Anion-π interactions suppress phase impurities in FAPbI3 solar cells.

Achieving both high efficiency and long-term stability is the key to the commercialization of perovskite solar cells (PSCs)1,2. However, the diversity of perovskite (ABX3) compositions and phases makes it challenging to fabricate high-quality films3-5. Perovskite formation relies on the reaction between AX and BX2, whereas most conventional methods for film-growth regulation are based solely on the interaction with the BX2 component. Herein, we demonstrate an alternative approach to modulate reaction kinetics by anion-π interaction between AX and hexafluorobenzene (HFB). Notably, these two approaches are independent but work together to establish 'dual-site regulation', which achieves a delicate control over the reaction between AX and BX2 without unwanted intermediates. The resultant formamidinium lead halides (FAPbI3) films exhibit fewer defects, redshifted absorption and high phase purity without detectable nanoscale δ phase. Consequently, we achieved PSCs with power conversion efficiency (PCE) up to 26.07% for a 0.08-cm2 device (25.8% certified) and 24.63% for a 1-cm2 device. The device also kept 94% of its initial PCE after maximum power point (MPP) tracking for 1,258 h under full-spectrum AM 1.5 G sunlight at 50 ± 5 °C. This method expands the range of chemical interactions that occur in perovskite precursors by exploring anion-π interactions and highlights the importance of the AX component as a new and effective working site to improved photovoltaic devices with high quality and phase purity.

Supraglottic Jet Oxygenation and Ventilation to Minimize Hypoxia in Patients Receiving Flexible Bronchoscopy Under Deep Sedation: A 3-Arm Randomized Controlled Trial.

BACKGROUND: Hypoxia often occurs due to shared airway and anesthetic sedation-induced hypoventilation in patients receiving flexible bronchoscopy (FB) under deep sedation. Previous evidence has shown that supraglottic jet oxygenation and ventilation (SJOV) via Wei nasal jet tube (WNJ) reduces the incidence of hypoxia during FB. This study aimed to investigate the extent to which SJOV via WNJ could decrease the incidence of hypoxia in patients under deep sedation as compared to oxygen supplementation via WNJ alone or nasal catheter (NC) for oxygen supplementation during FB. METHODS: This was a single-center 3-arm randomized controlled trial (RCT). Adult patients scheduled to undergo FB were randomly assigned to 3 groups: NC (oxygen supplementation via NC), low-pressure low-flow (LPLF) (low-pressure oxygen supplementation via WNJ alone), or SJOV (high-pressure oxygen supplementation via WNJ). The primary outcome was hypoxia (defined as peripheral saturation of oxygen [Sp o2 ] <90% lasting more than 5 seconds) during FB. Secondary outcomes included subclinical respiratory depression or severe hypoxia, and rescue interventions specifically performed for hypoxia treatment. Other evaluated outcomes were sore throat, xerostomia, nasal bleeding, and SJOV-related barotraumatic events. RESULTS: One hundred and thirty-two randomized patients were included in 3 interventions (n = 44 in each), and all were included in the final analysis under intention to treat. Hypoxia occurred in 4 of 44 patients (9.1%) allocated to SJOV, compared to 38 of 44 patients (86%) allocated to NC, with a relative risk (RR) for hypoxia, 0.11; 98% confidence interval (CI), 0.02-0.51; P < .001; or to 27 of 44 patients (61%) allocated to LPLF, with RR for hypoxia, 0.15; 95% CI, 0.04-0.61; P < .001, respectively. The percentage of subclinical respiratory depression was also significantly diminished in patients with SJOV (39%) compared with patients with NC (100%) or patients with LPLF (96%), both P < .001. In SJOV, no severe hypoxia event occurred. More remedial interventions for hypoxia were needed in the patients with NC. Higher risk of xerostomia was observed in patients with SJOV. No severe adverse event was observed throughout the study. CONCLUSIONS: SJOV via WNJ effectively reduces the incidence of hypoxia during FB under deep sedation.

Melatonin Alleviates Acute Respiratory Distress Syndrome by Inhibiting Alveolar Macrophage NLRP3 Inflammasomes Through the ROS/HIF-1α/GLUT1 Pathway.

Sepsis-induced acute respiratory distress syndrome (ARDS) is a devastating clinically severe respiratory disorder, and no effective therapy is available. Melatonin (MEL), an endogenous neurohormone, has shown great promise in alleviating sepsis-induced ARDS, but the underlying molecular mechanism remains unclear. Using a lipopolysaccharide (LPS)-treated mouse alveolar macrophage cell line (MH-S) model, we found that MEL significantly inhibited NOD-like receptor protein 3 (NLRP3) inflammasome activation in LPS-treated macrophages, whereas this inhibitory effect of MEL was weakened in MH-S cells transfected with glucose transporter 1 (GLUT1) overexpressing lentivirus. Further experiments showed that MEL downregulated GLUT1 via inhibition of hypoxia-inducible factor 1 (HIF-1α). Notably, hydrogen peroxide (H2O2), a donor of reactive oxygen species (ROS), significantly increased the level of intracellular ROS and inhibited the regulatory effect of MEL on the HIF-1α/GLUT1 pathway. Interestingly, the protective effect of MEL was attenuated after the knockdown of melatonin receptor 1A (MT1) in MH-S cells. We also confirmed in vivo that MEL effectively downregulated the HIF-1α/GLUT1/NLRP3 pathway in the lung tissue of LPS-treated mice, as well as significantly ameliorated LPS-induced lung injury and improved survival in mice. Collectively, these findings revealed that MEL regulates the activation of the ROS/HIF-1α/GLUT1/NLRP3 pathway in alveolar macrophages via the MT1 receptor, further alleviating sepsis-induced ARDS.

Research trends in ferroptosis since the origin of the concept: A bibliometric analysis.

Ferroptosis is a newly characterized form of regulated cell death. This bibliometric analysis identified the scientific output, leading institutions and research teams, current research hotspots and trends in research on ferroptosis since the origin of the concept. We searched the Science Citation Index Expanded of Web of Science Core Collection for papers on ferroptosis up to 3 June 2022. The acquired data were analysed and visualized by Bibliometrix package and VOSviewer. The study ultimately included 3511 relevant papers, and annual production in this field has grown rapidly in recent years. Institutions and scholars from China contributed the most work, but the impact of their research was much less than that of the United States. Prof. Brent R. Stockwell's team from Columbia University in the United States has a very strong academic influence in the field. Front Cell Dev Biol published the most papers in the field of ferroptosis. As the keywords of the papers in this field changed from the most numerous 'oxidative stress', 'cell-death', 'iron', 'expression', and 'lipid-peroxidation', to 'prognosis', 'immunotherapy', 'progression', 'tumour microenvironment', and 'colorectal cancer', the hotspot of ferroptosis research is gradually shifting from basic research to clinical translational research. The mechanism of tumour formation and treatment will become the frontier in the field of ferroptosis research in the future.

Chemical approaches for electronic doping in photovoltaic materials beyond crystalline silicon.

Electronic doping is applied to tailor the electrical and optoelectronic properties of semiconductors, which have been widely adopted in information and clean energy technologies, like integrated circuit fabrication and PVs. Though this concept has prevailed in conventional PVs, it has achieved limited success in the new-generation PV materials, particularly in halide perovskites, owing to their soft lattice nature and self-compensation by intrinsic defects. In this review, we summarize the evolution of the theoretical understanding and strategies of electronic doping from Si-based photovoltaics to thin-film technologies, e.g., GaAs, CdTe and Cu(In,Ga)Se2, and also cover the emerging PVs including halide perovskites and organic solar cells. We focus on the chemical approaches to electronic doping, emphasizing various chemical interactions/bonding throughout materials synthesis/modification to device fabrication/operation. Furthermore, we propose new classifications and models of electronic doping based on the physical and chemical properties of dopants, in the context of solid-state chemistry, which inspires further development of optoelectronics based on perovskites and other hybrid materials. Finally, we outline the effects of electronic doping in semiconducting materials and highlight the challenges that need to be overcome for reliable and controllable doping.

Tungstate-mediated In-situ Passivation of Grain Boundary Grooves in Perovskite Solar Cells.

Possessed with advantageous optoelectronic properties, perovskites have boosted the rapid development of solution-processed solar cells. The performance of perovskite solar cells (PSCs) is significantly weakened by the carrier loss at grain boundary grooves (GBGs); however, it receives limited attention and there lacks effective approach to solve this issue. Herein, for the first time, we constructed the tungstate/perovskite heterointerface via a "two step" in situ reaction approach that provides effective defect passivation and ensures efficient carrier dynamics at the GBGs. The exposed perovskite at grain boundaries is converted to wide-band-gap PbWO4 via an in-situ reaction between Pb2+ and tungstate ions, which passivate defects due to the strong ionic bonding. Moreover, recombination loss is further suppressed via the heterointerface energetics modification based on an additional transformation from PbWO4 to CaWO4 . PSCs based on this groove modification strategy showed good universality in both normal and inverted structure, with an improved efficiency of 23.25 % in the n-i-p device and 23.33 % in the p-i-n device. Stable power output of the modified device could maintain 91.7 % after around 1100 h, and the device efficiency could retain 92.5 % after aging in air for around 2110 h, and 93.1 % after aging at 85 °C in N2 for 972 h.

Reducing Energy Disorder in Perovskite Solar Cells by Chelation.

In inverted perovskite solar cells (PSCs), the fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is a widely used electron transport material. However, a high degree of energy disorder and inadequate passivation of PCBM limit the efficiency of devices, and severe self-aggregation and unstable morphology limit the lifespan of devices. Here, we design a series of fullerene dyads FP-Cn (n = 4, 8, 12) to replace PCBM as an electron transport layer, where [60]fullerene is linked with a terpyridine chelating group via a flexible alkyl chain of different lengths as a spacer. Among three fullerene dyads, FP-C8 shows the most enhanced molecule ordering and adhesion with the perovskite surface due to the balanced decoupling between the chelation effect from terpyridine and the self-assembly of fullerene, leading to lower energy disorder and higher morphological stability relative to PCBM. The FP-C8/C60-based devices using Cs0.05FA0.90MA0.05PbI2.85Br0.15 as a light absorber show a power conversion efficiency of 21.69%, higher than that of PCBM/C60 (20.09%), benefiting from improved electron extraction and transport as well as reduced charge recombination loss. When employing FAPbI3 as a light absorber, the FP-C8/C60-based devices exhibit an efficiency of 23.08%, which is the champion value of inverted PSCs with solution-processed fullerene derivatives. Moreover, the FP-C8/C60-based devices show better moisture and thermal stability than PCBM/C60-based devices and maintain 96% of their original efficiency after 1200 h of operation, while their counterpart PCBM/C60 maintains 60% after 670 h.

Avoiding Structural Collapse to Reduce Lead Leakage in Perovskite Photovoltaics.

Perovskite solar cells (PSCs) have become a promising candidate for the next-generation photovoltaic technologies. As an essential element for high-efficiency PSCs however, the heavy metal Pb is soluble in water, causing a serious threat to the environment and human health. Due to the weak ionic bonding in three-dimensional (3D) perovskites, drastic structure decomposition occurs when immersing the perovskite film in water, which accelerates the Pb leakage. By introducing the chemically stable Dion-Jacobson (DJ) 2D perovskite at the 3D perovskite surface, the film dissolution is significantly slowed down, which retards lead leakage. As a result, the Pb contamination is dramatically reduced under various extreme conditions. In addition, the PSCs device deliver a power conversion efficiency (PCE) of 23.6 % and retain over 95 % of their initial PCE after the maximum power point tracking for over 1100 h.

Integrated Tapping Mode Kelvin Probe Force Microscopy with Photoinduced Force Microscopy for Correlative Chemical and Surface Potential Mapping.

Kelvin probe force microscopy (KPFM) is a popular technique for mapping the surface potential at the nanoscale through measurement of the Coulombic force between an atomic force microscopy (AFM) tip and sample. The lateral resolution of conventional KPFM variants is limited to between ≈35 and 100 nm in ambient conditions due to the long-range nature of the Coulombic force. In this article, a novel way of generating the Coulombic force in tapping mode KPFM without the need for an external AC driving voltage is presented. A field-effect transistor (FET) is used to directly switch the electrical connectivity of the tip and sample on and off periodically. The resulting Coulomb force induced by Fermi level alignment of the tip and sample results in a detectable change of the cantilever oscillation at the FET-switching frequency. The resulting FET-switched KPFM delivers a spatial resolution of ≈25 nm and inherits the high operational speed of the AFM tapping mode. Moreover, the FET-switched KPFM is integrated with photoinduced force microscopy (PiFM), enabling simultaneous acquisitions of high spatial resolution chemical distributions and surface potential maps. The integrated FET-switched KPFM with PiFM is expected to facilitate characterizations of nanoscale electrical properties of photoactive materials, semiconductors, and ferroelectric materials.

Interfacial-engineering enhanced performance and stability of ZnO nanowire-based perovskite solar cells.

Perovskite solar cells (PSCs) have attracted extensive attention due to their convenient fabrication and excellent photoelectric characteristics. The highest power conversion efficiency (PCE) of over 25% has been realized. However, ZnO as electron transport layer based PSCs exhibit inferior PCE and stability because of the mismatched energy-band and undesirable interfacial recombination. Here, we introduce a thin layer of SnO2nanocrystals to construct an interfacial engineering with gradient energy band and interfacial passivation via a facile wet chemical process at a low temperature. The best PCE obtained in this study reaches 18.36%, and the stability is substantially improved and maintains a PCE of almost 100% over 500 h. The low-temperature fabrication process facilitates the future application of ZnO/SnO2-based PSCs in flexible and stretchable electronics.

Towards commercialization: the operational stability of perovskite solar cells.

Recently, perovskite solar cells (PSCs) have attracted much attention owing to their high power conversion efficiency (25.2%) and low fabrication cost. However, the short lifetime under operation is the major obstacle for their commercialization. With efforts from the entire PSC research community, significant advances have been witnessed to improve the device operational stability, and a timely summary on the progress is urgently needed. In this review, we first clarify the definition of operational stability and its significance in the context of practical use. By analyzing the mechanisms in established approaches for operational stability improvement, we summarize several effective strategies to extend device lifetime in a layer-by-layer sequence across the entire PSC. These mechanisms are discussed in the contexts of chemical reactions, photo-physical management, technological modification, etc., which may inspire future R&D for stable PSCs. Finally, emerging operational stability standards with respect to testing and reporting device operational stability are summarized and discussed, which may help reliable device stability data circulate in the research community. The main target of this review is gaining insight into the operational stability of PSCs, as well as providing useful guidance to further improve their operational lifetime by rational materials processing and device fabrication, which would finally promote the commercialization of perovskite solar cells.

Central venous catheterization site choice based on anatomical landmark technique: a systematic review and meta-analysis.

BACKGROUND: Internal jugular vein catheterization (IJVC) and subclavian vein catheterization (SCVC) have been the most preferred central venous catheterizations (CVC) clinically. Individual preference and institutional routine dominate the traditional CVC choice; however, it is lack of high-level evidence. We sought to provide better clinical strategy for CVC site choice based on anatomical landmark technique between IJVC and SCVC. METHODS: We systematically reviewed eligible studies from PubMed, OVID, Cochrane and ClinicalTrials.Gov till February 2020. The primary outcomes were catheterization time and overall success rate, and the secondary outcomes were the first-attempt success rate and the instant mechanical complications. Ethical problems are not applicable. RESULTS: A total of 3378 patients from 7 studies were included in the analyses. Neither difference was found on the catheterization time (SMD 95% CI: -0.095-0.124, p = 0.792), nor any difference on the overall success rate (RR = 1.017, 95% CI: 0.927-1.117, p = 0.721, I2 = 89.6%) between the 2 procedures. However, subgroup analyses showed overall success rate of IJVC was significantly lower than that of SCVC (RR = 0.906, 95% CI: 0.850-0.965, p = 0.002) in adults. The first-attempt success rate of IJVC group was higher in the adults (RR = 1.472, 95% CI: 1.004-2.156, p = 0.047). No significance was detected in arterial injury (RR = 1.137, 95% CI: 0.541-2.387, p = 0.735) and pneumothorax (RR = 0.600, 95% CI: 0.32-1.126, p = 0.112) between the two procedures. Hematoma was significantly more in IJVC group than that in SCVC group (RR = 2.824, 95% CI: 1.181-6.751, p = 0.02). CONCLUSIONS: Compared with IJVC, SCVC shows a higher overall success rate while a lower first-attempt success rate in adults, and has involved with less hematoma. PROSPERO REGISTRATION: CRD42020165444.

Anti-inflammatory protein TSG-6 secreted by bone marrow mesenchymal stem cells attenuates neuropathic pain by inhibiting the TLR2/MyD88/NF-κB signaling pathway in spinal microglia.

BACKGROUND: Neuroinflammation plays a vital role in the development and maintenance of neuropathic pain. Recent evidence has proved that bone marrow mesenchymal stem cells (BMSCs) can inhibit neuropathic pain and possess potent immunomodulatory and immunosuppressive properties via secreting a variety of bioactive molecules, such as TNF-α-stimulated gene 6 protein (TSG-6). However, it is unknown whether BMSCs exert their analgesic effect against neuropathic pain by secreting TSG-6. Therefore, the present study aimed to evaluate the analgesic effects of TSG-6 released from BMSCs on neuropathic pain induced by chronic constriction injury (CCI) in rats and explored the possible underlying mechanisms in vitro and in vivo. METHODS: BMSCs were isolated from rat bone marrow and characterized by flow cytometry and functional differentiation. One day after CCI surgery, about 5 × 106 BMSCs were intrathecally injected into spinal cerebrospinal fluid. Behavioral tests, including mechanical allodynia, thermal hyperalgesia, and motor function, were carried out at 1, 3, 5, 7, 14 days after CCI surgery. Spinal cords were processed for immunohistochemical analysis of the microglial marker Iba-1. The mRNA and protein levels of pro-inflammatory cytokines (IL-1ß, TNFα, IL-6) were detected by real-time RT-PCR and ELISA. The activation of the TLR2/MyD88/NF-κB signaling pathway was evaluated by Western blot and immunofluorescence staining. The analgesic effect of exogenous recombinant TSG-6 on CCI-induced mechanical allodynia and heat hyperalgesia was observed by behavioral tests. In the in vitro experiments, primary cultured microglia were stimulated with the TLR2 agonist Pam3CSK4, and then co-cultured with BMSCs or recombinant TSG-6. The protein expression of TLR2, MyD88, p-p65 was evaluated by Western blot. The mRNA and protein levels of IL-1ß, TNFα, IL-6 were detected by real-time RT-PCR and ELISA. BMSCs were transfected with the TSG-6-specific shRNA and then intrathecally injected into spinal cerebrospinal fluid in vivo or co-cultured with Pam3CSK4-treated primary microglia in vitro to investigate whether TSG-6 participated in the therapeutic effect of BMSCs on CCI-induced neuropathic pain and neuroinflammation. RESULTS: We found that CCI-induced mechanical allodynia and heat hyperalgesia were ameliorated by intrathecal injection of BMSCs. Moreover, intrathecal administration of BMSCs inhibited CCI-induced neuroinflammation in spinal cord tissues. The analgesic effect and anti-inflammatory property of BMSCs were attenuated when TSG-6 expression was silenced. We also found that BMSCs inhibited the activation of the TLR2/MyD88/NF-κB pathway in the ipsilateral spinal cord dorsal horn by secreting TSG-6. Meanwhile, we proved that intrathecal injection of exogenous recombinant TSG-6 effectively attenuated CCI-induced neuropathic pain. Furthermore, in vitro experiments showed that BMSCs and TSG-6 downregulated the TLR2/MyD88/NF-κB signaling and reduced the production of pro-inflammatory cytokines, such as IL-1ß, IL-6, and TNF-α, in primary microglia treated with the specific TLR2 agonist Pam3CSK4. CONCLUSIONS: The present study demonstrated a paracrine mechanism by which intrathecal injection of BMSCs targets the TLR2/MyD88/NF-κB pathway in spinal cord dorsal horn microglia to elicit neuroprotection and sustained neuropathic pain relief via TSG-6 secretion.

Positive End-Expiratory Pressure During Anesthesia for Prevention of Postoperative Pulmonary Complications: A Meta-analysis With Trial Sequential Analysis of Randomized Controlled Trials.

BACKGROUND: Whether intraoperative positive end-expiratory pressure (PEEP) can reduce the risk of postoperative pulmonary complications remains controversial. We performed a systematic review of currently available literature to investigate whether intraoperative PEEP decreases pulmonary complications in anesthetized patients undergoing surgery. METHODS: We searched PubMed, Embase, and the Cochrane Library to identify randomized controlled trials (RCTs) that compared intraoperative PEEP versus zero PEEP (ZEEP) for postoperative pulmonary complications in adults. The prespecified primary outcome was postoperative pulmonary atelectasis. RESULTS: Fourteen RCTs enrolling 1238 patients met the inclusion criteria. Meta-analysis using a random-effects model showed a decrease in postoperative atelectasis (relative risk [RR], 0.51; 95% confidence interval [CI], 0.35-0.76; trial sequential analyses [TSA]-adjusted CI, 0.10-2.55) and postoperative pneumonia (RR, 0.48; 95% CI, 0.27-0.84; TSA-adjusted CI, 0.05-4.86) in patients receiving PEEP ventilation. However, TSA showed that the cumulative Z-curve of 2 outcomes crossed the conventional boundary but did not cross the trial sequential monitoring boundary, indicating a possible false-positive result. We observed no effect of PEEP versus ZEEP ventilation on postoperative mortality (RR, 1.78; 95% CI, 0.55-5.70). CONCLUSIONS: The evidence that intraoperative PEEP reduces postoperative pulmonary complications is suggestive but too unreliable to allow definitive conclusions to be drawn.

The Role of Surface Termination in Halide Perovskites for Efficient Photocatalytic Synthesis.

Halide perovskites have received attention in the field of photocatalysis owing to their excellent optoelectronic properties. However, the semiconductor properties of halide perovskite surfaces and the influence on photocatalytic performance have not been systematically clarified. Now, the conversion of triose (such as 1,3-dihydroxyacetone (DHA)) is employed as a model reaction to explore the surface termination of MAPbI3 . By rational design of the surface termination for MAPbI3 , the production rate of butyl lactate is substantially improved to 7719 µg g-1 cat. h-1 under visible-light illumination. The MAI-terminated MAPbI3 surface governs the photocatalytic performance. Specially, MAI-terminated surface is susceptible to iodide oxidation, which thus promotes the exposure of PbII as active sites for this photocatalysis process. Moreover, MAI-termination induces a p-doping effect near the surface for MAPbI3 , which facilitates carrier transport and thus photosynthesis.

Cation Diffusion Guides Hybrid Halide Perovskite Crystallization during the Gel Stage.

Lead halide perovskites with mixed cations/anions often suffer from phase segregation, which is detrimental to device efficiency and their long-term stability. During perovskite film growth, the gel stage (in between liquid and crystalline) correlates to phase segregation, which has been rarely explored. Herein, cation diffusion kinetics are systematically investigated at the gel stage to develop a diffusion model obeying Fick's second law. Taking 2D layered perovskite as an example, theoretical and experimental results reveal the impact of diffusion coefficient, temperature, and gel duration on the film growth and phase formation. A homogenous 2D perovskite thin film was then fabricated without significant phase segregation. This in-depth understanding of gel stage and relevant cation diffusion kinetics would further guide the design and processing of halide perovskites with mixed composition to meet requirements for optoelectronic applications.

A Strategy toward New Low-Dimensional Hybrid Halide Perovskites with Anionic Spacers.

The low-dimensional halide perovskites have received enormous attention due to their unique photovoltaic and optoelectronic performances. Periodic spacers are used to inhibit the growth of 3D perovskite and fabricate a 2D counterpart with layered structure, mostly based on organic/inorganic cations. Herein, by introducing organic anions (e.g., pentanedioic acid (PDA) and hexanedioic acid (HDA) simultaneously), leaf-shaped (Cs3 Pb2 Br5 )2 (PDA-HDA) microplates with low-dimensional structure are synthesized. They also exhibit significant photoluminescence (PL) centered at 540 nm with a narrow emission peak. The synthesis of single crystals of Pb(PDA) and Pb(HDA) allows to further clarify the crystal structure of (Cs3 Pb2 Br5 )2 (PDA-HDA) perovskite and its structural evolution mechanism. Moreover, the cooperative introduction of dicarboxylic acid pairs with appropriate lengths is thermodynamically favored for the low-dimensional perovskite crystallization. The temperature-dependent PL indicates a V-shaped Stokes shift with elevated temperature that could be associated with the localization of excitons in the inorganic layers between organic dicarboxylic acid molecules. This work demonstrates low-dimensional halide perovskite with anionic spacers, which also opens up a new approach to the growth of low-dimensional organic-inorganic hybrid perovskite crystals.

Exploration of Crystallization Kinetics in Quasi Two-Dimensional Perovskite and High Performance Solar Cells.

Halide perovskites with reduced-dimensionality (e.g., quasi-2D, Q-2D) have promising stability while retaining their high performance as compared to their three-dimensional counterpart. Generally, they are obtained in (A1)2(A2)n-1PbnI3n+1 thin films by adjusting A site cations, however, the underlying crystallization kinetics mechanism is less explored. In this manuscript, we employed ternary cations halides perovskite (BA)2(MA,FA)3Pb4I13 Q-2D perovskites as an archetypal model, to understand the principles that link the crystal orientation to the carrier behavior in the polycrystalline film. We reveal that appropriate FA+ incorporation can effectively control the perovskite crystallization kinetics, which reduces nonradiative recombination centers to acquire high-quality films with a limited nonorientated phase. We further developed an in situ photoluminescence technique to observe that the Q-2D phase (n = 2, 3, 4) was formed first followed by the generation of n = ∞ perovskite in Q-2D perovskites. These findings substantially benefit the understanding of doping behavior in Q-2D perovskites crystal growth, and ultimately lead to the highest efficiency of 12.81% in (BA)2(MA,FA)3Pb4I13 Q-2D perovskites based photovoltaic devices.

High-Performance Fused Ring Electron Acceptor-Perovskite Hybrid.

We report the fused ring electron acceptor (FREA)-perovskite hybrid as a promising platform to fabricate organic-inorganic hybrid solar cells with simple preparation, high efficiency, and good stability. The FREA-perovskite hybrid films exhibit larger grain sizes and stronger crystallinity than the pristine perovskite films. Moreover, the FREA molecules can form coordination bonding with undercoordinated Pb atoms and passivate the trap states in the perovskite films. Time-resolved photoluminescence and transient absorption measurements reveal that FREA facilitates efficient electron extraction and collection. Transient photocurrent and photovoltage measurements suggest faster charge transfer and reduced charge recombination in solar cells based on FREA-perovskite hybrid films. Consequently, solar cells based on FREA-perovskite hybrid films yield a champion efficiency of 21.7% with enhanced stability, which is higher than that of the control devices based on pristine perovskite films (19.6%).

Nrf2 activation protects against intratracheal LPS induced mouse/murine acute respiratory distress syndrome by regulating macrophage polarization.

The transcription factor nuclear factor E2-related factor 2 (Nrf2) is known to control the expression of antioxidant response elements and cytoprotective genes and modulate inflammatory response, helping to ameliorate damage in many diseases. Exactly how Nrf2 regulates innate inflammatory homeostasis remains unclear. In this study, we provide in vitro and in vivo evidence that Nrf2 plays a crucial role in macrophage polarization and acute respiratory distress syndrome (ARDS). We conducted in vitro experiments using a mouse alveolar macrophage cell line as well as primary cultures of macrophages in which cells were exposed to lipopolysaccharide (LPS) or interferon-γ in order to mimic ARDS, in the presence or absence of the Nrf2 activator tert-butylhydroquinone (tBHQ). Using siRNA-mediated Nrf2 knockdown, we showed that Nrf2 inhibited the inflammatory response by promoting M2 macrophage polarization and inhibiting M1 macrophage polarization. At the same time, tBHQ activated Nrf2-mediated inhibition of the p65 nuclear factor-κB pathway and activation of peroxisome proliferator-activated receptor-γ, which play important roles in regulating macrophage polarization. We also conducted in vivo experiments in which mice were given tBHQ with or without intratracheal LPS, then their survival was monitored, lung injury was assessed using histology, and levels of pro- and anti-inflammatory cytokines were assayed in the lungs and serum. Activation of Nrf2 with tBHQ dramatically reduced LPS-induced mortality and lung injury, down-regulated pro-inflammatory mediators and up-regulated anti-inflammatory mediators. These results suggest that Nrf2 can help prevent ARDS progression by promoting M2 polarization of macrophages. Interfering with Nrf2 may be an effective strategy for reprogramming macrophage polarization in order to treat ARDS.