Metal nanowire-based transparent electrode for flexible and stretchable optoelectronic devices.

High-quality transparent electrodes are indispensable components of flexible optoelectronic devices as they guarantee sufficient light transparency and electrical conductivity. Compared to commercial indium tin oxide, metal nanowires are considered ideal candidates as flexible transparent electrodes (FTEs) owing to their superior optoelectronic properties, excellent mechanical flexibility, solution treatability, and higher compatibility with semiconductors. However, certain key challenges associated with material preparation and device fabrication remain for the practical application of metal nanowire-based electrodes. In this review, we discuss state-of-the-art solution-processed metal nanowire-based FTEs and their applications in flexible and stretchable optoelectronic devices. Specifically, the important properties of FTEs and a cost-benefit analysis of existing technologies are introduced, followed by a summary of the synthesis strategy, key properties, and fabrication technologies of the nanowires. Subsequently, we explore the applications of metal-nanowire-based FTEs in different optoelectronic devices including solar cells, photodetectors, and light-emitting diodes. Finally, the current status, future challenges, and emerging strategies in this field are presented.

Anti-synthetase syndrome in a child with pneumomediastinum: a case report and literature review.

BACKGROUND: Anti-synthetase syndrome (ASS) is a group of rare clinical subtypes within inflammatory myopathies, predominantly affecting adult females. Instances of critical illness associated with ASS in children are even rarer. CASE PRESENTATION: We report the case of a 7-year-old boy finally diagnosed with ASS, combined with pneumomediastinum. He presented with intermittent fever persisting for 12 days, paroxysmal cough for 11 days, chest pain, and shortness of breath for 4 days, prompting admission to our hospital. Pre-admission chest CT revealed diffuse pneumomediastinum, subcutaneous pneumatosis in the neck and bilateral chest wall, consolidation, atelectasis, and reticular nodular shadowing in both lungs, as well as pericardial effusion and bilateral pleural effusions. Laboratory tests revealed a positive result for serum MP immunoglobulin M (MP-IgM) and MP immunoglobulin G (MP-IgG). The patient was initially diagnosed with mycoplasma pneumoniae (MP) infection, and following 3 days of antibiotic treatment, the patient's tachypnea worsened. Positive results in muscle enzyme antibody tests included anti-PL-12 antibody IgG, anti-Jo-1 antibody IgG, and anti-RO-52 antibody IgG. Ultrasonography detected moderate effusions in the right shoulder, bilateral elbow, and knee joints. Corticosteroids pulse therapy was initiated on the 27th day following disease onset, and continued for 3 days, followed by sequential therapy for an additional 12 days. The child was discharged on the 43rd day, and subsequent follow-up revealed a significant improvement in consolidation and interstitial lesions in both lungs. CONCLUSIONS: ASS in children may combine with rapidly progressive interstitial lung disease (RPILD) and pneumomediastinum. It is crucial to promptly identify concurrent immunologic abnormalities during the outbreak of MP, particularly when the disease exhibits rapid progression with ineffective conventional antibiotic therapy.

Volatile Perovskite Precursor Ink Enables Window Printing of Phase-Pure FAPbI3 Perovskite Solar Cells and Modules in Ambient Atmosphere.

Despite the great success of perovskite photovoltaics in terms of device efficiency and stability using laboratory-scale spin-coating methods, the demand for high-throughput and cost-effective solutions remains unresolved and rarely reported because of the complicated nature of perovskite crystallization. In this work, we propose a stable precursor ink design strategy to control the solvent volatilization and perovskite crystallization to enable the wide speed window printing (0.3 to 18.0 m/min) of phase-pure FAPbI3 perovskite solar cells (pero-SCs) in ambient atmosphere. The FAPbI3 perovskite precursor ink uses volatile acetonitrile (ACN) as the main solvent with DMF and DMSO as coordination additives is beneficial to improve the ink stability, inhibit the coffee rings, and the complicated intermediate FAPbI3 phases, delivering high-quality pin-hole free and phase-pure FAPbI3 perovskite films with large-scale uniformity. Ultimately, small-area FAPbI3 pero-SCs (0.062 cm2 ) and large-area modules (15.64 cm2 ) achieved remarkable efficiencies of 24.32 % and 21.90 %, respectively, whereas the PCE of the devices can be maintained at 23.76 % when the printing speed increases to 18.0 m/min. Specifically, the unencapsulated device exhibits superior operational stability with T90 >1350 h. This work represents a step towards the scalable, cost-effective manufacturing of perovskite photovoltaics with both high performance and high throughput.

Iodonium Initiators: Paving the Air-free Oxidation of Spiro-OMeTAD for Efficient and Stable Perovskite Solar Cells.

To date, perovskite solar cells (pero-SCs) with doped 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD) hole transporting layers (HTLs) have shown the highest recorded power conversion efficiencies (PCEs). However, their commercialization is still impeded by poor device stability owing to the hygroscopic lithium bis(trifluoromethanesulfonyl)imide and volatile 4-tert-butylpyridine dopants as well as time-consuming oxidation in air. In this study, we explored a series of single-component iodonium initiators with strong oxidability and different electron delocalization properties to precisely manipulate the oxidation states of Spiro-OMeTAD without air assistance, and the oxidation mechanism was clearly understood. Iodine (III) in the diphenyliodonium cation (IP+ ) can accept a single electron from Spiro-OMeTAD and forms Spiro-OMeTAD⋅+ owing to its strong oxidability. Moreover, because of the coordination of the strongly delocalized TFSI- with Spiro-OMeTAD⋅+ in a stable radical complex, the resulting hole mobility was 30 times higher than that of pristine Spiro-OMeTAD. In addition, the IP-TFSI initiator facilitated the growth of a homogeneous and pinhole-free Spiro-OMeTAD film. The pero-SCs based on this oxidizing HTL showed excellent efficiencies of 25.16 % (certified: 24.85 % for 0.062-cm2 ) and 20.71 % for a 15.03-cm2 module as well as remarkable overall stability.

Seizures in children undergoing extracorporeal membrane oxygenation: a systematic review and meta-analysis.

OBJECTIVES: To investigate the incidence of seizures and short-term mortality associated with seizures in children undergoing extracorporeal membrane oxygenation (ECMO). METHODS: PubMed, Embase, and Web of Science were searched from inception to September 2021. Study quality was assessed using the Newcastle-Ottawa Scale. Random effects meta-analysis was conducted. RESULTS: Fourteen studies met the inclusion criteria for quantitative meta-analysis. The cumulative estimate of seizure incidence was 15% (95% CI: 12-17%). Studies using electroencephalography reported a higher incidence of seizures compared with those using electro-clinical criteria (19% vs. 9%, P = 0.034). Furthermore, 75% of seizures were subclinical. Children receiving extracorporeal cardiopulmonary resuscitation (ECPR) exhibited a higher incidence of seizures compared to children with respiratory and cardiac indications. Seizure incidence was higher in patients undergoing venoarterial (VA) ECMO compared with venovenous (VV) ECMO. The pooled odds ratio of mortality was 2.58 (95% CI: 2.25-2.95) in those developed seizures. CONCLUSION: The incidence of seizures in children requiring ECMO was 15% and majority of seizures were subclinical. The incidence of seizures was higher in patients receiving ECPR than in those with respiratory and cardiac indications. Seizures were more frequent in patients undergoing VA ECMO than VV ECMO. Seizures were associated with increased short-term mortality. IMPACT: The incidence of seizures in children undergoing extracorporeal membrane oxygenation (ECMO) was ~15% and majority of the seizures were subclinical. Seizures were associated with increased short-term mortality. Risk factors for seizures were extracorporeal cardiopulmonary resuscitation and venoarterial ECMO. Electroencephalography (EEG) monitoring is recommended in children undergoing ECMO and further studies on the optimal protocol for EEG monitoring are necessary.

A novel MRI feature, the cut green pepper sign, can help differentiate a suprasellar pilocytic astrocytoma from an adamantinomatous craniopharyngioma.

OBJECTIVE: There are no specific magnetic resonance imaging (MRI) features that distinguish pilocytic astrocytoma (PA) from adamantinomatous craniopharyngioma (ACP). In this study we compared the frequency of a novel enhancement characteristic on MRI (called the cut green pepper sign) in PA and ACP. METHODS: Consecutive patients with PA (n = 24) and ACP (n = 36) in the suprasellar region were included in the analysis. The cut green pepper sign was evaluated on post-contrast T1WI images independently by 2 neuroradiologists who were unaware of the pathologic diagnosis. The frequency of cut green pepper sign in PA and ACP was compared with Fisher's exact test. RESULTS: The cut green pepper sign was identified in 50% (12/24) of patients with PA, and 5.6% (2/36) with ACP. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the cut green pepper sign for diagnosing PA were 50%, 94.4%, 85.7% and 73.9%, respectively. There was a statistically significant difference in the age of patients with PA with and without the cut green pepper sign (12.3 ± 9.2 years vs. 5.5 ± 4.4 years, p = 0.035). CONCLUSION: The novel cut green pepper sign can help distinguish suprasellar PA from ACP on MRI.

Green Solvent Processable, Asymmetric Dopant-Free Hole Transport Layer Material for Efficient and Stable n-i-p Perovskite Solar Cells and Modules.

The use of dopant-free hole transport layers (HTLs) is critical in stabilizing n-i-p perovskite solar cells (pero-SCs). However, these HTL materials are often processed with toxic solvents, which is not ideal for industrial production. Upon substituting them with green solvents, a trade-off emerges between maintaining the high crystallinity of the HTL materials and ensuring high solubility in the new solvents. In this paper, we designed a novel, linear, organic small molecule, BDT-C8-3O, by introducing an asymmetric polar oligo(ethylene glycol) side chain. This method not only overcomes the solubility limitations in green solvents but also enables stacking the conjugated main chains in two patterns, which further enhances crystallinity and hole mobility. As a result, the n-i-p pero-SCs based on chlorobenzene- or green (natural compound) solvent 3-methylcyclohexanone-processed BDT-C8-3O HTL that without any dopant delivered world-recorded power conversion efficiencies of 24.11 % (certified of 23.82 %) and 23.53 %, respectively. The devices also demonstrated remarkable operational and high-temperature stabilities, maintaining over 84 % and 79.5 % of their initial efficiency for 2000 h, respectively. Encouragingly, dopant-free BDT-C8-3O HTL exhibits significant advantages in large-area fabrication, achieving state-of-the-art PCEs exceeding 20 % for 5×5 cm2 modules (active area: 15.64 cm2 ), even when processed using green solvents.

Functional Ionic Liquid Polymer Stabilizer for High-Performance Perovskite Photovoltaics.

The stability-related issues arising from the perovskite precursor inks, films, device structures and interdependence remain severely under-explored to date. Herein, we designed an ionic-liquid polymer (poly[Se-MI][BF4 ]), containing functional moieties like carbonyl (C=O), selenium (Se+ ), and tetrafluoroborate (BF4 - ) ions, to stabilize the whole device fabrication process. The C=O and Se+ can coordinate with lead and iodine (I- ) ions to stabilize lead polyhalide colloids and the compositions of the perovskite precursor inks for over two months. The Se+ anchored on grain boundaries and the defects passivated by BF4 - efficiently suppress the dissociation and migration of I- in perovskite films. Benefiting from the synergistic effects of poly[Se-MI][BF4 ], high efficiencies of 25.10 % and 20.85 % were exhibited by a 0.062-cm2 device and 15.39-cm2 module, respectively. The devices retained over 90 % of their initial efficiency under operation for 2200 h.

Realizing 17.5% Efficiency Flexible Organic Solar Cells via Atomic-Level Chemical Welding of Silver Nanowire Electrodes.

Solution processable flexible transparent electrodes (FTEs) are urgently needed to boost the efficiency and mechanical stability of flexible organic solar cells (OSCs) on a large scale. However, how to balance the optoelectronic properties and meanwhile achieve robust mechanical behavior of FTEs is still a huge challenge. Silver nanowire (AgNW) electrodes, exhibiting easily tuned optoelectronic/mechanical properties, are attracting considerable attention, but their poor contacts at the junction site of the AgNWs increase the sheet resistance and reduce mechanical stability. In this study, an ionic liquid (IL)-type reducing agent containing Cl- and a dihydroxyl group was employed to control the reduction process of silver (Ag) in AgNW-based FTEs precisely. The Cl- in the IL regulates the Ag+ concentration through the formation and dissolution of AgCl, whereas the dihydroxyl group slowly reduces the released Ag+ to form metal Ag. The reduced Ag grew in situ at the junction site of the AgNWs in a twin-crystal growth mode, facilitating an atomic-level contact between the AgNWs and the reduced Ag. This enforced atomic-level contact decreased the sheet resistance, and enhanced the mechanical stability of the FTEs. As a result, the single-junction flexible OSCs based on this chemically welded FTE achieved record power conversion efficiencies of 17.52% (active area: 0.062 cm2) and 15.82% (active area: 1.0 cm2). These flexible devices also displayed robust bending and peeling durability even under extreme test conditions.

Molecular Self-Assembly Regulated Dopant-Free Hole Transport Materials for Efficient and Stable n-i-p Perovskite Solar Cells and Scalable Modules.

Dopant-free organic hole transport materials (HTMs) remain highly desirable for stable and efficient n-i-p perovskite solar cells (pero-SCs) but rarely succeed. Here, we propose a molecular assembly strategy to overcome the limited optoelectronic properties of organic HTMs by precisely designing a linear organic small molecule BDT-DPA-F from the atomic to the molecular levels. BDT-DPA-F can assemble into a fibril network, showing an obviously improved hole mobility and decreased energy disorder. The resultant pero-SCs showed a promising efficiency of 23.12 % (certified 22.48 %), which is the highest certified value of pero-SCs with dopant-free HTMs, to date. These devices also showed a weak-dependence of efficiency on size, enabling a state-of-the-art efficiency of 22.50 % for 1-cm2 device and 20.17 % for 15.64-cm2 module. For the first time, the pero-SCs based on dopant-free HTMs realized ultralong stabilities with T80 lifetimes over 1200 h under operation or thermal aging at 85 °C.

Interfacial Dipole in Organic and Perovskite Solar Cells.

Incorporating a dipole interlayer has been one of the most crucial interfacial engineering strategies in organic and perovskite solar cells. An interfacial dipole brings steep shifts in electronic band structure across interfaces and thus effectively tunes charge carrier transport. However, the origin of the interfacial dipole and its effects on device performance are not entirely clear; they are even controversial in some cases. We devote this Perspective to identifying the electric dipole of various interlayers and correlating the interfacial dipole with device performance on the basis of classical semiconductor device theory. It is important to further consider the chemical nature of interlayers beyond the simplified model of an interfacial dipole to develop a full understanding of interfacial structure, energy bands, and device operation mechanism. Researchers are encouraged to integrate in situ and in operando characterizations with numerical simulations in future studies.

Challenges to the Stability of Active Layer Materials in Organic Solar Cells.

In the past 20 years, organic solar cells (OSCs) have made great progress in pursuing high power-conversion efficiencies, reaching the application threshold. Instead, device stability is becoming particularly important toward commercialization. There are many factors influencing the stability of OSCs, such as light, heat, humidity, oxygen, as well as device structure. Active layer materials, as the most critical functional layer in the devices, are greatly affected by these factors in terms of both efficiency and stability. Herein, it is desirable and urgent to summarize methods for obtaining active layer materials with long-term stability, mainly focusing on the chemical structure and blending morphology. Meanwhile, the corresponding degraded mechanism of OSCs is concluded and analyzed. In this outlook, challenges for developing high-performance and stable OSCs are discussed.

Multi-parameter distributed fiber sensing with higher-order optical and acoustic modes.

We propose a novel multi-parameter sensing technique based on a Brillouin optical time domain reflectometry in the elliptical-core few-mode fiber, using higher-order optical and acoustic modes. Multiple Brillouin peaks are observed for the backscattering of both the LP01 mode and LP11 mode. We characterize the temperature and strain coefficients for various optical-acoustic mode pairs. By selecting the proper combination of modes pairs, the performance of multi-parameter sensing can be optimized. Distributed sensing of temperature and strain is demonstrated over a 0.5-km elliptical-core few-mode fiber, with the discriminative uncertainty of 0.28°C and 5.81 µÎµ for temperature and strain, respectively.

Organic Solar Cell Materials toward Commercialization.

Bulk-heterojunction organic solar cells (OSCs) have received considerable attention with significant progress recently and offer a promising outlook for portable energy resources and building-integrated photovoltaics in the future. Now, it is urgent to promote the research of OSCs toward their commercialization. For the commercial application of OSCs, it is of great importance to develop high performance, high stability, and low cost photovoltaic materials. In this review, a comprehensive overview of the fundamental requirements of photoactive layer materials and interface layer materials toward commercialization is provided, mainly focusing on high performance, green manufacturing, simplifying device fabrication processes, stability, and cost issues. Furthermore, the perspectives and opportunities for this emerging field of materials science and engineering are also discussed.

Ferrocene-Based Hyperbranched Polytriazoles: Synthesis by Click Polymerization and Application as Precursors to Nanostructured Magnetoceramics.

Ferrocene-based polymers have drawn much attention in the past decades due to their unique properties and promising applications. However, the synthesis of hyperbranched polymers is still a great challenge. Here, two ferrocene-based hyperbranched polytriazoles with high molecular weights are facilely prepared by the click polymerization reactions of ferrocene-containing diazides (1) and tris(4-ethynylphenyl)amine (2) using Cu(PPh3 )3 Br as catalyst in dimethylformamide at 60 °C for 5 and 9 h in satisfactory yields of 54.0% and 52.3%. The resulting polytriazoles are soluble in common organic solvents and thermally stable, with 5% weight loss temperatures up to 307 °C. They can be used as precursors to produce nanostructured ceramics with good magnetizability by pyrolysis at elevated temperature.

Centralized Multi-Sensor Square Root Cubature Joint Probabilistic Data Association.

This paper focuses on the tracking problem of multiple targets with multiple sensors in a nonlinear cluttered environment. To avoid Jacobian matrix computation and scaling parameter adjustment, improve numerical stability, and acquire more accurate estimated results for centralized nonlinear tracking, a novel centralized multi-sensor square root cubature joint probabilistic data association algorithm (CMSCJPDA) is proposed. Firstly, the multi-sensor tracking problem is decomposed into several single-sensor multi-target tracking problems, which are sequentially processed during the estimation. Then, in each sensor, the assignment of its measurements to target tracks is accomplished on the basis of joint probabilistic data association (JPDA), and a weighted probability fusion method with square root version of a cubature Kalman filter (SRCKF) is utilized to estimate the targets' state. With the measurements in all sensors processed CMSCJPDA is derived and the global estimated state is achieved. Experimental results show that CMSCJPDA is superior to the state-of-the-art algorithms in the aspects of tracking accuracy, numerical stability, and computational cost, which provides a new idea to solve multi-sensor tracking problems.

Multifunctional Fullerene Derivative for Interface Engineering in Perovskite Solar Cells.

In perovskite based planar heterojunction solar cells, the interface between the TiO2 compact layer and the perovskite film is critical for high photovoltaic performance. The deep trap states on the TiO2 surface induce several challenging issues, such as charge recombination loss and poor stability etc. To solve the problems, we synthesized a triblock fullerene derivative (PCBB-2CN-2C8) via rational molecular design for interface engineering in the perovskite solar cells. Modifying the TiO2 surface with the compound significantly improves charge extraction from the perovskite layer. Together with its uplifted surface work function, open circuit voltage and fill factor are dramatically increased from 0.99 to 1.06 V, and from 72.2% to 79.1%, respectively, resulting in 20.7% improvement in power conversion efficiency for the best performing devices. Scrutinizing the electrical properties of this modified interfacial layer strongly suggests that PCBB-2CN-2C8 passivates the TiO2 surface and thus reduces charge recombination loss caused by the deep trap states of TiO2. The passivation effect is further proven by stability testing of the perovskite solar cells with shelf lifetime under ambient conditions improved by a factor of more than 4, from ∼40 h to ∼200 h, using PCBB-2CN-2C8 as the TiO2 modification layer. This work offers not only a promising material for cathode interface engineering, but also provides a viable approach to address the challenges of deep trap states on TiO2 surface in planar perovskite solar cells.

Supramolecular [60]fullerene liquid crystals formed by self-organized two-dimensional crystals.

Fullerene-based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self-organization and external-field-responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self-organization driven by π-π interactions to form triple-layer two-dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals.

Recent Progress in Dopant-Free and Green Solvent-Processable Organic Hole Transport Materials for Efficient and Stable Perovskite Solar Cells.

Dopant-free hole transport layers (HTLs) are crucial in enhancing perovskite solar cells (pero-SCs). Nevertheless, conventional processing of these HTL materials involves using toxic solvents, which gives rise to substantial environmental concerns and renders them unsuitable for large-scale industrial production. Consequently, there is a pressing need to develop dopant-free HTL materials processed using green solvents to facilitate the production of high-performance pero-SCs. Recently, several strategies have been developed to simultaneously improve the solubility of these materials and regulate molecular stacking for high hole mobility. In this review, a comprehensive overview of the methodologies utilized in developing dopant-free HTL materials processed from green solvents is provided. First, the study provides a brief overview of fundamental information about green solvents and Hansen solubility parameters, which can serve as a guideline for the molecular design of optimal HTL materials. Second, the intrinsic relationships between molecular structure, solubility in green solvents, molecular stacking, and device performance are discussed. Finally, conclusions and perspectives are presented along with the rational design of highly efficient, stable, and green solvent-processable dopant-free HTL materials.