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Lead halide perovskite quantum dots (LHP QDs) emerge as versatile photonic sources in electroluminescence and laser devices. Their applications in optoelectronic devices are hindered by surface distortion and ligand stripping during the purification process. In addition, the device performance roll‐off suffers from the ultrafast non‐radiative Auger recombination (AR). To address these issues, herein, CsPbBr3 QDs are prepared with sizes ranging from 6.5 to 9.2 nm and the universal surface repairing strategy is proved to efficiently increase the biexciton lifetime and quantum yield up to 1.4 and 3 times, respectively. The strategy provides a PbBrx rich surface and strong binding didodecyldimethylammonium bromide (DDAB) ligands to achieve near‐unity photoluminescence efficiency, which significantly improves their stability against anti‐solvents and aging in ambient conditions. A single‐mode laser device is realized by self‐assembling the QDs into superlattice as optical microcavity, with low threshold of 9.45 µJ cm−2, quality factor of 2187 and ultrafast lifetime of 3.22 ps. The superlattice laser is demonstrated as an optical encoder with large coding bandwidth of 0.133 THz. This work proposes new insight into the non‐radiative AR process in these single‐component CsPbBr3 QDs, and will pave the way for optoelectronic devices working in intense conditions. [ABSTRACT FROM AUTHOR]

Physically unclonable functions (PUFs) have emerged as the most effective method against counterfeiting, leveraging the intrinsic randomness of objects to avoid data replication. However, despite their efficacy, the complexity and high cost of most PUF‐based counterfeiting labels hinder their practical application. Here, a high‐capacity PUF label based on vertically aligned perovskite nanowire (NW) arrays is demonstrated. The NW arrays are conveniently constructed using a low‐cost solution process using an anodized aluminum oxide template. Each pixel within the label is composed of closely packed CsPbBr3 NW arrays of different lengths, resulting in varied lasing signals. The collected signal of each pixel emerged from the lasing output of the NW arrays, generating high‐density and nonuniform multiple‐mode lasing to facilitate information encoding. A quaternary encoding mechanism is used to encode the number of laser modes per pixel. Impressively, it exhibits a mapping resolution of 1600 pixels within 400 µm2, achieving an impressive encoding capacity (1.97 × 10963) and a pixel density (4 bits µm−2) in this compact area. This work shows a promising approach for anticounterfeiting applications because of its simplicity, low cost, and high encoding capacity. [ABSTRACT FROM AUTHOR]

Optically transparent metamaterial absorbers have unexceptionally encountered a great challenge in further improving optical transparency ranging from visible (Vis) to near‐infrared (NIR) and environmental applicability, due to the limitations of constituent materials and multilayer structures. To overcome this limitation, a highly Vis‐NIR transparent metamaterial‐window with outstanding microwave broadband absorption and practical durability is proposed in this paper, which adopts a typical sandwich structure consisting of a cross‐ and cross‐ring‐shaped resonator and a reflective backplane, separated by a quartz glass. Experimental results indicate that the proposed metamaterial‐window achieves >80% absorptivity, covering a wide frequency range of 6.6–13.8 GHz with a relative bandwidth of 70.59%, while the measured shielding effectiveness is >16.94 dB, at 4.0–16.0 GHz. In addition, the corresponding physical mechanism is revealed by exploiting a classical multiple reflections interference model. More significantly, both the patterned resonator and backplane layers are formed by microscale gold meshes with high Vis‐NIR transmittance and environmental resistance, thereby enabling excellent salt spray corrosion resistance and high‐temperature stability, as well as an average optical transmittance of ≈87.35% at 400–1 800 nm. These advantages endow the design a promising candidate for addressing anti‐electromagnetic interference and electromagnetic shielding both in military and civilian. [ABSTRACT FROM AUTHOR]

Metasurface absorbers (meta‐absorbers) are highly compelling in modern optoelectronic devices. However, owing to the limitations of the sandwiched design framework, conventional meta‐absorbers are restricted to fully absorbing only one‐sided incident waves while completely reflecting the electromagnetic (EM) waves from the opposite direction. In addition, the existing absorbers are opaque and their absorption performances are fixed after the initial design. Here, an optically transparent meta‐absorber consisting of bilayer indium tin oxide patterned layers that can achieve bidirectional and broadband absorption in the microwave frequency range is demonstrated. The inherent physics of bidirectional absorption can be attributed to the interference between multiple reflections and transmissions of EM waves. Furthermore, it is demonstrated that the absorption properties of the proposed meta‐absorber can be continuously switched via coherent control by adding another microwave beam to the other side of the meta‐absorber and manipulating the phase difference between the two input waves. The results indicate that the proposed design can enrich the functionalities of few‐layer metasurfaces and break new ground for EM shielding optical windows. [ABSTRACT FROM AUTHOR]

Optical coding is widely applied in communication and data processing fields due to its practical and powerful characteristics, such as high transmission rate and operational convenience. However, improvements in the loading information capacity of optical encoders always result in increased energy consumption. It is a challenge to realize an optical encoder that combines energy savings, high bandwidth, and miniaturization. Here, both the concept and the demonstration of a perovskite sub‐micro‐encoder with an 84% energy‐saving efficiency and a tunable bandwidth of up to 200 GHz are reported. The way to code the radiative dynamics of the light source allows for the reduction of unnecessary energy consumption from the initial stage through the control of the radiation core. Moreover, the miniature encoder generates code sequences of good coherence, stimulating the development of perovskite‐based optical microchips for ultrafast information processing. [ABSTRACT FROM AUTHOR]

Cavity‐enhanced superfluorescence (CESF) in quantum dot (QD) system is an ultrafast and intense lasing generated by combination of quantum coupling effect and optically stimulated amplification effect, which can provide a new idea for realizing high quality blue light sources and address the limitation of conventional inefficient blue light sources. Modifying halide composition is a straightforward method to achieve blue emission in perovskite QD system. However, the spectral instability introduced by photoinduced halide phase segregation and low coupling efficiency between QDs and optical cavities make it challenging to achieve stable blue CESF in such halide‐doped QD system. Herein, long‐range‐ordered, densely packed CsPbBr2Cl QD‐assembled superlattice microcavities in which the two core issues can be appropriately addressed are developed. The QD superlattice structure facilitates excitonic delocalization to decrease exciton‐phonon coupling, thus alleviating photoinduced phase segregation. By combination of theoretical analysis and temperature‐dependent photoluminescence (PL) measurements, the underlying photoinduced phase segregation mitigation mechanism in mixed halide superlattices is clarified. Based on the CsPbBr2Cl QD superlattices with regularly geometrical structures, in which the gain medium can be strongly coupled to the naturally formed microcavity, stable and ultrafast (3 ps) blue CESF with excellent optical performance (threshold ≈33 µJ cm−2, quality factor ≈1900) is realized. [ABSTRACT FROM AUTHOR]

Integrating broadband absorption, dynamic tunability, and high optical transparency into a single microwave absorber remains a crucial challenge. Here, an ultra‐broadband, tunable, and transparent microwave meta‐absorber comprising double‐layer indium tin oxide resonant patterns and a water‐based substrate is theoretically presented and experimentally demonstrated. Experimental measurements indicate that the designed meta‐absorber can achieve over 90% absorption in an ultra‐broadband frequency range of 12.49–98.21 GHz with a relative bandwidth of 154.9%, while the average optical transmittance is 60.49%. In addition, a multiple reflections interference model is employed to elucidate the physical mechanisms of the ultra‐broadband absorber. Furthermore, its absorption performance can be reversibly switched between ultra‐broadband and dual‐broadband by altering the water substrate thickness. These peculiar properties make the proposed meta‐absorber more favorable for practical applications in modern stealth materials and optical windows. [ABSTRACT FROM AUTHOR]

Single perovskite alloy micro‐nano structure capable of emitting multi‐wavelength tunable lasing is desirable for its potential application in highly integrated photonic devices. However, owing to the soft and dynamic crystal lattice of perovskite and the low mobility energy of halide anion, it is still a challenge to obtain alloy micro‐nano structures with a stable bandgap gradient. Herein, based on the highly ordered superlattice consisting of well‐separated individual quantum dots and precise anion exchange strategy, a single perovskite alloy superlattice is obtained with a widely tunable bandgap. The photoluminescence (PL) spectra results indicate that the stability of the bandgap difference of the alloy superlattice sample is approximately 10 times higher than that of the previously reported perovskite single‐crystal alloy nanowires. By combination of quantitative study based on confocal PL measurements and theoretical calculations, the kinetics and atomic‐scale anion exchange mechanism are analyzed, the latter being responsible for the formation of stable bandgap gradient in the alloy superlattice. Multi‐wavelength lasing is further realized in single alloy superlattice. In addition, carrier transportation dynamics reveals the energy‐transfer process in the alloy superlattice, explaining the difficulties of realizing multicolor lasing. The work provides a new approach to solving problems in the field of stable multicolor microlasers. [ABSTRACT FROM AUTHOR]

Figuring out the inner mechanism of lattice distortion and unstable factors of inorganic perovskite nanocrystals in solvents is essential for fundamental studies and applications in photonic devices. Traditional research results simply ascribed the unstable factor to solvent polarity, which in fact are insufficient and inaccurate to explain some phenomena. Here, we propose a molecular level mechanism that the crucial cause for the instability of perovskite nanocrystals in solutions is the competition between complex bond energies in colloidal nanocrystals system. In combination with molecular dynamics simulations and first principle calculations, the kinetic process of lattice distortion and self‐assembly of perovskite nanocrystals is revealed in solutions. By tailoring the relative magnitude of the hydrogen bond energy between ligand ammonium ion and halogen, the van der Waals force between the ligands of adjacent nanocrystals and the bond energy between lead atom and halogen, nanocrystal arrays and single‐crystalline nanowires based on all‐inorganic perovskite nanocrystals can be freely obtained. Moreover, the polarization properties of the obtained nanowires are studied, which are related to their formation process. [ABSTRACT FROM AUTHOR]

Cavity‐enhanced superfluorescence is an ultrafast and intense lasing produced by strong interaction between superfluorescence and optical cavity. However, due to the quite difficulty of particle cooperative emission in solid‐state systems, and the low coupling efficiency between superfluorescence and optical cavity, research on ultrafast optical properties of cavity‐enhanced superfluorescence is thus far in its infancy. Fortunately, perovskites being made into quantum dot superlattice microcavity is an excellent candidate as such light source. This work reveals the time‐dependent redshift process of cavity‐enhanced superfluorescence under high‐power injection, and interprets the physical mechanism of lasing broadening with increasing power from the dynamic perspective. At the same time, the multi‐mode lasing dynamic photoluminescence image output at different times is also tracked. The short‐wavelength resonance mode has a lower stimulated threshold, but its radiation lags behind the long‐wavelength resonance mode by 4 ps in high excited density. These ultrafast optical property researches may promote the application of quantum dot superlattices in information technology, optical communications, ultrafast lasers, and other fields. [ABSTRACT FROM AUTHOR]

Chiral resolution of binaphthylamine is often a toilful conundrum in the field of analytical chemistry and biomedicine. The work puts forward a selective, sensitive, and miniaturized analytical method based on molecularly imprinted polymers (MIPs) as adsorbent for miniaturized tip solid‐phase extraction (MTSPE) in the separation of binaphthylamine enantiomer. This method combines the advantages of MIPs (high selectivity), MTSPE (low consumption), and high‐performance liquid chromatography (HPLC, high sensitivity). A simple synthesis methodology of MIP (P2) was conducted through bulk polymerization with (S)‐(−)‐1,1′‐binaphthyl‐2,2′‐diamine (S‐DABN) as template together with methacrylic acid monomer, and ethylene glycol dimethacrylate as cross‐linker in proper porogen, realizing a selective recognition and efficient enrichment for S‐DABN. The method exhibited appreciable linearity (0.06–1.00 mg ml−1), low quantification limit (0.056 mg ml−1), good absolute recoveries (45.70%–69.29%), and high precision (relative standard deviations ≤ 3.54%), along with low consumption (0.50 ml sample solution and 25.0 mg adsorbent). Based on the density functional theory, computational simulation was used to make a preliminary prediction for rational design of MIPs and gave a reasonable elaboration involving the potential mechanism of templates interacting with functional monomers. The adsorption kinetics and thermodynamics were investigated to evaluate the recombination process of substrates. In addition, the selectivity of MIPs for S‐DABN was obtained by MIP‐MTSPE coupled with HPLC, which supports the feasibility of this convenient design process. The proposed method was employed for selective extraction of S‐DABN and exhibited promising potential in the application of chiral analysis. [ABSTRACT FROM AUTHOR]

Two novel helical poly(phenylacetylene) derivatives containing chiral phenylethyl carbamate residues in the end of each side chain (PPA‐S and PPA‐R) were synthesized by polymerization of the corresponding phenylacetylene monomers using Rh(nbd)BPh4 as a catalyst in DMF. The enantioseparation properties of the polymers were evaluated as coated‐type chiral stationary phases (CSPs) for high‐performance liquid chromatography (HPLC). Under the same chromatographic conditions, PPA‐S and PPA‐R showed different enantioseparation properties, indicating that the different interactions between the analytes and the polymers, which result from the different chiral phenylethyl carbamate groups in the end of each side chains. Racemates 1, 7, and 8 could be better resolved on PPA‐S, while racemate 6 was separated on PPA‐R more efficiently. In addition, the coated‐type CSPs showed good solvent tolerability and could work without any damage by introducing the polar solvents, such as CHCl3 and THF, in eluent. Moreover, some racemates could be better resolved on these coated‐type CSPs with the addition of THF to the eluent. [ABSTRACT FROM AUTHOR]

Perovskites—energy‐conversion materials with light‐absorbing and electronic transport properties—have shown excellent features for developing photovoltaic devices and novel light sources. It is an open challenge to extend the application of perovskites, such as to the field of ultrafast information coding. This work demonstrates a terahertz coding of optical polarization degree based on a metal halide perovskite nanostructure. Sub‐micrometer spheres of all‐inorganic CsPbBr3 perovskite are fabricated with high quality and stability. By employing this perovskite nanostructure, the ultrafast coding of degree of linear polarization (DLP) is achieved with a tunable bandwidth of up to 0.1 THz. Moreover, the DLP coding can be combined with the coding of another parameter, i.e., the shape of the lasing pulse, which improves the high‐bandwidth encoder from binary to ternary. The all‐photonic miniature encoder generates multiple‐parameter THz code sequences, stimulating the development of perovskite‐based microdevices for ultrafast information processing. [ABSTRACT FROM AUTHOR]

Rubidium lead halides (RbPbX3), an important class of all‐inorganic metal halide perovskites, are attracting increasing attention for photovoltaic applications. However, limited by its lower Goldschmidt tolerance factor t≈0.78, all‐inorganic RbPbBr3 has not been reported. Now, the crystal structure, X‐ray diffraction (XRD) pattern, and band structure of perovskite‐phase RbPbBr3 has now been investigated. Perovskite‐phase RbPbBr3 is unstable at room temperature and transforms to photoluminescence (PL)‐inactive non‐perovskite. The structural evolution and mechanism of the perovskite–non‐perovskite phase transition were clarified in RbPbBr3. Experimentally, perovskite‐phase RbPbBr3 was realized through a dual‐source chemical vapor deposition and annealing process. These perovskite‐phase microspheres showed strong PL emission at about 464 nm. This new perovskite can serve as a gain medium and microcavity to achieve broadband (475–540 nm) single‐mode lasing with a high Q of about 2100. [ABSTRACT FROM AUTHOR]

Due to the urgent demand for portable electronics, enormous research efforts are devoted for the development of flexible, wearable and lightweight supercapacitors. Herein, we report a cost‐effective chemical liquid process followed with a refluxing route to grow CC@CoMoO4‐Co(OH)2 nanosheets with Co‐based MOF as precursor. The resulting CC@CoMoO4‐Co(OH)2‐4 electrode delivers a significantly enhanced specific capacitance of 2028 F g−1 at 1 A g−1 and capacitance of 1581.8 F g−1 at 20 A g−1. Furthermore, the flexible all‐solid‐state asymmetric supercapacitor (CC@CoMoO4‐Co(OH)2//AC) is assembled, displays a high energy density of 61 Wh kg−1 at power density of 800 W kg−1, with an excellent cycle stability. These exceptional electrochemical performances could be ascribed to the unique structure and multi‐metal ion combination contributes to the ideal synergistic effects, which also signify that the potential application of CC@CoMoO4‐Co(OH)2 nansheets in high‐performance supercapacitors. [ABSTRACT FROM AUTHOR]

A novel one‐handed helical poly(phenylacetylene) bearing L‐hydroxyproline pendants (poly(PA‐P)) was synthesized as an eco‐friendly polymer‐supported catalyst for asymmetric reactions. The helical poly(PA‐P) catalyzed the asymmetric aldol reactions of cyclohexanone with p‐nitrobenzaldehyde, and showed good recyclability and higher enantiomeric excess (ee) in aqueous medias than that in organic medias. The one‐handed helicity of poly(PA‐P) was clearly affected by the water content in the aqueous media. The helical poly(PA‐P) showed the higher enantioselectivity (ee = 99%) than its monomer PA‐P (ee = 54%) in THF/H2O (H2O vol % = 25.0 vol %). After the one‐handed helical structure of poly(PA‐P) was destroyed by grinding treatment, the ee of the reaction clearly decreased from 99 to 49%. These indicate that the one‐handed helical structure of poly(PA‐P) played an important role in the high enantioselectivity of the asymmetric aldol reactions in the aqueous media. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1024–1031 A novel helical poly(phenylacetylene) (poly(PA‐P)) was synthesized, which successfully catalyzed the asymmetric aldol reaction in aqueous media. The easily recyclable polymer‐supported catalyst (poly(PA‐P)) showed higher enantioselectivity (99% ee) and diastereoselectivity (99/1) than the monomer catalyst (PA‐P) at the same condition, indicating a synergistic effect of the macromolecular helicity. [ABSTRACT FROM AUTHOR]

Acrylamide (AM) was copolymerized with ethylene glycol dimethacrylate (EGDMA) in the presence of ( R)-1,1′-binaphthalene-2-naphthol (BINOL) as the template molecules on the surface of silica gel by a free radical polymerization to produce a chiral stationary phase based on the surface molecularly imprinted polymer (SMIP-CSP). The SMIP-CSP showed a much better separation factor ( α = 4.28) than the CSP based on the molecularly imprinted polymer (MIP-CSP) without coating on the silica gel ( α = 1.96) during the chiral separation of BINOL enantiomers by high-performance liquid chromatography. The influence of the pretreatment temperature and the content of the template molecule (( R)-BINOL) of the SMIP-CSP, and the mobile phase composition on the separation of the racemic BINOL were systematically investigated. [ABSTRACT FROM AUTHOR]

A distinct “split and recoalescence” growth mechanism of tubular ZnO micro/nanostructures is observed for the first time. On the basis of experimental growth studies and first‐principles calculations, it is proposed that H2/H2O vapor, added to the traditional carbothermal reduction process, changes the intrinsic surface energy of ZnO crystal, which affects the ZnO crystal growth mode and subsequently controls the geometry of ZnO micro/nanotubes. It is shown that these tubular ZnO micro/nanostructures exhibit regular hexagonal cross sections and smooth outer and inner surfaces. Optical studies of ZnO micro/nanotubes reveal characteristic coherent intensity modulations of their emission spectra which reflect the excitation of either whispering gallery modes or wave‐guided modes. The specific type of mode can be selected by controlling the microtube geometry, specifically by its wall thickness to diameter ratio, as demonstrated both experimentally by photoluminescence spectroscopy, and theoretically by finite‐element‐method simulations. [ABSTRACT FROM AUTHOR]

Single‐crystalline Sb shallow‐doped ZnO microwire wave‐guided optical resonators are synthesized via a simple carbothermal reduction method. The formation of the ZnO wave‐guided microcavities are investigated systematically, and the Sb film formed on the substrate is confirmed to be the critical factor in crystal growth. The optical signals of the annealed ZnO microcavities induced by the Sb related acceptor defects are clarified through a low‐temperature spectrum detection technology. Excitation power and temperature dependence of UV lasing properties of the ZnO microcavities annealed in different atmospheres are studied. The results reveal that such high‐quality Sb shallow‐doped ZnO wave‐guided microcavities have excellent optical responses and a strong light‐field regulation capability, which would greatly promote the development of ZnO cavity‐based photoelectronic devices. [ABSTRACT FROM AUTHOR]

The exploration of cooperative states in many‐body systems is a key research area. It focuses on superfluorescence (SF), a phenomenon linked with radiative dipole coupling, and its intersection with classical lasing effects. This produces a unique lasing‐field‐hybrid cooperative dipole (LCD) state through optical cavity‐enhanced superfluorescence (CESF). A coherent energy transfer is demonstrated between two such states within a perovskite quantum dot (QD) superlattice. This results in competitive luminescence timing dynamics. The findings reveal that stimulated energy transfer occurs when two cooperative cavity‐exciton states coexist, controllable via a dual‐pulse pump technique. This understanding is vital for advancing quantum phenomena knowledge and enhancing optoelectronic devices. [ABSTRACT FROM AUTHOR]

The realization of ultrahigh quality upconverted single‐mode lasing in wavelength‐scale cavity is still a great challenge, because of limitation of microcavity quality, gain medium, and low spontaneous emission coupling efficiency β. In this work, it is demonstrated that inorganic cesium lead bromide (CsPbBr3) perovskite spheres with size of ≈780 nm serve as a gain medium and whispering‐gallery cavity simultaneously for two‐photon excited single‐mode laser. Lasing mode with a very narrow linewidth (≈0.037 nm) is realized, corresponding to an ultrahigh Q factor ≈1.5 × 104. Surprisingly, the lasing performance of such small microcavity is best among reported naturally formed semiconductor microcavities. Furthermore, room‐temperature single‐mode lasing at same wavelength can be obtained at any angle between −30° and 30°, showing the nearly uniform emission output of the spherical microcavity. This work paves a simple and straight way to obtain ultrahigh Q two‐photon excited single‐mode lasing in micro/nanostructures, holding great promise for practical applications in frequency upconversion, high sensitive sensing in nano‐optics. Ultrahigh quality upconverted single‐mode lasers in individual all‐inorganic CsPbBr3 sub‐micrometer spherical whispering‐gallery mode microcavities are realized. The upconverted single‐mode laser exhibits ultrahigh Q factor (≈1.5 × 104) and very small linewidth (≈0.037 nm) in such a sub‐micrometer spherical (D < 1 µm) cavity, which is the best in all the reported natural nano/microcavity lasers. [ABSTRACT FROM AUTHOR]