A novel design of copper selenide/zinc selenide/Nitrogen-doped carbon derived from MOF for sulfadiazine adsorption: Performance and mechanism.

Herein, a novel copper selenide/zinc selenide/Nitrogen-doped carbon (Cu2Se/ZnSe/NC) sphere was constructed via a combination of cation exchange, selenization and carbonization approaches with zinc-based metal-organic frameworks (ZIF-8) as precursor for sulfadiazine (SDZ) removal. Compared with the ZnSe/NC, the defective Cu2Se/ZnSe interface in the optimizing Cu-ZnSe/NC2 sample caused a remarkably improved adsorption performance. Notably, the adsorption capacity of 129.32 mg/g was better than that of mostly reported adsorbents for SDZ. And the adsorption referred to multiple-layer physical-chemical process that was spontaneous and exothermic. Besides, the Cu-ZnSe/NC2 displayed fast adsorption equilibrium of about 20 min and significant anti-interference ability for inorganic ions. Specially, the adsorbent possessed excellent stability and reusability, which could also be applied for rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) dyes removal. Ultimately, the charge redistribution of Cu2Se/ZnSe interface greatly contributes the superior adsorption performance for SDZ, in which electrostatic attraction occupied extremely crucial status as compared to π-π electron-donor-acceptor (π-π EDA) interaction and hydrogen bonding (H-bonding), as revealed by the density function theory (DFT) calculations and experimental results. This study can provide a guideline for design of high-efficient adsorbent with interfacial charge redistribution.

Impacts of substituting magnesium with zinc on crystallization behaviors in an aluminosilicate glass.

A series of zinc-magnesium mixed aluminosilicate glasses with the molar composition (1-r)MgO·rZnO·Al2O3·2.5SiO2, where r = 0.00, 0.25, 0.50, 0.65, 0.75, and 1.00, were fabricated to probe the effects of substitution of magnesium with zinc on crystallization behaviors. Based on the evolution of phase compositions as revealed by calorimetric behaviors and X-ray diffraction patterns, a series of transparent surface crystallized glasses ranging from high transparency for the pure Zn-end member to heavy translucency for the pure Mg-end member were fabricated through heat treatment at the first crystallization peak temperature for 20 min. With the substitution of Mg with Zn, the evolution of morphology unveiled by optical microscopy is ascribed to the alteration of crystal phases formed from the sole metastable Zn-ß quartz solid solution to the coexistence of polycrystal phases containing Zn-ß quartz solid solution, µ-cordierite, or α-cordierite. These findings are very helpful for optimizing the performance of crystallized aluminosilicate glasses.

High-Performance All-Inorganic Architecture Perovskite Light-Emitting Diodes Based on Tens-of-Nanometers-Sized CsPbBr3 Emitters in a Carrier-Confined Heterostructure.

Developing green perovskite light-emitting diodes (PeLEDs) with a high external quantum efficiency (EQE) and low efficiency roll-off at high brightness remains a critical challenge. Nanostructured emitter-based devices have shown high efficiency but restricted ascending luminance at high current densities, while devices based on large-sized crystals exhibit low efficiency roll-off but face great challenges to high efficiency. Herein, we develop an all-inorganic device architecture combined with utilizing tens-of-nanometers-sized CsPbBr3 (TNS-CsPbBr3) emitters in a carrier-confined heterostructure to realize green PeLEDs that exhibit high EQEs and low efficiency roll-off. A typical type-I heterojunction containing TNS-CsPbBr3 crystals and wide-bandgap Cs4PbBr6 within a grain is formed by carefully controlling the precursor ratio. These heterostructured TNS-CsPbBr3 emitters simultaneously enhance carrier confinement and retain low Auger recombination under a large injected carrier density. Benefiting from a simple device architecture consisting of an emissive layer and an oxide electron-transporting layer, the PeLEDs exhibit a sub-bandgap turn-on voltage of 2.0 V and steeply rising luminance. In consequence, we achieved green PeLEDs demonstrating a peak EQE of 17.0% at the brightness of 36,000 cd m-2, and the EQE remained at 15.7% and 12.6% at the brightness of 100,000 and 200,000 cd m-2, respectively. In addition, our results underscore the role of interface degradation during device operation as a factor in device failure.

Blue and white light modulation of a flexible electroluminescent device based on phosphors.

Flexibility, certain mechanical strength, and color modulation are significant elements for flexible optoelectronic devices. However, it is laborious to fabricate a flexible electroluminescent device with balanceable flexibility and color modulation. Here, we mix a conductive nonopaque hydrogel and phosphors to fabricate a flexible alternating current electroluminescence (ACEL) device with color modulation ability. This device realizes flexible strain based on polydimethylsiloxane and carboxymethyl cellulose/polyvinyl alcohol ionic conductive hydrogel. The color modulation ability is achieved by varying the voltage frequency applied on the electroluminescent phosphors. The color modulation could realize blue and white light modulation. Our electroluminescent device exhibits great potential in artificial flexible optoelectronics.

Decoupling the Positive and Negative Aging Processes of Perovskite Light-Emitting Diodes Using a Thin Interlayer of Ionic Liquid.

A positive aging phenomenon, that is, enhancement of the electroluminescence performance at the beginning of electrical aging, is commonly observed for the state-of-the-art perovskite light-emitting diodes (PeLEDs). The origins of positive aging could fundamentally interfere with those of the operational deterioration processes of PeLEDs (namely negative aging), bringing difficulty in analyzing the degradation mechanisms. This work decouples the positive and negative aging processes of PeLEDs by inserting a thin ionic liquid interlayer between the hole-injection layer and the perovskite layer. This interlayer inhibits ions migration by passivating the halogen vacancies of perovskite films and suppresses interfacial exciton quenching, enabling us to decouple the positive and negative aging processes of PeLEDs while increasing the device efficiency. Inserting an ionic liquid interlayer is also demonstrated to be effective for iodide-based PeLEDs and applicable with the use of other ionic liquids. Our work provides an ideal system for fundamental studies on the degradation mechanisms of PeLEDs.

Organic-Inorganic Hybrid SEI Induced by a New Lithium Salt for High-Performance Metallic Lithium Anodes.

The practical application of the metallic lithium anode is suppressed by the highly unstable interface between electrolytes and lithium metal during the process of lithium plating/stripping. A perfect solid electrolyte interphase (SEI) can inhibit detrimental parasitic reactions, thereby improving the cycling performance of the metallic lithium anode. In this work, a high-purity solid lithium difluorobis(oxalato) phosphate (LiDFOP) is synthesized and an outstanding organic-inorganic hybrid SEI is obtained in an ether-based electrolyte for the first time induced by LiDFOP. The preferential reduction of LiDFOP can form an SEI rich in LiF and LixPOyFz species, thereby improving the conductivity and stability of the SEI. In addition, cationic-induced ring-opening polymerization between LiDFOP and 1,3-dioxolane endows the SEI with excellent adaptability to the reiterative volume change of the metallic lithium anode. Therefore, the Li/Cu battery maintains a high coulombic efficiency of 98.37% at a current density of 2 mA/cm2 for 200 cycles, and the Li/Li symmetrical battery shows stable voltage hysteresis over 1000 h even under the condition of 5 mA/cm2. The Li/S battery fabricated employing the electrolyte with LiDFOP shows significant improvement of cycling performance as well. These results manifest that the formation of an organic-inorganic hybrid SEI from LiDFOP can be employed as a new strategy to overcome the problem from the unstable SEI in metallic lithium batteries.

Reversible modification of ultra-broadband luminescence in transparent photonic materials through field-induced nanoscale structural transformation.

The development of integrated multifunctional materials with transparent characteristics meets the requirements of optoelectronics and communication. The coupling of stimuli-responsive materials has become a frequently considered strategy. Experimentalists not only search for photonic materials with excellent physical and chemical properties, but also pursue precise and reversible spectral modification. In this study, the luminescent center Ni2+ is artificially introduced into the transparent LiNbO3 nanoferroelectric photonic materials. The Ni2+ ion-based transparent photonic materials exhibit novel complete ultra-broadband emission in the whole near-infrared region. Until now, the ultra-broadband emission was realized by codoping of several active doping ions. In addition, the emission intensity and wavelength of the luminescent center are modified accurately and reversibly by field-induced nanoscale structural transformation. The Ni2+ ion-based transparent nanoferroelectric photonic materials provide an easy way to develop tunable lasers and ultra-broadband optical amplifiers.

Broadband blue emission from ZnO amorphous nanodomains in zinc phosphate oxynitride glass.

ZnO amorphous nanostructures in a glass matrix show unique optical properties. However, although a ZnO amorphous nanostructure can be formed in some settled multicomponent silicate glasses, the intensity of its emission is extremely weak. Here, to the best of our knowledge, we report a novel and simple zinc phosphate oxynitride glass that can display strong broadband blue emission with a short decay time due to the ZnO amorphous nanostructure in the glass matrix. The result implies that glass topological constraints are the key to forming ZnO amorphous nanostructures. The findings contribute to a deeper understanding of the formation of ZnO amorphous nanostructures in zinc-containing glass.

Tm3+-doped lead silicate glass sensitized by Er3+ for efficient ~2µm mid-infrared laser material.

Er3+/Tm3+ co-doped lead silicate glasses with low phonon (953cm-1) and good thermal stability were synthesized. The ~2µm mid-infrared emission resulting from the 3F4→3H6 transition of Tm3+ sensitized by Er3+ has been observed by 808nm LD pumping. The optimal luminescence intensity was obtained in the sample with 1Tm2O3/2.5Er2O3 co-doped. Moreover, the energy transfer mechanism from Er3+ to Tm3+ ion was analyzed. Absorption and emission cross section have been calculated. The calculated maximum emission cross section of Tm3+ is 2.689×10-21cm2 at 1863nm. Microparameters of energy transfer between Er3+ and Tm3+ ions have also been analyzed. These results ensure that the prepared Er3+/Tm3+ co-doped lead silicate glasses have excellent spectroscopic properties in mid-infrared region and provide a beneficial guide for mid-infrared laser material.

2.8 µm emission and OH quenching analysis in Ho3+ doped fluorotellurite-germanate glasses sensitized by Yb3+ and Er3.

The use of Yb3+ and Er3+ co-doping with Ho3+ to enhance and broaden the Ho3+: 5I6 → 5I7 ~2.8 µm emissions are investigated in the fluorotellurite-germanate glasses. An intense ~3 µm emission with a full width at half maximum (FWHM) of 245 nm is achieved in the Er3+/Ho3+/Yb3+ triply-doped fluorotellurite-germanate glass upon excitation at 980 nm. The glass not only possesses considerably low OH- absorption coefficient (0.189 cm-1), but also exhibits low phonon energy (704 cm-1). Moreover, the measured lifetime of Ho3+: 5I6 level is as high as 0.218 ms. In addition, the energy transfer rate to hydroxyl groups and quantum efficiency (η) of 5I6 level were calculated in detail by fitting the variations of lifetimes vs. the OH- concentrations. The formation ability and thermal stability of glasses have been improved by introducing GeO2 into fluorotellurite glasses. Results reveal that Er3+/Ho3+/Yb3+ triply-doped fluorotellurite-germanate glass is a potential kind of laser glass for efficient 3 µm laser.

Ho³âº/Yb³âº codoped silicate glasses for 2 µm emission performances.

This paper discuss a series of Ho³âº/Yb³âº codoped silicate glasses prepared by the melting method. 2 µm emissions of the samples are observed under the pump of 980 nm LD. The Judd-Ofelt parameters (Ω(λ)) and radiative properties are calculated and analyzed; the spontaneous transition probability can reach 78.71 s⁻¹. From the fluorescence spectra, the peak absorption and emission cross section of Ho³âº are 2.36×10⁻²¹ and 5.05×10⁻²¹ cm², respectively. In addition, we analyze the energy transfer process of Yb³âº: ²F(5/2) level to Ho³âº: 5I6 level. Considering the luminance properties and good thermal property, we indicate that Ho³âº/Yb³âº codoped silicate glass is a potential laser glass for the efficient 2 µm laser.

R2O3 (R = La, Y) modified erbium activated germanate glasses for mid-infrared 2.7 µm laser materials.

Er(3+) activated germanate glasses modified by La2O3 and Y2O3 with good thermal stability were prepared. 2.7 µm fluorescence was observed and corresponding radiative properties were investigated. A detailed discussion of J-O parameters has been carried out based on absorption spectra and Judd-Ofelt theory. The peak emission cross sections of La2O3 and Y2O3 modified germanate glass are (14.3 ± 0.10) × 10(-21) cm(2) and (15.4 ± 0.10) × 10(-21) cm(2), respectively. Non-radiative relaxation rate constants and energy transfer coefficients of (4)I11/2 and (4)I13/2 levels have been obtained and discussed to understand the 2.7 µm fluorescence behavior. Moreover, the energy transfer processes of (4)I11/2 and (4)I13/2 level were quantitatively analyzed according to Dexter's theory and Inokuti-Hirayama model. The theoretical calculations are in good agreement with the observed 2.7 µm fluorescence phenomena. Results demonstrate that the Y2O3 modified germanate glass, which possesses more excellent spectroscopic properties than La2O3 modified germanate glass, might be an attractive candidate for mid-infrared laser.

Quantitative Analysis of Energy Transfer and Origin of Quenching in Er(3+)/Ho(3+) Codoped Germanosilicate Glasses.

The energy transfer mechanism between Ho(3+) and Er(3+) ions has been investigated in germanosilicate glass excited by 980 nm laser diode. A rate equation model was developed to demonstrate the energy transfer from Er(3+) to Ho(3+) ions, quantitatively. Energy transfer efficiency from the Er(3+):(4)I13/2 to the Ho(3+):(5)I7 level can reach as high as 75%. Such a high efficiency was attributed to the excellent matching of the host phonon energy with the energy gap between Er(3+):(4)I13/2 and Ho(3+):(5)I7 levels. In addition, the energy transfer microparameter (CDA) from Er(3+):(4)I13/2 to Ho(3+):(5)I7 level was estimated to (4.16 ± 0.03) × 10(-40) cm(6)·s(-1) via the host-assisted spectral overlap function, coinciding with the CDA (2,88 ± 0.04) × 10(-40) cm(6)·s(-1) from decay analysis of the Er(3+):(4)I13/2 level which also indicated hopping migration-assisted energy transfer. Furthermore, the concentration quenching of Ho(3+):(5)I7 → (5)I8 transition was the dipole-dipole interaction in the diffusion-limited regime, and the quenching concentration of Ho(3+) reached 4.13 × 10(20) cm(-3).

The influence of TeO2 on thermal stability and 1.53 µm spectroscopic properties in Er(3+) doped oxyfluorite glasses.

In this work, the thermal and spectroscopic properties of Er(3+)-doped oxyfluorite glass based on AMCSBYT (AlF3-MgF2-CaF2-SrF2-BaF2-YF3-TeO2) system for different TeO2 concentrations from 6 to 21 mol% is reported. After adding a suitable content of TeO2, the thermal ability of glass improves significantly whose ΔT and S can reach to 118 °C and 4.47, respectively. The stimulated emission cross-section reaches to 7.80×10(-21) cm(2) and the fluorescence lifetime is 12.18 ms. At the same time, the bandwidth characteristics reach to 46.41×10(-21) cm(2) nm and the gain performance is 63.73×10(-21) cm(2) ms. These results show that the optical performances of this oxyfluorite glass are very well. Hence, AMCSBYT glass with superior performances might be a useful material for applications in optical amplifier around 1.53 µm.

Mid-infrared emission and Raman spectra analysis of Er(3+)-doped oxyfluorotellurite glasses.

This paper reports on the spectroscopic and structural properties in Er(3+)-doped oxyfluorotellurite glasses. The compositional variation accounts for the evolutions of Raman spectra, Judd-Ofelt parameters, radiative properties, and fluorescent emission. It is found that, when maximum phonon energy changes slightly, phonon density plays a crucial role in quenching the 2.7 µm emission generated by the Er(3+):(4)I11/2→(4)I13/2 transition. The comparative low phonon density contributes strong 2.7 µm emission intensity. The high branching ratio (18.63%) and large emission cross section (0.95×10(-20) cm(2)) demonstrate that oxyfluorotellurite glass contained with 50 mol.% TeO2 has potential application in the mid-infrared region laser.

Tunable mid-infrared luminescence from Er3+ -doped germanate glass.

Er(3+) -doped germanate glasses with superior thermal stability were prepared. Judd-Ofelt intensity parameters and important spectroscopic properties were discussed in detail. Upon 800 nm and 980 nm LD pumping, 2.7 µm fluorescence characteristics were investigated and it was found that the effective 2.7 µm emission bandwidth can reach to 101.79 nm in prepared glasses. The tunability of the 2.7 µm emission band can be realized by adjusting the Er(3+) content. Moreover, a high-emission cross-section (11.09 × 10(-21) cm(2) ), large gain bandwidth (772.30 × 10(-28) cm(3) ) and gain coefficient (6.72 cm(-1) ) were obtained in the prepared sample. Hence, Er(3+) -doped germanate glass might be a promising mid-infrared material for tunable amplifiers or lasers.

Mid-infrared fluorescence, energy transfer process and rate equation analysis in Er3+ doped germanate glass.

Er(3+) doped Y2O3 and Nb2O5 modified germanate glasses with different Er(3+) concentrations were prepared. J-O intensity parameters were computed to estimate the structural changes due to the additions of Y2O3 and Nb2O5. The main mid-infrared spectroscopic features were investigated. To shed light on the observed mid-infrared radiative behavior, 975 nm and 1.53 µm emission spectra along with their decay lifetimes were also discussed. Moreover, the energy transfer processes of (4)I11/2 and (4)I13/2 level were quantitatively analyzed. In view of the experimental lifetimes, the simplified rate equation was utilized to calculate the energy transfer upconversion processes of upper and lower laser level of 2.7 µm emission. The theoretical calculations are in good agreement with the observed 2.7 µm fluorescence phenomena. Finally, the stimulated emission and gain cross sections were calculated and the results indicate that Er(3+) doped germanate glasses have great potential for mid-infrared application.

Enhancement of 1.53 µm emission in erbium/cerium-doped germanosilicate glass pumped by common 808 nm laser diode.

Erbium-doped germanosilicate glasses with various cerium ions contents have been prepared. Optical absorption and 1.53 µm emission spectra were measured to characterize the spectroscopic performances of prepared samples. A detailed study of 1.53 µm spectroscopic properties was carried out when pumped by an 808 nm laser diode. Moreover, an energy level diagram and an energy transfer mechanism between Er3+ and Ce3+ were proposed to elucidate the enhanced 1.53 µm fluorescence. It is found that the prepared samples have optimal spectroscopic properties when the Ce3+ concentration is fixed to 0.5 mol. %. High spontaneous radiative transition probability (172.66 s(-1)), large effective emission bandwidth (74 nm), and emission cross section (9.49×10(-21) cm(2) indicate that 808 nm pumped Er3+/Ce3+ codoped germanosilicate glass might be a suitable material for a broadband optical amplifier.