Direct in Situ Fabrication of Multicolor Afterglow Carbon Dot Patterns with Transparent and Traceless Features via Laser Direct Writing.

Multicolor afterglow patterns with transparent and traceless features are important for the exploration of new functionalities and applications. Herein, we report a direct in situ patterning technique for fabricating afterglow carbon dots (CDs) based on laser direct writing (LDW) for the first time. We explore a facile step-scanning method that reduces the heat-affected zone and avoids uneven heating, thus producing a fine-resolution afterglow CD pattern with a minimum line width of 80 µm. Unlike previous LDW-induced luminescence patterns, the patterned CD films are traceless and transparent, which is mainly attributed to a uniform heat distribution and gentle temperature rise process. Interestingly, by regulating the laser parameters and CD precursors, an increased carbonization and oxidation degree of CDs could be obtained, thus enabling time-dependent, tunable afterglow colors from blue to red. In addition, we demonstrate their potential applications in the in situ fabrication of flexible and stretchable optoelectronics.

Multi-color transparent display based on perovskite quantum dots fabricated by laser-induced plasma etching.

Display technology is being revolutionized by cutting-edge transparent displays that can provide visual information on the screen while allowing the surrounding environment to be visible. In this report, a new method is proposed for patterning displays based on perovskite quantum dots (PQDs) on glass surfaces. A glass substrate with a polyvinylidene fluoride (PVDF) constraint layer is patterned using laser-induced plasma etching, and then a PQDs film is spin-coated on the etched sample. The PQDs pattern on the glass substrate is obtained after peeling off the PVDF constraint layer. The thickness of the film is obtained by carrying out simulations. The plasma output from different metal targets is recorded and analyzed to select the most suitable parameters and materials for improvement of the patterning accuracy. The transparent pattern display of PQDs is realized with an accuracy of 10-20 µm and a burial depth of about 1 µm. This method allows PQDs to be encapsulated under the substrate surface, which decreases the susceptibility of environmental impact. Additionally, encapsulation prevents the quantum dots from leaking out and causing environmental pollution. The proposed method has potential in the design of transparent displays and anti-counterfeiting applications.

Serum Exosomal MicroRNA-186-5p Positively Correlates with Lipid Indexes, Coronary Stenosis Degree, and Major Adverse Cardiovascular Events in Coronary Heart Disease.

Our previous study finds that exosomal microRNA (miR)-186-5p promotes viability and invasion of vascular smooth muscle cells to accelerate atherosclerosis via inactivating phosphoinositide 3 kinase/protein kinase B/mammalian target of rapamycin pathway. Subsequently, this study aimed to identify the linkage of serum exosomal miR-186-5p with clinical features and major adverse cardiovascular events (MACE) in coronary heart disease (CHD) patients. Serum exosomal miR-186-5p was quantified in 175 CHD patients and 50 healthy controls (HCs) via reverse transcription quantitative polymerase chain reaction. Our study revealed that serum exosomal miR-186-5p was enhanced in CHD patients vs. HCs (P < 0.001). In CHD patients, serum exosomal miR-186-5p was positively correlated with total cholesterol (P = 0.002) and low-density lipoprotein cholesterol (P = 0.003). Elevated serum exosomal miR-186-5p was linked with increased Gensini score (P = 0.028) and stenosis degree categorized by the Gensini score (P = 0.018). Regarding MACE, the 1-year and 2-year accumulating MACE rate was 6.6% and 15.6%, respectively. Serum exosomal miR-186-5p was elevated in CHD patients with MACE vs. those without (P = 0.042). By Kaplan-Meier curves and log-rank analyses, serum exosomal miR-186-5p > 1.000 (P = 0.404) and > 1.610 (P = 0.328) was not related to accumulating MACE. While serum exosomal miR-186-5p > 3.390 exhibited a correlative trend with increased accumulating MACE, but not achieving statistical significance (P = 0.071). The 1-year and 2-year accumulating MACE rate of patients with serum exosomal miR-186-5p > 3.390 was 11.5% and 21.5%, respectively; while the rate was 3.3% and 11.5% in patients with serum exosomal miR-186-5p ≤ 3.390, accordingly. Conclusively, serum exosomal miR-186-5p positively associates with lipid level, coronary stenosis degree, and the risk of MACE in CHD patients.

Suppressing Nonradiative Recombination by Electron-Donating Substituents in 2D Conjugated Triphenylamine Polymers toward Efficient Perovskite Optoelectronics.

Highly efficient perovskite optoelectronics (POEs) have been limited by nonradiative recombination. We report a strategy to inhibit the nonradiative recombination of 2D triphenylamine polymers in the hole transport layer (HTL) via introducing electron-donating groups to enhance the conjugation effect and electron cloud density. The conjugated systems with electron-donating groups present smaller energy level oscillation compared to the ones with electron-absorbing groups, as confirmed by nonadiabatic molecular dynamics (NAMD) calculation. Further study reveals that the introduction of low-frequency phonons in the electron-donating group systems shortens the nonadiabatic coupling and inhibits the nonradiative recombination. Such electron-donating groups can decrease the valence band maximum of 2D polymers and promote hole transport. Our report provides a new design strategy to suppress nonradiative recombination in HTL for application in efficient POEs.

I-III-VI Quantum Dots and Derivatives: Design, Synthesis, and Properties for Light-Emitting Diodes.

Quantum dots (QDs) are important frontier luminescent materials for future technology in flexible ultrahigh-definition display, optical information internet, and bioimaging due to their outstanding luminescence efficiency and high color purity. I-III-VI QDs and derivatives demonstrate characteristics of composition-dependent band gap, full visible light coverage, high efficiency, excellent stability, and nontoxicity, and hence are expected to be ideal candidates for environmentally friendly materials replacing traditional Cd and Pb-based QDs. In particular, their compositional flexibility is highly conducive to precise control energy band structure and microstructure. Furthermore, the quantum dot light-emitting diodes (QLEDs) exhibits superior prospects in monochrome display and white illumination. This review summarizes the recent progress of I-III-VI QDs and their application in LEDs. First, the luminescence mechanism is illustrated based on their electronic-band structural characteristics. Second, focusing on the latest progress of I-III-VI QDs, the preparation mechanism, and the regulation of photophysical properties, the corresponding application progress particularly in light-emitting diodes is summarized as well. Finally, we provide perspectives on the overall current status and challenges propose performance improvement strategies in promoting the evolution of QDs and QLEDs, indicating the future directions in this field.

Artificial Light-Harvesting System Based on Zinc Porphyrin and Benzimidazole: Construction, Resonance Energy Transfer, and Amplification Strategy for Electrochemiluminescence.

Constructing robust and efficient luminophores is of significant importance in the development of electrochemiluminescence (ECL) amplification strategies. Inspired by the resonance energy transfer in natural light-harvesting systems, we propose a novel ECL amplification system based on ECL resonance energy transfer (ECL-RET), which integrates two luminophores, benzimidazole (BIM) and zinc(II) tetrakis(4-carboxyphenyl)porphine (ZnTCPP), into one framework. Through disassembling and reconstruction processes, numerous BIM surround ZnTCPP in the constructed ZIF-9-ZnTCPP. Combined with the overlapped spectra between the emission of BIM and the absorption of ZnTCPP, the energy of multiple BIM (donor) can be concentrated to a single ZnTCPP (acceptor) to amplify the ECL emission of the acceptor. This work provides a convenient way to design an efficient ECL-RET system, which initiates a brand-new chapter in the development of ECL amplification strategies.

Homogeneous Bridging Induces Compact and Scalable Perovskite Thick Films for X-Ray Flat-Panel Detectors.

Solution-processed organic-inorganic hybrid perovskite polycrystalline thick films have shown great potential in X-ray detection. However, the preparation of compact perovskite thick films with large area is still challenging due to the limitation of feasible ink formulation and pinholes caused by solvent volatilization. Post-treatment and hot-pressing are usually involved to improve the film quality, which is however unsuitable for subsequent integration. In this work, a homogeneous bridging strategy is developed to prepare compact perovskite films directly. A stable perovskite slurry with suitable viscosity consisting of undissolved grains and supersaturated solution is formed by adding a weak coordination solvent to the pre-synthesized microcrystalline powders. Small perovskite grains in situ grow from the saturated solution during the annealing, filling the pinholes and connecting the surrounding original grains. As a result, large-area perovskite thick film with tight grain arrangement and ultralow current drift is blade-coated to achieve X-ray imaging. The optimal device displays an impressive mobility-lifetime product of 2.2 × 10-3  cm2  V-1 and a champion ratio of sensitivity to the dark current density of 2.23 × 1011  µC Gyair -1  A-1 . This work provides a simple and effective route to prepare high-quality perovskite thick films, which is instructive for the development of perovskite-based X-ray flat-panel detectors.

Hybrid mixed-dimensional WTe2/CsPbI3perovskite heterojunction for high-performance photodetectors.

Perovskites have showed significant potential for the application in photodetectors due to their outstanding electrical and optical properties. Integrating two-dimensional (2D) materials with perovskites can make full use of the high carrier mobility of 2D materials and strong light absorption of perovskite to realize excellent optoelectrical properties. Here, we demonstrate a photodetector based on the WTe2/CsPbI3heterostructure. The quenching and the shortened lifetime of photoluminescence (PL) for CsPbI3perovskite confirms the efficient charge transfer at the WTe2/CsPbI3heterojunction. After coupled with WTe2, the photoresponsivity of the CsPbI3photodetector is improved by almost two orders of magnitude due to the high-gain photogating effect. The WTe2/CsPbI3heterojunction photodetector reveals a large responsivity of 1157 A W-1and a high detectivity of 2.1 × 1013Jones. The results pave the way for the development of high-performance optoelectronic devices based on 2D materials/perovskite heterojunctions.

Machine learning and density functional theory simulation of the electronic structural properties for novel quaternary semiconductors.

In order to accelerate the application of quaternary optoelectronic materials in the field of luminescence, it is crucial to develop new quaternary semiconductor materials with excellent properties. However, faced with vast alternative quaternary semiconductors, traditional trial-and-error methods tend to be laborious and inefficient. Here, we combined machine learning (ML) with density functional theory (DFT) calculation to predict the bandgaps of 2180 quaternary semiconductors, most of which were undeveloped but environmentally friendly. The evaluation coefficient (R2) of the model using a random forest algorithm was up to 0.93 in ML. Four novel quaternary semiconductors with direct bandgaps: Ag2InGaS4, AgZn2InS4, Ag2ZnSnS4, and AgZn2GaS4, were selected from the ML model. Then their electronic structures and optical properties were further verified and studied by DFT calculations, which demonstrated that the four quaternary semiconductors had direct bandgaps, a small effective mass, and a large exciton binding energy and Stokes shift. Our calculation could significantly speed up the discovery of novel optoelectronic semiconductors and has a certain reference value for the study of luminescent materials and devices.

2D Zn-Porphyrin-Based Co(II)-MOF with 2-Methylimidazole Sitting Axially on the Paddle-Wheel Units: An Efficient Electrochemiluminescence Bioassay for SARS-CoV-2.

High electrocatalytic activity with tunable luminescence is crucial for the development of electrochemiluminescence (ECL) luminophores. In this study, a porphyrin-based heterobimetallic 2D metal organic framework (MOF), [(ZnTCPP)Co2(MeIm)] (1), is successfully self-assembled from the zinc(II) tetrakis(4-carboxyphenyl)porphine (ZnTCPP) linker and cobalt(II) ions in the presence of 2-methylimidazole (MeIm) by a facile one-pot reaction in methanol at room temperature. On the basis of the experimental results and the theoretical calculations, the MOF 1 contains paddle-wheel [Co2(-CO2)4] secondary building units (SBUs) axially coordinated by a MeIm ligand, which is very beneficial to the electron transfer between the Co(II) ions and oxygen. Combining the photosensitizers ZnTCPP and the electroactive [Co2(-CO2)4] SBUs, the 2D MOF 1 possesses an excellent ECL performance, and can be used as a novel ECL probe for rapid nonamplified detection of the RdRp gene of SARS-CoV-2 with an extremely low limit of detection (≈30 aM).

Interfacial electronic properties of metal/CsSnBr3heterojunctions.

All-inorganic lead-free perovskite CsSnBr3, has been proved good stability and optoelectronic properties in theory and experiment. However, the interfacial electronic properties of metal/CsSnBr3are still unclear in electronic devices. Herein, we systematically investigate the interfacial properties of metal electrodes (Al, Ag and Au) and CsSnBr3with different atomic terminals (SnBr2-T and CsBr-T) through the first-principles calculation. SnBr2-T and CsBr-T have various contact types and Schottky barriers due to their different interaction strengths with metals. In particular, the moderate interlayer coupling strength with Al leads to the ultra-low Schottky barrier and tunneling barrier, which makes Al possess the best contact performance among the studied metals. Furthermore, the external electric field can be effective in regulating the Schottky barrier and realizing the Ohmic contact. These findings provide useful guidance for the design of perovskite-based nanoelectronic devices with high performance.

Engineering Self-Reconstruction via Flexible Components in Layered Double Hydroxides for Superior-Evolving Performance.

Most transition metal-based catalysts for electrocatalytic oxygen evolution reaction (OER) undergo surface reconstruction to generate real active sites favorable for high OER performance. Herein, how to use self-reconstruction as an efficient strategy to develop novel and robust OER catalysts by designing pre-catalysts with flexible components susceptible to OER conditions is proposed. The NiFe-based layered double hydroxides (LDHs) intercalated with resoluble molybdate (MoO4 2- ) anions in interlayers are constructed and then demonstrated to achieve complete electrochemical self-reconstruction (ECSR) into active NiFe-oxyhydroxides (NiFeOOH) beneficial to alkaline OER. Various ex situ and in situ techniques are used to capture structural evolution process including fast dissolution of MoO4 2- and deep reconstruction to NiFeOOH upon simultaneous hydroxyl invasion and electro-oxidation. The obtained NiFeOOH exhibits an excellent OER performance with an overpotential of only 268 mV at 50 mA cm-1 and robust durability over 45 h, much superior to NiFe-LDH and commercial IrO2 benchmark. This work suggests that the ECSR engineering in component-flexible precursors is a promising strategy to develop highly active OER catalysts for energy conversion.

Advanced Devices for Tumor Diagnosis and Therapy.

At present, tumor diagnosis is performed using common procedures, which are slow, costly, and still presenting difficulties in diagnosing tumors at their early stage. Tumor therapeutic methods also mainly rely on large-scale equipment or non-intelligent treatment approaches. Thus, an early and accurate tumor diagnosis and personalized treatment may represent the best treatment option for a successful result, and the efforts in finding them are still in progress and mainly focusing on non-destructive, integrated, and multiple technologies. These objectives can be achieved with the development of advanced devices and smart technology that represent the topic of the current investigations. Therefore, this review summarizes the progress in tumor diagnosis and therapy and briefly explains the advantages and disadvantages of the described microdevices, finally proposing advanced micro smart devices as the future development trend for tumor diagnosis and therapy.

Polarization improvement of CsPbClBr2 quantum dot film by laser direct writing technology.

Inorganic halogen perovskite quantum dots not only have high fluorescence quantum efficiency, but also can emit polarized light in solution or thin film. These excellent performances make perovskite quantum dots promising to be used in next-generation displays. In this study, we develop laser direct writing technology to improve the emitted light polarization of CsPbClBr2 quantum dot film. Without using an additional polarizer, we prove that the polarization degree is maximumly increased by about 56%, and the reasons are analyzed from three perspectives: laser scanning space, laser power, and film thickness. In addition, the lifetime of the fluorescence is also greatly improved after laser treatment. The results we obtain provide the possibility for production of a new generation of displays.

Diverse and abundant arbuscular mycorrhizal fungi in ecological floating beds used to treat eutrophic water.

An increasing number of investigations have shown the universal existence of arbuscular mycorrhizal fungi (AMF) in aquatic ecosystems. However, little is known about the accurate distribution and function of AMF inhabiting aquatic ecosystems, especially ecological floating beds (EFBs), which are constructed for the remediation of polluted water bodies. In this study, we collected root samples of Canna generalis, Cyperus alternifolius, and Eichhornia crassipes from three EFBs on two eutrophic lakes in Wuhan, China. We aimed to investigate the resources and distribution of AMF in EFBs using Illumina Mi-seq technology. A total of 229 operational taxonomic units (OTUs) and 21 taxa from 348,799 Glomeromycota sequences were detected. Glomus and Acaulospora were the most dominant and second most dominant genera of AMF in the three EFBs, respectively. Different aquatic plant species showed varying degrees of AMF colonization (3.83-71%), diversity (6-103 OTUs, 3-15 virtual taxa), and abundance (14-57,551 sequences). Low AMF abundance, but relatively high AMF diversity, was found in C. alternifolius, which is usually considered non-mycorrhizal. This finding indicated the high accuracy of Illumina sequencing. Our results also revealed a lognormal species abundance distribution that was observed across AMF taxa in the three plant species. The AMF community composition was closely related to nitrogen and phosphorus contents. Overall, our data show that EFBs harbor diverse and abundant AMF communities. Additionally, the AMF community composition is closely related to the water quality of eutrophic lakes treated by the EFBs, indicating the potential application of AMF in plant-based bioremediation of wastewater. KEYPOINTS: • Aquatic plants in EFBs harbor diverse (229 OTUs) and abundant (348,799 sequences) AMF. • Different plant species host different taxa of AMF. Cyperaceae, originally considered non-mycorrhizal, may in fact be a variable mycorrhizal plant family. • The AMF community composition in EFBs is closely related to nutrient concentrations (nitrogen and phosphorus).

Advances of 2D bismuth in energy sciences.

Since graphene has been successfully exfoliated, two-dimensional (2D) materials constitute a vibrant research field and open vast perspectives in high-performance applications. Among them, bismuthene and 2D bismuth (Bi) are unique with superior properties to fabricate state-of-the-art energy saving, storage and conversion devices. The largest experimentally determined bulk gap, even larger than those of stanene and antimonene, allows 2D Bi to be the most promising candidate to construct room-temperature topological insulators. Moreover, 2D Bi exhibits cyclability for high-performance sodium-ion batteries, and the enlarged surface together with the good electrochemical activity renders it an efficient electrocatalyst for energy conversion. Also, the air-stability of 2D Bi is better than that of silicene, germanene, phosphorene and arsenene, which could enable more practical applications. This review aims to thoroughly explore the fundamentals of 2D Bi and its improved fabrication methods, in order to further bridge gaps between theoretical predictions and experimental achievements in its energy-related applications. We begin with an introduction of the status of 2D Bi in the 2D-material family, which is followed by descriptions of its intrinsic properties along with various fabrication methods. The vast implications of 2D Bi for high-performance devices can be envisioned to add a new pillar in energy sciences. In addition, in the context of recent pioneering studies on moiré superlattices of other 2D materials, we hope that the improved manipulation techniques of bismuthene, along with its unique properties, might even enable 2D Bi to play an important role in future energy-related twistronics.

Overcoming the Anisotropic Growth Limitations of Free-Standing Single-Crystal Halide Perovskite Films.

It is extremely challenging to grow single-crystal halide perovskite films (SCHPFs) with not only desired transport properties but also large lateral size with much thinner thickness. Here, we report the growth of freestanding single crystal CsPbBr3 SCHPFs with thickness less than 100 nm and a lateral size close to centimeter for the first time. A new model for growth kinetics (Ψ=Aexp[-(EA -Es )/(kB T)]) is proposed to address the surface energy and temperature effect on the growth rate of ultrathin CsPbBr3 single-crystal film. The experimental results and DFT calculations both demonstrated that the surfactant plays a critical role in modifying the surface energy and achieving anisotropic growth. This work opens new opportunities for high-quality SCHPFs with large lateral size and controllable thickness that may find wide applications for optoelectronic devices.

Enhanced Electrochemiluminescence of Porphyrin-Based Metal-Organic Frameworks Controlled via Coordination Modulation.

Precise control over the composition, morphology, and size of porphyrin-based metal-organic frameworks is challenging, but the extension of these hybrid materials will enable the creation of novel electrochemiluminescence (ECL) emitters. The coordination of various entities is made from Zn2+ ions and meso-tetra(4-carboxyphenyl)porphine (TCPP), modulated by both solvent and bathophenanthrolinedisulfonic acid disodium salt (BPS) as capping agent, resulting in limited crystal growth of Zn-TCPP in DMF/H2O (v/v, 1:1) and the formation of nanoscale TCPP-Zn-BPS. The role of BPS is also evaluated using Zn-TCPP and BPS-Zn-TCPP as controls, prepared in the absence of BPS and different coordinating sequences of ligands, respectively. The newly obtained TCPP-Zn-BPS exhibits a variety of different morphologies, as well as spectral and optoelectronic properties. The ECL behavior of TCPP-Zn-BPS is investigated by using H2O2 as co-reactant. The amplification of ECL is further studied by ECL spectroscopies and cyclic voltammetry, with the corresponding mechanism proposed.

Postsynthesis Ligand Exchange Induced Porphyrin Hybrid Crystalloid Reconstruction for Self-Enhanced Electrochemiluminescence.

In traditional coreactant electrochemiluminescence (ECL), the efficiency of the coreactant catalyzed into an active intermediate is one of the dominant factors restricting the luminous intensity. In this work, Co-2-MI-ZnTCPP is designed as a composite material integrating coreaction accelerator (Co-N) and luminophore. Through the catalytic effect of Co-N structures on hydrogen peroxide, the in situ generation and accumulation of active intermediates are achieved, which will react with porphyrin anion radical, thereby bringing out self-enhanced ECL. By adjusting the scanning potential range, the ECL mechanism is thoroughly studied and the contribution of each potential window to the luminescence is obtained. This work provides inspiration for the design of integrated ECL emitters with a coreaction accelerator and luminophore, providing a new way for the construction of a self-enhanced ECL emitter.

Ultrathin Bismuth Nanosheets for Stable Na-Ion Batteries: Clarification of Structure and Phase Transition by in Situ Observation.

Bismuth has garnered tremendous interest for Na-ion batteries (NIBs) due to potentially high volumetric capacity. Yet, the bismuth upon sodiation/desodiation experiencing structure and phase transitions remains unclear, which sets a challenge for accessing nanotechnology and nanofabrication to achieve its applicability. Here, we use in situ transmission electron microscopy to disclose the structure and phase transitions of layered bismuth (few-layer bismuth nanosheets) during Na+ intercalation and alloying processes. Multistep phase transitions from Bi → NaBi → c-Na3Bi (cubic) → h-Na3Bi (hexagonal) are clearly identified, during which the Na+ migration from interlayer to in-plane evokes the structure transition from ABCABC stacking type of c-Na3Bi to ABABAB stacking type of h-Na3Bi. It is found that the metastable c-Na3Bi devotes to buffer the dramatic structure changes from thermodynamic stable h-Na3Bi, which unveils the origin of volume expansion for bismuth and has important consequences for 2D in-plane structure. As the lateral ductility can efficiently alleviate the in-plane mechanical strain caused by the Na+ migration, the few-layer bismuth nanosheet exhibits a potential cyclability for NIBs. Our findings will encourage more attention to bismuthene as a novel anode material for secondary batteries.