2+ doping in CsPbI3 nanocrystals is achieved.•Ni2+ doping enables to stabilize cubic CsPbI3 up to 7 months in atmosphere.•Ni2+ doping leads to significantly improve PLQY ...approaching near-unity.•Ni2+-doped perovskite LED outperforms the device using pristine CsPbI3 nanocrystals.•The device exhibits a peak EQE of ~7% and a maximal luminance of 830 cd/m2.
Room temperature phase instability of cubic CsPbI3 perovskite nanocrystals is one of the notorious limitations for practical applications in optoelectronic fields. Herein, the incorporation of Ni2+ ions into CsPbI3 lattice was successfully achieved by a modified hot-injection method using nickel acetate as doping precursor. The as-prepared Ni2+ (3.3 mol%): CsPbI3 nanocrystals exhibited an improved, near-unity (95%~100%) photoluminescence quantum yield owing to the enhanced radiative decay rate and the decreased non-radiative decay rate. Additionally, Ni-doping was demonstrated to stabilize CsPbI3 lattice and the Ni2+: CsPbI3 film and colloidal solution can retain their red luminescence up to 15 days and 7 months in atmosphere, respectively. First-principle calculations verified that the significantly improved optical performance and stability of Ni2+: CsPbI3 nanocrystals arose primarily from the increased formation energy due to the successful doping of Ni2+ in CsPbI3. Benefiting from such an effective doping strategy, the as-prepared Ni2+-doped CsPbI3 perovskite nanocrystals can function well as efficient red-light emitter toward the fabrication of high-performance perovskite LED with a peak external quantum efficiency of ~7%.
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