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In the pursuit of low‐dose flat‐panel X‐ray detection and imaging, controlling dark current is pivotal. Modulating the bandgap and resistivity of photosensitive materials is one of the methods to reduce dark current. The study introduces a novel approach by first demonstrating a non‐perovskite orthorhombic phase δ‐CsPbI2Br thick film, fabricated using an innovative elastic molecular‐assisted coating strategy. This technique results in a material with an optimized bandgap of 2.30 eV and a significantly elevated resistivity of 2.42 × 10¹⁰ Ω cm. Consequently, this leads to an ultralow dark current of 1.34 nA cm⁻2. Leveraging this advancement, the developed X‐ray detectors showcase a groundbreaking low detection limit of 53 nGyair s⁻¹, surpassing the performance of their cubic‐phase counterparts. Remarkably, the material exhibits excellent phase stability, maintaining its properties for up to 80 days. By integrating with a thin‐film transistor array, a flat‐panel X‐ray detector that delivers high‐quality 8‐bit imaging across a 64 × 64 matrix is successfully engineered. This work not only presents a transformative approach to substantially reduce dark current in low‐dose X‐ray detection but also sets a new benchmark in the field by combining enhanced imaging capability with robust long‐term stability. [ABSTRACT FROM AUTHOR]

Background: Selenium nanoparticles (SeNPs) are increasingly gaining attention due to its characteristics of low toxicity, high activity, and stability. Additionally, Bacillus licheniformis, as a probiotic, has achieved remarkable research outcomes in diverse fields such as medicine, feed processing, and pesticides, attracting widespread attention. Consequently, evaluating the activity of probiotics and SeNPs is paramount. The utilization of probiotics to synthesize SeNPs, achieving large-scale industrialization, is a current hotspot in the field of SeNPs synthesis and is currently the most promising synthetic method. To minimize production costs and maximize yield of SeNPs, this study selected agricultural by-products that are nutrient-rich, cost-effective, and readily available as culture medium components. This approach not only fulfills industrial production requirements but also mitigates the impact on downstream processes. Results: The experimental findings revealed that SeNPs synthesized by B. licheniformis F1 exhibited a spherical morphology with diameters ranging from 110 to 170 nm and demonstrating high stability. Both the secondary metabolites of B. licheniformis F1 and the synthesized SeNPs possessed significant free radical scavenging ability. To provide a more robust foundation for acquiring large quantities of SeNPs via fermentation with B. licheniformis F1, key factors were identified through single-factor experiments and response surface methodology (RSM) include a 2% seed liquid inoculum, a temperature of 37 ℃, and agitation at 180 rpm. Additionally, critical factors during the optimization process were corn powder (11.18 g/L), soybean meal (10.34 g/L), and NaCl (10.68 g/L). Upon validating the optimized conditions and culture medium, B. licheniformis F1 can synthesize nearly 100.00% SeNPs from 5 mmol/L sodium selenite. Subsequently, pilot-scale verification in a 5 L fermentor using the optimized medium resulted in a shortened fermentation time, significantly reducing production costs. Conclusion: In this study, the efficient production of SeNPs by the probiotic B. licheniformis F1 was successfully achieved, leading to a significant reduction in fermentation costs. The exploration of the practical applications of this strain holds significant potential and provides valuable guidance for facilitating the industrial-scale implementation of microbial synthesis of SeNPs. [ABSTRACT FROM AUTHOR]

Polymers undergoing controlled degradation are of significant current interest. Among the classes of degradable polymers, self-immolative polymers (SIPs) are attracting increasing attention due to their ability to completely depolymerize from end to end following the cleavage of their endcap or backbone. Their amplified responses to stimuli, along with their ability to readily tune the stimulus to which they respond by changing only their endcap, are useful features for a variety of applications. This review covers the major classes of SIPs, including poly(benzyl carbamate)s, poly(benzyl ether)s, polyphthalaldehydes, polyglyoxylates, polydisulfides, polythioesters, and their related derivatives along with their endcaps. Distinctive features of their syntheses and depolymerizations are discussed. Applications of SIPs including imaging and sensing, therapeutics, gels, micro- and nanopatterning, transient or recyclable materials, and adhesives are described. We conclude with some challenges and future perspectives for the field. [ABSTRACT FROM AUTHOR]

Acting as a growth regulator, Indole-3-acetic acid (IAA) is an important phytohormone that can be produced by several Bacillus species. However, few studies have been published on the comprehensive evaluation of the strains for practical applications and the effects of selenium species on their IAA-producing ability. The present study showed the selenite reduction strain Bacillus altitudinis LH18, which is capable of producing selenium nanoparticles (SeNPs) at a high yield in a cost-effective manner. Bio-SeNPs were systematically characterized by using DLS, zeta potential, SEM, and FTIR. The results showed that these bio-SeNPs were small in particle size, homogeneously dispersed, and highly stable. Significantly, the IAA-producing ability of strain was differently affected under different selenium species. The addition of SeNPs and sodium selenite resulted in IAA contents of 221.7 µg/mL and 91.01 µg/mL, respectively, which were 3.23 and 1.33 times higher than that of the control. This study is the first to examine the influence of various selenium species on the IAA-producing capacity of Bacillus spp., providing a theoretical foundation for the enhancement of the IAA-production potential of microorganisms. [ABSTRACT FROM AUTHOR]

The precise, controllable, and safe application of pesticides can effectively reduce pesticide consumption and minimize chemical pollution at the source. Here, a light‐responsive controlled‐release system with flexible control, precise release, easy recovery, and suitability for future pesticide application in aquatic environments is proposed. The system precisely controls the release of pesticides through a light‐responsive composite nanochannel membrane (CTC@SNM/PET) with reactive coumarin derivatives (CTC) as gating molecules. The prepared nanochannel membrane has an ultrathin thickness of 67.5 nm and well‐ordered vertical nanochannels with a uniform size of 1.9 nm, providing a prerequisite for precise molecular gating and high permeability for mass transport. CTC monomers can realize cycloaddition/cyclocracking and nanochannel closing/opening to control the release of pesticides by controlling 365/254 nm ultraviolet light irradiation. As a proof of concept, the light‐responsive controlled‐release system based on CTC@MSF/PET against Saprolegnia parasitica achieves an inhibition rate of more than 95% and reduces pesticide residues by 56.5% compared to the control group. The proposed membrane system has great application potential to easily enable remote, quantitative, timed, and positioned pesticide application, thereby reducing pesticide residues and providing a prospective approach to reducing environmental and human risks. [ABSTRACT FROM AUTHOR]

Secondary trastuzumab resistance represents an evolutionary adaptation of HER2‐positive breast cancer during anti‐HER2 treatment. Most current studies have tended to prioritize HER2 and its associated signaling pathways, often overlooking broader but seemingly less relevant cellular processes, along with their associated genetic and epigenetic mechanisms. Here, transcriptome data is not only characterized but also examined epigenomic and 3D genome architecture information in both trastuzumab‐sensitive and secondary‐resistant breast cancer cells. The findings reveal that the global metabolic reprogramming associated with trastuzumab resistance may stem from genome‐wide alterations in both histone modifications and chromatin structure. Specifically, the transcriptional activities of key genes involved in lipid metabolism appear to be regulated by variant promoter H3K27me3 and H3K4me3 modifications, as well as promoter‐enhancer interactions. These discoveries offer valuable insights into how cancer cells adapt to anti‐tumor drugs and have the potential to impact future diagnostic and treatment strategies. [ABSTRACT FROM AUTHOR]

Simple Summary: tRF-27 has been identified as upregulated in both naïve trastuzumab-resistant HER2-positive breast cancer cells and patient samples, positioning it as a potential biomarker. However, the underlying mechanisms of this upregulation remain unclear. This study proposes that the abnormal transcription of specific tRNA-Cys-GCA isodecoders in naïve trastuzumab-resistant cells might contribute to the accumulation of tRF-27. Additionally, the reduction in H3K27me3 modifications at these tRNA genes, attributed to imbalances in histone modification enzymes, appears to influence tRNA transcription alterations. Building upon these findings, our research demonstrates that the application of a demethylase inhibitor may offer a potential strategy to overcome trastuzumab resistance. tRNA-derived fragments (tRFs) play crucial roles in cancer progression. Among them, tRF-27 has been identified as a key factor in promoting naïve trastuzumab resistance in HER2-positive breast cancer. However, the origin of tRF-27 remains uncertain. In this study, we propose that the upregulated expression of specific cysteine tRNAs may lead to the increased accumulation of tRF-27 in trastuzumab-resistant JIMT1 cells. Mechanistically, the reduced inhibitory H3K27me3 modification at the promoter regions of tRF-27-related tRNA genes in JIMT1 cells, potentially resulting from decreased EZH2 and increased KDM6A activity, may be a critical factor stimulating the transcriptional activity of these tRNA genes. Our research offers fresh insights into the mechanisms underlying elevated tRF-27 levels in trastuzumab-resistant breast cancer cells and suggests potential strategies to mitigate trastuzumab resistance in clinical treatments. [ABSTRACT FROM AUTHOR]

Perovskite/silicon tandem solar cells (TSCs) have aroused much attentions in recent years. One of keys for achieving highly efficient and stable TSCs is to guarantee effective charge transfer, especially on the rough textured silicon substrate due to the poor adhesion between interlayers. Here, a 2‐fluoroisonicotinic acid (2‐FNA) additive that possesses fluorine (‐F), carboxylic acid (‐COOH), and pyridine nitrogen as functional groups in the perovskite precursor to assist the crystallization process is utilized. It shows that 2‐FNA can efficiently reduce the defects and suppress non‐radiative recombination of perovskite layers by bonding with the uncoordinated Pb2+ ions, formamidinium (FA+), and halide vacancies, leading to notably prolonged carrier lifetime. Most importantly, this found that 2‐FNA aids in the formation of better interfacial contact between the perovskite and C60 layer on top, thus enhancing the interfacial electron extraction therein, eventually leading to an increased power conversion efficiency (PCE) of 28.61% on champion perovskite/silicon TSCs from 27.08% on control counterparts. This work provides a practical route to further advance the PV performance and applicability of perovskite/silicon TSCs. [ABSTRACT FROM AUTHOR]

Cardamine violifolia, a species belonging to the Brassicaceae family, is a novel vegetable crop that is rich in glucosinolates. However, the specific glucosinolate profiles in this species remain unknown. In the present study, four parts of C. violifolia were collected including central leaves (CLs), outer leaves (OLs), petiole (P), and root (R). The highest level of total glucosinolate was observed in the R. A total of 19 glucosinolates were found in C. violifolia. The predominant glucosinolate compounds were 3-methylbutyl glucosinolate, 6-methylsulfinylhexyl glucosinolate, Indol-3-ylmethyl glucosinolate, 4-methoxyglucobrassicin, and neoglucobrassicin. A transcriptome analysis showed that 16 genes, including BCAT1, BCAT3-6, CYP79A2, CYP79B2-3, CYP83A1, CYP83B1, and SOT17-18, and nine metabolites, such as valine, tryptophan, and 1-methylpropyl glucosinolate, were enriched in the glucosinolate biosynthesis pathway. These genes may be involved in the regulation of glucosinolate accumulation among the four parts. A weighted gene co-expression analysis showed that five genes were predicted to regulate glucosinolate accumulation, including ABC transporter G family member 19, 3-ketoacyl-CoA synthase 19, and pyruvate decarboxylase 1. This study deepens our understanding of the nutrient quality of C. violifolia and provides insights into the regulatory mechanism of glucosinolate accumulation in C. violifolia. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a progressive disease, involving the progressive breakdown of cartilage, as well as changes to the synovium and bone. There are currently no disease-modifying treatments available clinically. An increasing understanding of the disease pathophysiology is leading to new potential therapeutics, but improved approaches are needed to deliver these drugs, particularly to cartilage tissue, which is avascular and contains a dense matrix of collagens and negatively charged aggrecan proteoglycans. Cationic delivery vehicles have been shown to effectively penetrate cartilage, but these studies have thus far largely focused on proteins or nanoparticles, and the effects of macromolecular architectures have not yet been explored. Described here is the synthesis of a small library of polycations composed of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-(3-aminopropyl)methacrylamide (APMA) with linear, 4-arm, or 8-arm structures and varying degrees of polymerization (DP) by reversible addition fragmentation chain-transfer (RAFT) polymerization. Uptake and retention of the polycations in bovine articular cartilage was assessed. While all polycations penetrated cartilage, uptake and retention generally increased with DP before decreasing for the highest DP. In addition, uptake and retention were higher for the linear polycations compared to the 4-arm and 8-arm polycations. In general, the polycations were well tolerated by bovine chondrocytes, but the highest DP polycations imparted greater cytotoxicity. Overall, this study reveals that linear polymer architectures may be more favorable for binding to the cartilage matrix and that the DP can be tuned to maximize uptake while minimizing cytotoxicity. [ABSTRACT FROM AUTHOR]

Highlights: The fundamental properties of electric dipoles and their specific roles in perovskite solar cells are discussed. Research progress of interfacial dipoles in perovskite solar cells is summarized. Challenges of deterministic characterization of electric dipoles and future perspectives are highlighted. Design and modification of interfaces have been the main strategies in developing perovskite solar cells (PSCs). Among the interfacial treatments, dipole molecules have emerged as a practical approach to improve the efficiency and stability of PSCs due to their unique and versatile abilities to control the interfacial properties. Despite extensive applications in conventional semiconductors, working principles and design of interfacial dipoles in the performance/stability enhancement of PSCs are lacking an insightful elucidation. In this review, we first discuss the fundamental properties of electric dipoles and the specific roles of interfacial dipoles in PSCs. Then we systematically summarize the recent progress of dipole materials in several key interfaces to achieve efficient and stable PSCs. In addition to such discussions, we also dive into reliable analytical techniques to support the characterization of interfacial dipoles in PSCs. Finally, we highlight future directions and potential avenues for research in the development of dipolar materials through tailored molecular designs. Our review sheds light on the importance of continued efforts in this exciting emerging field, which holds great potential for the development of high-performance and stable PSCs as commercially demanded. [ABSTRACT FROM AUTHOR]

The photovoltaic (PV) performance of perovskite solar cells (PSCs) has rapidly advanced in the recent years; yet, the stability issue remains one of the last‐mile challenges on the road to commercialization. Charge transport layers and their interfaces with perovskites stand for critical tuning knobs that determine the device stability of PSCs. This review focuses on the effects of modification of SnO2 electron transport layers (ETLs) on the interfacial physicochemical properties and stability of PSC devices. In detail, the intrinsic defects, surface hydroxyls, and nonuniform morphology of SnO2 will negatively impact its interfacial physicochemical properties, thus degrading the device stability of PSCs. To tackle these existing issues, three modification approaches, such as surface morphology control, surface physicochemical modifications, and surface composite‐structure design, are categorized. Lastly, future perspectives in further promoting the stability of PSCs from SnO2 ETLs are raised based on the currently unresolved issues from both material and device levels. [ABSTRACT FROM AUTHOR]

Perennial trees develop and coordinate endogenous response signaling pathways, including their crosstalk and convergence, to cope with various environmental stresses which occur simultaneously in most cases. These processes are involved in gene transcriptional regulations that depend on dynamic interactions between regulatory proteins and corresponding chromatin regions, but the mechanisms remain poorly understood in trees. In this study, we detected chromatin regulatory landscapes of poplar under abscisic acid, methyl jasmonate, salicylic acid and sodium chloride (NaCl) treatment, through integrating ATAC-seq and RNA-seq data. Our results showed that the degree of chromatin accessibility for a given gene is closely related to its expression level. However, unlike the gene expression that shows treatment-specific response patterns, changes in chromatin accessibility exhibit high similarities under these treatments. We further proposed and experimentally validated that a homologous gene copy of RESPONSIVE TO DESICCATION 26 mediates the crosstalk between jasmonic acid and NaCl signaling pathways by directly regulating the stress-responsive genes and that circadian clock-related transcription factors like REVEILLE8 play a central role in response of poplar to these treatments. Overall, our study provides a chromatin insight into the molecular mechanism of transcription regulatory networks in response to different environmental stresses and raises the key roles of the circadian clock of poplar to adapt to adverse environments. [ABSTRACT FROM AUTHOR]

Second-order correlation [ g 2 (τ) ] measurement has been utilized to characterize a nanolaser with high spontaneous emission coupling factor. Pulse excitation with low repetition rate is usually preferred for nanolasers due to its heat accumulation or photobleaching induced problem; however, introducing pulse-to-pulse timing jitter issue hinders the g 2 (τ) measurement from functioning. Here, a jitter-calibrated method is proposed by adding an extra reference time channel so that the g 2 (τ) can be calculated accurately. To verify the validity of this calibration method, the lasing threshold of a CdSe nanowire excited by a pulsed laser with a repetition rate of 1 kHz is studied. The descent of g 2 (0) to 1 coincides with the kink in light-in vs light-out curve, which confirms the effectiveness of this method. [ABSTRACT FROM AUTHOR]

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The original article can be found online at https://doi.org/10.1007/s40820-023-01131-4.Correction to: Nano-Micro Lett. (2023) 15:173https://doi.org/10.1007/s40820-023-01131-4.In the version of this Article originally published online, there was an error in the schematics of Figures 2b and 2c. These errors have now been corrected in the original article.GraphOriginal and corrected of Figures 2b and 2c.By Yinyi Ma; Jue Gong; Peng Zeng and Mingzhen LiuReported by Author; Author; Author; Author [Extracted from the article]

Layered halide perovskites (LHPs) with crystallographically 2D structures have gained increasing interest for photovoltaic applications due to their superior chemical stability and intriguing anisotropic properties, which are in contrast to their conventional 3D perovskite counterparts. The most frequently studied LHPs are Ruddlesden–Popper (RP) phases, which suffer from a carrier‐transport bottleneck due to the van der Waals gap associated with their intrinsic organic interlayer structures. To address this issue, Dion–Jacobson (DJ) and alternating‐cation‐interlayer (ACI) LHPs have rapidly emerged, which exhibit unique structural and (opto)electronic characteristics that may resemble those of the 3D counterparts owing to the eliminated or reduced van der Waals gap. Improved photophysical properties have been achieved in DJ and ACI LHPs, leading towards better photovoltaic performance. Here we provide a comprehensive discussion on the merits and promises of DJ and ACI LHPs from a chemistry perspective. Then, we review recent progress on the synthesis and tailoring of DJ and ACI LHP crystals and thin films, as well as their optoelectronic properties and photovoltaic performance. Finally, we discuss possible pathways to overcome critical challenges to realize the full potential of DJ and ACI LHPs for high‐performance solar cells and beyond. [ABSTRACT FROM AUTHOR]

Layered halide perovskites (LHPs) with crystallographically 2D structures have gained increasing interest for photovoltaic applications due to their superior chemical stability and intriguing anisotropic properties, which are in contrast to their conventional 3D perovskite counterparts. The most frequently studied LHPs are Ruddlesden–Popper (RP) phases, which suffer from a carrier‐transport bottleneck due to the van der Waals gap associated with their intrinsic organic interlayer structures. To address this issue, Dion–Jacobson (DJ) and alternating‐cation‐interlayer (ACI) LHPs have rapidly emerged, which exhibit unique structural and (opto)electronic characteristics that may resemble those of the 3D counterparts owing to the eliminated or reduced van der Waals gap. Improved photophysical properties have been achieved in DJ and ACI LHPs, leading towards better photovoltaic performance. Here we provide a comprehensive discussion on the merits and promises of DJ and ACI LHPs from a chemistry perspective. Then, we review recent progress on the synthesis and tailoring of DJ and ACI LHP crystals and thin films, as well as their optoelectronic properties and photovoltaic performance. Finally, we discuss possible pathways to overcome critical challenges to realize the full potential of DJ and ACI LHPs for high‐performance solar cells and beyond. [ABSTRACT FROM AUTHOR]

In recent years, significant efforts have been made to develop ultrafast laser source around 2- $\mu \text{m}$ wavelength. Meanwhile, the characterization of the ultrashort pulses within ultracompact footprints has been attracting growing interests. Here relying on the transverse second-harmonic generation in a single CdTe microwire, we successfully demonstrate an optical autocorrelator for femtosecond pulse characterization at 2- $\mu \text{m}$ wavelength. With 220-fs laser pulses (38 pJ/pulse) as input light, the measured pulse width after calibration is 236 fs, showing a good accuracy of this microwire autocorrelator. Due to the low-loss transmission window and high nonlinearity of CdTe in the mid-infrared (MIR) region, the microwire-based autocorrelator shows great potential for MIR applications ranging from on-chip optical communication to ultracompact laser spectroscopy. [ABSTRACT FROM AUTHOR]

In recent years, significant efforts have been made to develop ultrafast laser source around 2- $\mu \text{m}$ wavelength. Meanwhile, the characterization of the ultrashort pulses within ultracompact footprints has been attracting growing interests. Here relying on the transverse second-harmonic generation in a single CdTe microwire, we successfully demonstrate an optical autocorrelator for femtosecond pulse characterization at 2- $\mu \text{m}$ wavelength. With 220-fs laser pulses (38 pJ/pulse) as input light, the measured pulse width after calibration is 236 fs, showing a good accuracy of this microwire autocorrelator. Due to the low-loss transmission window and high nonlinearity of CdTe in the mid-infrared (MIR) region, the microwire-based autocorrelator shows great potential for MIR applications ranging from on-chip optical communication to ultracompact laser spectroscopy. [ABSTRACT FROM AUTHOR]

The soft nature of organic–inorganic halide perovskites renders their lattice particularly tunable to external stimuli such as pressure, undoubtedly offering an effective way to modify their structure for extraordinary optoelectronic properties. Here, using the methylammonium lead iodide as a representative exploratory platform, it is observed that the pressure‐driven lattice disorder can be significantly suppressed via hydrogen isotope effect, which is crucial for better optical and mechanical properties previously unattainable. By a comprehensive in situ neutron/synchrotron‐based analysis and optical characterizations, a remarkable photoluminescence (PL) enhancement by threefold is convinced in deuterated CD3ND3PbI3, which also shows much greater structural robustness with retainable PL after high peak‐pressure compression–decompression cycle. With the first‐principles calculations, an atomic level understanding of the strong correlation among the organic sublattice and lead iodide octahedral framework and structural photonics is proposed, where the less dynamic CD3ND3+ cations are vital to maintain the long‐range crystalline order through steric and Coulombic interactions. These results also show that CD3ND3PbI3‐based solar cell has comparable photovoltaic performance as CH3NH3PbI3‐based device but exhibits considerably slower degradation behavior, thus representing a paradigm by suggesting isotope‐functionalized perovskite materials for better materials‐by‐design and more stable photovoltaic application. [ABSTRACT FROM AUTHOR]

p–p orbital interaction through Mg(II) isovalent doping in methylammonium lead chloride perovskite significantly enhances the electronic properties while not affecting the optical bandgap. This chemical behaviour shows promising applications to optoelectronic devices. [ABSTRACT FROM AUTHOR]

Hybrid organic–inorganic perovskites such as methylammonium lead iodide have emerged as promising semiconductors for energy‐relevant applications. The interactions between charge carriers and lattice vibrations, giving rise to polarons, have been invoked to explain some of their extraordinary optoelectronic properties. Here, time‐resolved optical spectroscopy is performed, with off‐resonant pumping and electronic probing, to examine several representative lead iodide perovskites. The temporal oscillations of electronic bandgaps induced by coherent lattice vibrations are reported, which is attributed to antiphase octahedral rotations that dominate in the examined 3D and 2D hybrid perovskites. The off‐resonant pumping scheme permits a simplified observation of changes in the bandgap owing to the Ag vibrational mode, which is qualitatively different from vibrational modes of other symmetries and without increased complexity of photogenerated electronic charges. The work demonstrates a strong correlation between the lead–iodide octahedral framework and electronic transitions, and provides further insights into the manipulation of coherent optical phonons and related properties in hybrid perovskites on ultrafast timescales. [ABSTRACT FROM AUTHOR]

Precise diameter control is critical for many optical micro/nanofiber (MNF) applications. We demonstrate real-time MNF diameter control with improved accuracy and precision. Different from earlier works, a white light source is applied to monitor the transmittance during fiber pulling process. Terminated directly by the transmission intensity drops that indicate the cutoff of TE01 mode at particular wavelengths, we achieve diameter control accuracy and precision as high as 2nm and 3nm, respectively. The diameter control range from 360 nm to 680 nm that is demonstrated in our experiment can be extended to several tens of micron by exciting other high order modes. [ABSTRACT FROM AUTHOR]

State-of-the-art halide perovskite solar cells have bandgaps larger than 1.45 eV, which restricts their potential for realizing the Shockley-Queisser limit. Previous search for low-bandgap (1.2 to 1.4 eV) halide perovskites has resulted in several candidates, but all are hybrid organic-inorganic compositions, raising potential concern regarding device stability. Here we show the promise of an inorganic low-bandgap (1.38 eV) CsPb0.6Sn0.4I3 perovskite stabilized via interface functionalization. Device efficiency up to 13.37% is demonstrated. The device shows high operational stability under one-sun-intensity illumination, with T80 and T70 lifetimes of 653 h and 1045 h, respectively (T80 and T70 represent efficiency decays to 80% and 70% of the initial value, respectively), and long-term shelf stability under nitrogen atmosphere. Controlled exposure of the device to ambient atmosphere during a long-term (1000 h) test does not degrade the efficiency. These findings point to a promising direction for achieving low-bandgap perovskite solar cells with high stability. Current research focus on the perovskites solar cells (PSCs) is mainly limited to the lead-based ones with bandgaps above 1.5 eV. Here Hu et al. report efficient and stable inorganic tin-containing PSCs, opening doors to exploring abundant perovskite materials with bandgaps lower than 1.4 eV. [ABSTRACT FROM AUTHOR]

Background and aim: Depression is often accompanied by thoughts of self-harm, which are a strong predictor of subsequent suicide attempt and suicide death. Few empirical data are available regarding the temporal correlation between depression symptoms and suicidal ideation. We investigated the anecdotal concern that suicidal ideation may increase during a period of depression improvement. Data: Longitudinal Patient Health Questionnaire (PHQ)-9 is a questionnaire of 9 multiple-choice questions to assess the frequency of depressive symptoms within the previous two weeks. We analyzed a chronic depression treatment population’s electronic health record (EHR) data, containing 610 patients’ longitudinal PHQ-9 scores (62% age 45 and older; 68% female) within 40 weeks. Methods: The irregular and sparse EHR data were transformed into continuous trajectories using Gaussian process regression. We first estimated the correlations between the symptoms (total score of the first 8 questions; PHQ-8) and suicide ideation (9th question score; Item 9) using the cross-correlation function. We then used an artificial neural network (ANN) to discover subtypes of depression patterns from the fitted depression trajectories. In addition, we conducted a separate analysis using the unfitted raw PHQ scores to examine PHQ-8’s and Item 9’s pattern changes. Results: Results showed that the majority of patients’ PHQ-8 and Item 9 scores displayed strong temporal correlations. We found five patterns in the PHQ-8 and the Item 9 trajectories. We also found 8% - 13% of the patients have experienced an increase in suicidal ideation during the improvement of their PHQ-8. Using a trajectory-based method for subtype pattern detection in depression progression, we provided a better understanding of temporal correlations between depression symptoms over time. [ABSTRACT FROM AUTHOR]

High-performance optoelectronic devices, such as solar cells and light-emitting diodes, have been fabricated with lead halide perovskites owing to their superior carrier properties. However, charge transport in such optoelectronics is intrinsically directional due to the existence of p–n junctions, which thus lacks the potential to elucidate any perturbations in light or electricity during energy conversion. Here, with the presence of a LiCl additive in a formamidinium chloride (FACl) solution, the as-grown LiCl:FAPbCl3 nanorods demonstrate greatly enhanced crystallinity and UV photoresponse as compared to pristine FAPbCl3 nanostructures without the LiCl additive. Most importantly, the LiCl:FAPbCl3 nanorod film exhibits unprecedented distinguishability to UV photons with different energies and oscillating intensities, in the form of bipolar and periodically oscillatory photocurrents. This work could advance the fundamental understanding of photoinduced carrier processes in halide perovskites and facilitate the development of novel UV-based optical communications. [ABSTRACT FROM AUTHOR]

We report a simple technique for the realization of fiber-based Fabry-Pérot microcavities with large Q/V values as well as high cavity-to-fiber coupling efficiencies. The open microcavity we demonstrate consists of a flat mirror and a concave mirror on the tip of a single mode optical fiber. Combining hydrofluoric acid chemical wet etching with CO2 laser reflow, we obtain a fiber-tip atomically smooth concave surface with a diameter of 4.7 μm determined by the fiber core size. The concave surface with a spherical profile is automatically aligned with the fiber core, which enables high cavity-to-fiber power coupling efficiency (higher than 90%) with an optimal fiber-tip mirror's radius of curvature based on numerical simulation results. After distributed-Bragg-reflector coating, we have realized a wavelength-tunable open microcavity with a quality factor Q exceeding 1000 and a mode volume V of 13.6 μm3, and laser emission is demonstrated from this microcavity. [ABSTRACT FROM AUTHOR]

The effects of proton irradiation on nanostructured metal oxides have been investigated. Recent studies suggest that the presence of structural defects (e.g. vacancies and interstitials) in metal oxides may enhance the material's electrochemical charge storage capacity. A new approach to introduce defects in electrode materials is to use ion irradiation as it can produce a supersaturation of point defects in the target material. In this work we report the effect of low-energy proton irradiation on amorphous TiO2 nanotube electrodes at both room temperature and high temperature (250 °C). Upon room temperature irradiation the nanotubes demonstrate an irradiation-induced phase transformation to a mixture of amorphous, anatase, and rutile domains while showing a 35% reduction in capacity compared to anatase TiO2. On the other hand, the high temperature proton irradiation induced a disordered rutile phase within the nanotubes as characterized by Raman spectroscopy and transmission electron microscopy, which displays an improved capacity by 20% at ∼240 mA h g−1 as well as improved rate capability compared to an unirradiated anatase sample. Voltammetric sweep data were used to determine the contributions from diffusion-limited intercalation and capacitive processes and it was found that the electrodes after irradiation had more contributions from diffusion in lithium charge storage. Our work suggests that tailoring the defect generation through ion irradiation within metal oxide electrodes could present a new avenue for designing advanced electrode materials. [ABSTRACT FROM AUTHOR]

Bond length and bond angle exhibited by valence electrons is essential to the core of chemistry. Using lead-based organic-inorganic perovskite compounds as an exploratory platform, it is demonstrated that the modulation of valence electrons by compression can lead to discovery of new properties of known compounds. Yet, despite its unprecedented progress, further efficiency boost of lead-based organic-inorganic perovskite solar cells is hampered by their wider bandgap than the optimum value according to the Shockley-Queisser limit. By modulating the valence electron wavefunction with modest hydraulic pressure up to 2.1 GPa, the optimized bandgap for single-junction solar cells in lead-based perovskites, for the first time, is achieved by narrowing the bandgap of formamidinium lead triiodide (HC(NH2)2PbI3) from 1.489 to 1.337 eV. Strikingly, such bandgap narrowing is partially retained after the release of pressure to ambient, and the bandgap narrowing is also accompanied with double-prolonged carrier lifetime. With First-principles simulation, this work opens a new dimension in basic chemical understanding of structural photonics and electronics and paves an alternative pathway toward better photovoltaic materials-by-design. [ABSTRACT FROM AUTHOR]

Two pseudohalide thiocyanate ions (SCN−) have been used to replace two iodides in CH3NH3PbI3, and the resulting perovskite material was used as the active material in solar cells. In accelerated stability tests, the CH3NH3Pb(SCN)2I perovskite films were shown to be superior to the conventional CH3NH3PbI3 films as no significant degradation was observed after the film had been exposed to air with a relative humidity of 95 % for over four hours, whereas CH3NH3PbI3 films degraded in less than 1.5 hours. Solar cells based on CH3NH3Pb(SCN)2I thin films exhibited an efficiency of 8.3 %, which is comparable to that of CH3NH3PbI3 based cells fabricated in the same way. [ABSTRACT FROM AUTHOR]

Two pseudohalide thiocyanate ions (SCN−) have been used to replace two iodides in CH3NH3PbI3, and the resulting perovskite material was used as the active material in solar cells. In accelerated stability tests, the CH3NH3Pb(SCN)2I perovskite films were shown to be superior to the conventional CH3NH3PbI3 films as no significant degradation was observed after the film had been exposed to air with a relative humidity of 95 % for over four hours, whereas CH3NH3PbI3 films degraded in less than 1.5 hours. Solar cells based on CH3NH3Pb(SCN)2I thin films exhibited an efficiency of 8.3 %, which is comparable to that of CH3NH3PbI3 based cells fabricated in the same way. [ABSTRACT FROM AUTHOR]

Halide Perovskites: Suppressed Lattice Disorder for Large Emission Enhancement and Structural Robustness in Hybrid Lead Iodide Perovskite Discovered by High-Pressure Isotope Effect (Adv. Funct. Perovskite, high-pressure, bandgap, mechanical and optical properties, stability Keywords: perovskite; high-pressure; bandgap; mechanical and optical properties; stability EN perovskite high-pressure bandgap mechanical and optical properties stability 1 1 1 02/26/21 20210224 NES 210224 In article number 2009131, Gang Liu and co-workers conduct high-pressure isotope research to discover a significantly suppressed lattice disorder realized by H/D substitution in hybrid halide perovskites, which reveals large emission enhancement and strong structural robustness in isotope-functionalized perovskite materials. [Extracted from the article]

Nanowire lasers hold great potential as nanoscale coherent light sources. The rapid wavelength tuning of such light sources is one of the most important parameters for practical applications. Although significant efforts have been made in the past decades, the fast and reversible lasing wavelength tuning in nanowires or structures alike remains a challenge. Here, by incorporating temperature‐dependent Varshni shift of the bandgap with ultralow thermal inertia of a free‐standing cadmium sulfide (CdS) nanowire, a fast lasing wavelength tuning in single nanowires with excellent reversibility is demonstrated. Above room temperature, a Varshni shift rate (≈0.16 nm K−1) twice larger than that at low temperature (≈ 0.085 nm K−1) is observed, and the nanowire lasing peak is tuned from 514 to 549 nm with step down to 0.075 nm K−1. Using a beam of CO2 laser pulses to instantaneously modulate the temperature of a free‐standing lasing nanowire, a reversible wavelength tuning at a rate of ≈48 000 nm s−1, which is about three orders of magnitude faster than that reported previously is achieved. The results herein suggest a very promising route to fast wavelength tuning in lasing nanowires or other nanostructures, which may lead to fast tunable nanolasers for a variety of nanophotonic applications. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid perovskites such as methylammonium lead iodide (CH3NH3PbI3) are game-changing semiconductors for solar cells and light-emitting devices owing to their defect tolerance and exceptionally long carrier lifetimes and diffusion lengths. Determining whether the dynamically disordered organic cations with large dipole moment benefit the optoelectronic properties of CH3NH3PbI3 has been an outstanding challenge. Herein, via transient absorption measurements employing an infrared pump pulse tuned to a methylammonium vibration, we observe slow, nanosecond-long thermal dissipation from the selectively excited organic mode to the inorganic sublattice. The resulting transient electronic signatures, during the period of thermal-nonequilibrium when the induced thermal motions are mostly concentrated on the organic sublattice, reveal that the induced atomic motions of the organic cations do not alter the absorption or the photoluminescence response of CH3NH3PbI3, beyond thermal effects. Our results suggest that the attractive optoelectronic properties of CH3NH3PbI3 mainly derive from the inorganic lead-halide framework. It has been challenging to probe whether dynamically disordered organic cations affect optical properties of CH3NH3PbI3. Here, Guo et al. employ infrared-pump electronic-probe spectroscopy and show that pump-induced atomic motions of the organic cations do not substantially alter optoelectronic properties. [ABSTRACT FROM AUTHOR]

A correction to the article "Pseudohalide-Induced Moisture-Tolerance in Perovskite CH3NH3Pb(SCN)2I Thin Films" that was published in the 2015 issue is presented.