Antibody signatures in hospitalized hand, foot and mouth disease patients with acute enterovirus A71 infection.

Enterovirus A71 (EV-A71) infection is a major cause of severe hand, foot and mouth disease (HFMD) in young children. The characteristics of EV-A71 neutralizing antibodies in HFMD patients are not well understood. In this study, we identified and cloned EV-A71-neutralizing antibodies by single cell RNA and B cell receptor sequencing of peripheral blood mononuclear cells. From 145 plasmablasts, we identified two IgG1 monoclonal antibodies (mAbs) and six IgM mAbs that neutralized EV-A71. Four of the IgM mAbs harbor germline variable sequences and neutralize EV-A71 potently. Two genetically similar IgM antibodies from two patients have recurrent heavy chain variable domain gene usage and similar complementarity-determining region 3 sequences. We mapped the residues of EV-A71 critical for neutralization through selection of virus variants resistant to antibody neutralization in the presence of neutralizing mAbs. The residues critical for neutralization are conserved among EV-A71 genotypes. Epitopes for the two genetically similar antibodies overlap with the SCARB2 binding site of EV-A71. We used escape variants to measure the epitope-specific antibody response in acute phase serum samples from EV-A71 infected HFMD patients. We found that these epitopes are immunogenic and contributed to the neutralizing antibody response against the virus. Our findings advance understanding of antibody response to EV-A71 infection in young children and have translational potential: the IgM mAbs could potentially be used for prevention or treatment of EV-A71 infections.

Elimination of Intragrain Defect to Enhance the Performance of FAPbI3 Perovskite Solar Cells by Ionic Liquid.

Ionic liquids have been widely used to improve the efficiency and stability of perovskite solar cells (PSCs), and are generally believed to passivate defects on the grain boundaries of perovskites. However, few studies have focused on the relevant effects of ionic liquids on intragrain defects in perovskites which have been shown to be critical for the performance of PSCs. In this work, the effect of ionic liquid 1-hexyl-3-methylimidazolium iodide (HMII) on intragrain defects of formamidinium lead iodide (FAPbI3) perovskite is investigated. Abundant {111}c intragrain planar defects in pure FAPbI3 grains are found to be significantly reduced by the addition of the ionic liquid HMII, shown by using ultra-low-dose selected area electron diffraction. As a result, longer charge carrier lifetimes, higher photoluminescence quantum yield, better charge carrier transport properties, lower Urbach energy, and current-voltage hysteresis are achieved, and the champion power conversion efficiency of 24.09% is demonstrated. These observations suggest that ionic liquids significantly improve device performance resulting from the elimination of {111}c intragrain planar defects.

Comparison of Neutralizing Antibody Response Kinetics in Patients with Hand, Foot, and Mouth Disease Caused by Coxsackievirus A16 or Enterovirus A71: A Longitudinal Cohort Study of Chinese Children, 2017-2019.

Hand, foot, and mouth disease (HFMD), which is mainly caused by coxsackievirus A16 (CVA16) or enterovirus A71 (EV-A71), poses a serious threat to children's health. However, the long-term dynamics of the neutralizing Ab (NAb) response and ideal paired-serum sampling time for serological diagnosis of CVA16-infected HFMD patients were unclear. In this study, 336 CVA16 and 253 EV-A71 PCR-positive HFMD inpatients were enrolled and provided 452 and 495 sera, respectively, for NAb detection. Random-intercept modeling with B-spline was conducted to characterize NAb response kinetics. The NAb titer of CVA16 infection patients was estimated to increase from negative (2.1, 95% confidence interval [CI]: 1.4-3.3) on the day of onset to a peak of 304.8 (95% CI: 233.4-398.3) on day 21 and then remained >64 until 26 mo after onset. However, the NAb response level of EV-A71-infected HFMD patients was much higher than that of CVA16-infected HFMD patients throughout. The geometric mean titer was significantly higher in severe EV-A71-infected patients than in mild patients, with a 2.0-fold (95% CI: 1.4-3.2) increase. When a 4-fold rise in titer was used as the criterion for serological diagnosis of CVA16 and EV-A71 infection, acute-phase serum needs to be collected at 0-5 d, and the corresponding convalescent serum should be respectively collected at 17.4 (95% CI: 9.6-27.4) and 24.4 d (95% CI: 15.3-38.3) after onset, respectively. In conclusion, both CVA16 and EV-A71 infection induce a persistent humoral immune response but have different NAb response levels and paired-serum sampling times for serological diagnosis. Clinical severity can affect the anti-EV-A71 NAb response.

[Clinical characteristics of children on prolonged mechanical ventilation due to different primary diseases]. / ä¸åŒåŽŸå‘ç— å¯¼è‡´é•¿æœŸæœºæ¢°é€šæ°”æ‚£å„¿çš„ä¸´åºŠç‰¹å¾åˆ†æž.

OBJECTIVES: To investigate the differences in clinical characteristics among children on prolonged mechanical ventilation (PMV) due to different primary diseases. METHODS: A retrospective analysis was performed on the clinical data of 59 pediatric patients requiring PMV from July 2017 to September 2022. According to the primary disease, they were divided into respiratory disease (RD) group, central nervous system (CNS) group, neuromuscular disease (NMD) group, and other disease group. The four groups were compared in terms of general information, treatment, and outcome. RESULTS: There were significant differences among the four groups in age, body weight, Pediatric Logistic Organ Dysfunction-2 (PELOD-2) score, Pediatric Risk of Mortality III (PRISM Ⅲ) score, analgesic and sedative treatment, nutrition supply, rehabilitation treatment, tracheotomy, successful ventilator weaning, and outcomes (P<0.05). Compared with the RD group, the CNS group and the other disease group had a significantly higher age and a significantly higher proportion of children receiving rehabilitation treatment, and the CNS group had a significantly higher proportion of children receiving tracheotomy (P<0.008). Compared with the other disease group, the CNS group and the NMD group had significantly lower PELOD-2 and PRISM III scores, and the CNS group had a significantly higher proportion of children with successful ventilator weaning and a significantly higher proportion of children who were improved and discharged (P<0.008). CONCLUSIONS: There are differences in clinical characteristics among children receiving PMV due to different etiologies. Most children in the RD group have a younger age, and children in the CNS group have a relatively good prognosis.

Protic Amine Carboxylic Acid Ionic Liquids Additives Regulate α-FAPbI3 Phase Transition for High Efficiency Perovskite Solar Cells.

The α-phase formamidinium lead tri-iodide (α-FAPbI3 ) has become the most promising photovoltaic absorber for perovskite solar cells (PSCs) due to its outstanding semiconductor properties and astonishing high efficiency. However, the incomplete crystallization and phase transition of α-FAPbI3 substantially undermine the performance and stability of PSCs. In this work, a series of the protic amine carboxylic acid ion liquids are introduced as the precursor additives to efficiently regulate the crystal growth and phase transition processes of α-FAPbI3 . The MA2 Pb3 I8 ·2DMSO phase is inhibited in annealing process, which remarkably optimizes the phase transition process of α-FAPbI3 . It is noted that the functional groups of carboxyl and ammonium passivate the undercoordinated lead ions, halide vacancies, and organic vacancies, eliminating the deleterious nonradiative recombination. Consequently, the small-area devices incorporated with 2% methylammonium butyrate (MAB) and 1.5% n-butylammonium formate (BAFa) in perovskite show champion efficiencies of 25.10% and 24.52%, respectively. Furthermore, the large-area modules (5 cm × 5 cm) achieve PCEs of 21.26% and 19.27% for MAB and BAFa additives, indicating the great potential for commercializing large-area PSCs.

Low-Cost Hydroxyacid Potassium Synergists as an Efficient In Situ Defect Passivator for High Performance Tin-Oxide-Based Perovskite Solar Cells.

Perovskite solar cells (PSCs) based on SnO2 electron transport layers have attracted extensive research due to their compelling photovoltaic performance. Herein, we presented an in situ passivation of SnO2 with low-cost hydroxyacid potassium synergist during deposition to optimize the interface carrier extraction and transport for high power conversion efficiency (PCE) and stabilities of PSCs. The orbital overlap of the carboxyl oxygen with the Sn atom alongwith the homogenous nano-particle deposition effectively suppresses the interfacial defects and releases the internal residual strains in the perovskite. Accordingly, a PCE of 24.91 % with a fill factor (FF) up to 0.852 is obtained for in situ passivated devices, which is one of the highest values for SnO2 -based PSCs. Moreover, the unencapsulated device maintained 80 % of its initial PCE at 80 °C over 600 h, 100 % PCE at ambient conditions for 1300 h, and 98 % after one week maximum power point tracking (MPPT) under continuous AM1.5G illumination.

Enhanced Carrier Diffusion Enables Efficient Back-Contact Perovskite Photovoltaics.

Back-contact architectures offer a promising route to improve the record efficiencies of perovskite solar cells (PSCs) by eliminating parasitic light absorption. However, the performance of back-contact PSCs is limited by inadequate carrier diffusion in perovskite. Here, we report that perovskite films with a preferred out-of-plane orientation show improved carrier dynamic properties. With the addition of guanidine thiocyanate, the films exhibit carrier lifetimes and mobilities increased by 3-5 times, leading to diffusion lengths exceeding 7 µm. The enhanced carrier diffusion results from substantial suppression of nonradiative recombination and improves charge collection. Devices using such films achieve reproducible efficiencies reaching 11.2 %, among the best performances for back-contact PSCs. Our findings demonstrate the impact of carrier dynamics on back-contact PSCs and provide the basis for a new route to high-performance back-contact perovskite optoelectronic devices at low cost.

Light-induced reversal of ion segregation in mixed-halide perovskites.

Bandgap instability due to light-induced phase segregation in mixed-halide perovskites presents a major challenge for their future commercial use. Here we demonstrate that photoinduced halide-ion segregation can be completely reversed at sufficiently high illumination intensities, enabling control of the optical bandgap of a mixed-halide perovskite single crystal by optimizing the input photogenerated carrier density. We develop a polaron-based two-dimensional lattice model that rationalizes the experimentally observed phenomena by assuming that the driving force for photoinduced halide segregation is dependent on carrier-induced strain gradients that vanish at high carrier densities. Using illumination sources with different excitation intensities, we demonstrate write-read-erase experiments showing that it is possible to store information in the form of latent images over several minutes. The ability to control the local halide-ion composition with light intensity opens opportunities for the use of mixed-halide perovskites in concentrator and tandem solar cells, as well as in high-power light-emissive devices and optical memory applications.

Microbiological profiles and antimicrobial resistance patterns of pediatric bloodstream pathogens in China, 2016-2018.

OBJECTIVES: This study aimed to investigate the microbiological profiles and antimicrobial resistance patterns of bloodstream pathogens in Chinese children. METHODS: This retrospective study was conducted at 13 tertiary hospitals in China during 2016-2018. The first bloodstream isolates of the same species from one pediatric patient < 18 years were included to this study for analysis. Antimicrobial susceptibility testing was determined based on minimum inhibitory concentrations or Kirby-Bauer disk diffusion methods according to the 2018 Clinical and Laboratory Standards Institute guidelines. RESULTS: Overall, 9345 nonduplicate bloodstream isolates were collected. Top 10 pathogens included Coagulase-negative staphylococcus (CoNS) (44.4%), Escherichia coli (10.2%), Klebsiella pneumoniae (5.9%), Staphylococcus aureus (5.0%), Streptococcus pneumoniae (4.9%), Pseudomonas aeruginosa(2.8%), Enterococcus faecium (2.7%), Stenotrophomonas maltophilia (2.4%), Salmonella spp. (2.3%), and Streptococcus agalactiae (2.0%). The commonest pathogens apart from CoNS in age group 0-28 days, 29 days-2 months, 3-11 months, 1-5 years, and ≥ 5 years were Escherichia coli (17.2%), Escherichia coli (14.0%), Escherichia coli (7.9%), Streptococcus pneumoniae (10.7%) ,and Staphylococcus aureus (13.6%), respectively. The overall prevalence of extended-spectrum ß-lactamases-producing Enterobacteriaceae, carbapenem-resistant Klebsiella pneumoniae, carbapenem-resistant Acinetobacter baumannii, and carbapenem-resistant Pseudomonas aeruginosa were 41.4, 28.4, 31.7, and 5.6%, respectively. The overall prevalence of methicillin-resistant Staphylococcus aureus, penicillin-resistant Streptococcus pneumoniae and vancomycin-resistant Enterococcus was 38.1, 28.3, and 0.7%, respectively. CONCLUSIONS: The major bacterial pathogens have differences in different age groups, ward types, and regions in Chinese children, and the commonest causing microorganism was the Escherichia coli, especially in neonates and infants. High prevalence of important resistant phenotypes is of a serious concern.

Downregulation of CDC20 suppressed cell proliferation, induced apoptosis, triggered cell cycle arrest in osteosarcoma cells, and enhanced chemosensitivity to cisplatin.

Osteosarcoma (OS) is a common malignant bone tumor that occurs in adolescents or children under the age of 20, which is extremely difficult to cure and has a high recurrence rate. Recent studies showed that cell division cycle 20 (CDC20) overexpression is associated with poor prognosis in patients with osteosarcoma. However, the function of CDC20 in osteosarcoma has not been investigated clearly. In this study, we aim to explore the role of CDC20 in two independent human OS cell lines' biological phenotype and chemotherapy sensitivity. We applied multiple approaches to measure cell growth, cell cycle, and apoptosis with or without deregulation or overexpression of CDC20. We found that the downregulation of CDC20 by siRNA or apcin suppressed cell proliferation, induced apoptosis, and triggered cell cycle arrest. Consistently, overexpression of CDC20 in normal cells promoted cell growth, inhibited apoptosis. What's more, the additional treatment with siCDC20 or Apcin achieved better anticancer effects than that of cisplatin alone. Furthermore, Bim and p21 were upregulated in OS cells following Apcin treatment. Altogether, the results of the present study demonstrated that targeting CDC20 could be useful for the treatment of OS, and might be a promising solution for the treatment of the OS with cisplatin insensitivity.

Understanding of perovskite crystal growth and film formation in scalable deposition processes.

Hybrid organic-inorganic perovskite photovoltaics (PSCs) have attracted significant attention during the past decade. Despite the stellar rise of laboratory-scale PSC devices, which have reached a certified efficiency over 25% to date, there is still a large efficiency gap when transiting from small-area devices to large-area solar modules. Efficiency losses would inevitably arise from the great challenges of homogeneous coating of large-area high quality perovskite films. To address this problem, we provide an in-depth understanding of the perovskite nucleation and crystal growth kinetics, including the LaMer and Ostwald ripening models, which advises us that fast nucleation and slow crystallization are essential factors in forming high-quality perovskite films. Based on these cognitions, a variety of thin film engineering approaches will be introduced, including the anti-solvent, gas-assisted and solvent annealing treatments, Lewis acid-base adduct incorporation, etc., which are able to regulate the nucleation and crystallization steps. Upscaling the photovoltaic devices is the following step. We summarize the currently developed scalable deposition technologies, including spray coating, slot-die coating, doctor blading, inkjet printing and vapour-assisted deposition. These are more appealing approaches for scalable fabrication of perovskite films than the spin coating method, in terms of lower material/solution waste, more homogeneous thin film coating over a large area, and better morphological control of the film. The working principles of these techniques will be provided, which direct us that the physical properties of the precursor solutions and surface characteristics/temperature of the substrate are both dominating factors influencing the film morphology. Optimization of the perovskite crystallization and film formation process will be subsequently summarized from these aspects. Additionally, we also highlight the significance of perovskite stability, as it is the last puzzle to realize the practical applications of PSCs. Recent efforts towards improving the stability of PSC devices to environmental factors are discussed in this part. In general, this review, comprising the mechanistic analysis of perovskite film formation, thin film engineering, scalable deposition technologies and device stability, provides a comprehensive overview of the current challenges and opportunities in the field of PSCs, aiming to promote the future development of cost-effective up-scale fabrication of highly efficient and ultra-stable PSCs for practical applications.

Alkali Cation Doping for Improving the Structural Stability of 2D Perovskite in 3D/2D PSCs.

3D/2D hybrid perovskite systems have been intensively investigated to improve the stability of perovskite solar cells (PSCs), whereas undesired crystallization of 2D perovskite during the film formation process could undermine the structural stability of 2D perovskite materials, which causes serious hysteresis of PSCs after aging. This issue is, however, rarely studied. The stability study for 3D/2D hybrid systems to date is all under the one-direction scan, and the lack of detailed information on the hysteresis after aging compromises the credibility of the stability results. In this work, by correlating the hysteresis of the hybrid PSCs with the 2D crystal structure, we find that the prompt 2D perovskite formation process easily induces numerous crystal imperfections and structural defects. These defects are susceptible to humidity attack and decompose the 2D perovskite to insulating long-chain cations and 3D perovskite, which hinder charge transfer or generate charge accumulation. Therefore, a large hysteresis is exhibited after aging the 3D/2D hybrid PSCs in an ambient environment, even though the reverse-scan power conversion efficiency (PCE) is found to be well-preserved. To address this issue, alkali cations, K+ and Rb+, are introduced into the 2D perovskite to exquisitely modulate the crystal formation, which gives rise to a higher crystallinity of 2D perovskite and a better film morphology with fewer defects. We achieved PCE beyond 21% due to the preferable charge transfer process and reduced nonradiative recombination losses. The structural features also bring about impressive moisture stability, which results in the corresponding PSCs retaining 93% of its initial PCE and negligible hysteresis after aging in an ambient atmosphere for 1200 h.

Pediatric Antibiotic Prescribing in China According to the 2019 World Health Organization Access, Watch, and Reserve (AWaRe) Antibiotic Categories.

OBJECTIVES: To assess clinical indication-specific antibiotic prescribing in pediatric practice in China based on the World Health Organization (WHO) Access, Watch, and Reserve (AWaRe) metrics and to detect potential problem areas. STUDY DESIGN: Pediatric prescription records on the 16th of each month during 2018 were sampled for all encounters at outpatient and emergency departments of 16 tertiary care hospitals via hospital information systems. Antibiotic prescribing patterns were analyzed across and within diagnostic conditions according to WHO AWaRe metrics and Anatomical Therapeutic Chemical (ATC) classification. RESULTS: A total of 260 001 pediatric encounters were assessed, and antibiotics were prescribed in 94 453 (36.3%). In 35 167 encounters (37.2%), at least 1 intravenous antibiotic was administered. WHO Watch group antibiotics accounted for 82.2% (n = 84 176) of all antibiotic therapies. Azithromycin (n = 15 791; 15.4%) was the most commonly prescribed antibiotic, and third-generation cephalosporins (n = 44 387; 43.3%) were the most commonly prescribed antibiotic class. In at least 66 098 encounters (70.0%), antibiotics were prescribed for respiratory tract conditions, mainly for bronchitis/bronchiolitis (n = 25 815; 27.3%), upper respiratory tract infection (n = 25 184; 26.7%), and pneumonia (n = 13 392; 14.2%). CONCLUSIONS: Overuse and misuse of WHO Watch group antibiotics for respiratory tract conditions and viral infectious diseases is common in pediatric outpatients in China. Pediatric antimicrobial stewardship should be strengthened using WHO AWaRe metrics.

3D Nitrogen-Doped Graphene Encapsulated Metallic Nickel-Iron Alloy Nanoparticles for Efficient Bifunctional Oxygen Electrocatalysis.

Invited for the cover of this issue is Liqiang Mai and co-workers at Wuhan University of Technology. The image depicts Ni3 Fe alloy nanoparticles encapsulated in N-doped graphene as an efficient bifunctional oxygen electrocatalyst toward rechargeable Zn-air batteries, which is expected to drive the electric vehicle. Read the full text of the article at 10.1002/chem.201904722.

3D Nitrogen-Doped Graphene Encapsulated Metallic Nickel-Iron Alloy Nanoparticles for Efficient Bifunctional Oxygen Electrocatalysis.

It is extremely desirable to explore high-efficient, affordable and robust oxygen electrocatalysts toward rechargeable Zn-air batteries (ZABs). A 3D porous nitrogen-doped graphene encapsulated metallic Ni3 Fe alloy nanoparticles aerogel (Ni3 Fe-GA1 ) was constructed through a facile hydrothermal assembly and calcination process. Benefiting from 3D porous configuration with great accessibility, high electrical conductivity, abundant active sites, optimal nitrogen content and strong electronic interactions at the Ni3 Fe/N-doped graphene heterointerface, the obtained aerogel showed outstanding catalytic performance toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Specifically, it exhibited an overpotential of 239 mV to attain 10 mA cm-2 for OER, simultaneously providing a positive onset potential of 0.93 V within a half-wave potential of 0.8 V for ORR. Accordingly, when employed in the aqueous ZABs, Ni3 Fe-GA1 achieved higher power density and superior reversibility than Pt/C-IrO2 catalyst, making it a potential candidate for rechargeable ZABs.

Interface modification effect on the performance of CsxFA1-xPbIyBr3-y perovskite solar cells fabricated by evaporation/spray-coating method.

In this study, high quality CsxFA1-xPbIyBr3-y perovskite thin films were successfully fabricated by an evaporation/spray-coating hybrid deposition method. In this method, CsI and PbI2 were first deposited via thermal evaporation, and then FAI/FABr mixed solution was sprayed on the CsI/PbI2 substrate to form the CsxFA1-xPbIyBr3-y film. As confirmed by x-ray diffraction, scanning electron microscopy, and atomic force microscopy, a perovskite film with full surface coverage and small surface roughness was obtained. Then, the effect of interface modification materials on the performance of perovskite solar cells (PSCs) was investigated: the devices with the [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) interlayer incorporated via vacuum evaporation deposition between SnO2 and perovskite showed remarkably higher performance than those with the C60 interlayer, which was attributed to enhanced charge extraction and reduced recombination at the SnO2/PCBM/perovskite interface. As a result, a high power conversion efficiency (PCE) of 18.21% was obtained for the 0.16 cm2 device. To the best of our knowledge, it is the highest efficiency of CsxFA1-xPbIyBr3-y based PSCs fabricated by the spray technique. Furthermore, we fabricated mini-modules with the size of 5 × 5 cm2 and achieved a PCE of 14.7%.

Controlling Homogenous Spherulitic Crystallization for High-Efficiency Planar Perovskite Solar Cells Fabricated under Ambient High-Humidity Conditions.

The influence of precursor solution properties, fabrication environment, and antisolvent properties on the microstructural evolution of perovskite films is reported. First, the impact of fabrication environment on the morphology of methyl ammonium lead iodide (MAPbI3 ) perovskite films with various Lewis-base additives is reported. Second, the influence of antisolvent properties on perovskite film microstructure is investigated using antisolvents ranging from nonpolar heptane to highly polar water. This study shows an ambient environment that accelerates crystal growth at the expense of nucleation and introduces anisotropies in crystal morphology. The use of antisolvents enhances nucleation but also influences ambient moisture interaction with the precursor solution, resulting in different crystal morphology (shape, size, dispersity) in different antisolvents. Crystal morphology, in turn, dictates film quality. A homogenous spherulitic crystallization results in pinhole-free films with similar microstructure irrespective of processing environment. This study further demonstrates propyl acetate, an environmentally benign antisolvent, which can induce spherulitic crystallization under ambient environment (52% relative humidity, 25 °C). With this, planar perovskite solar cells with ≈17.78% stabilized power conversion efficiency are achieved. Finally, a simple precipitation test and in situ crystallization imaging under an optical microscope that can enable a facile a priori screening of antisolvents is shown.

Visualizing Phase Segregation in Mixed-Halide Perovskite Single Crystals.

Mixed organolead halide perovskites (MOHPs), CH3 NH3 Pb(Brx I1-x )3 , have been shown to undergo phase segregation into iodide-rich domains under illumination, which presents a major challenge to their development for photovoltaic and light-emitting devices. Recent work suggested that phase-segregated domains are localized at crystal boundaries, driving investigations into the role of edge structure and the growth of larger crystals with reduced surface area. Herein, a method for growing large (30×30×1 µm3 ) monocrystalline MAPb(Brx I1-x )3 single crystals is presented. The direct visualization of the growth of nanocluster-like I-rich domains throughout the entire crystal revealed that grain boundaries are not required for this transformation. Narrowband fluorescence imaging and time-resolved spectroscopy provided new insight into the nature of the phase-segregated domains and the collective impact on the optoelectronic properties.

Photonics and Optoelectronics of 2D Metal-Halide Perovskites.

In the growing list of 2D semiconductors as potential successors to silicon in future devices, metal-halide perovskites have recently joined the family. Unlike other conversional 2D covalent semiconductors such as graphene, transition metal dichalcogenides, black phosphorus, etc., 2D perovskites are ionic materials, affording many distinct properties of their own, including high photoluminescence quantum efficiency, balanced large exciton binding energy and oscillator strength, and long carrier diffusion length. These unique properties make 2D perovskites potential candidates for optoelectronic and photonic devices such as solar cells, light-emitting diodes, photodetectors, nanolasers, waveguides, modulators, and so on, which represent a relatively new but exciting and rapidly expanding area of research. In this Review, the recent advances in emerging 2D metal-halide perovskites and their applications in the fields of optoelectronics and photonics are summarized and insights into the future direction of these fields are offered.