Explore the vast range of titles available.

Quantum dot (QD) solids are an emerging platform for developing a range of optoelectronic devices. Thus, understanding exciton dynamics is essential towards developing and optimizing QD devices. Here, using transient absorption microscopy, we reveal the initial exciton dynamics in QDs with femtosecond timescales. We observe high exciton diffusivity (~10 2  cm 2  s –1 ) in lead chalcogenide QDs within the first few hundred femtoseconds after photoexcitation followed by a transition to a slower regime (~10 –1 –1 cm 2  s –1 ). QD solids with larger interdot distances exhibit higher initial diffusivity and a delayed transition to the slower regime, while higher QD packing density and heterogeneity accelerate this transition. The fast transport regime occurs only in materials with exciton Bohr radii much larger than the QD sizes, suggesting the transport of delocalized excitons in this regime and a transition to slower transport governed by exciton localization. These findings suggest routes to control the optoelectronic properties of QD solids. Understanding exciton dynamics in quantum dots is important for realizing their potential in optoelectronics. Here, the authors use femtosecond transient absorption microscopy to reveal ultrafast exciton transport, enhanced at larger interdot distance and taking place within hundreds of femtoseconds after generation.

Reduced-dimensional perovskites are attractive light-emitting materials due to their efficient luminescence, color purity, tunable bandgap, and structural diversity. A major limitation in perovskite light-emitting diodes is their limited operational stability. Here we demonstrate that rapid photodegradation arises from edge-initiated photooxidation, wherein oxidative attack is powered by photogenerated and electrically-injected carriers that diffuse to the nanoplatelet edges and produce superoxide. We report an edge-stabilization strategy wherein phosphine oxides passivate unsaturated lead sites during perovskite crystallization. With this approach, we synthesize reduced-dimensional perovskites that exhibit 97 ± 3% photoluminescence quantum yields and stabilities that exceed 300 h upon continuous illumination in an air ambient. We achieve green-emitting devices with a peak external quantum efficiency (EQE) of 14% at 1000 cd m −2 ; their maximum luminance is 4.5 × 10 4  cd m −2 (corresponding to an EQE of 5%); and, at 4000 cd m −2 , they achieve an operational half-lifetime of 3.5 h. Reduced-dimensional halide perovskites are promising for light-emitting diodes but suffer from photo-degradation. Here Quan et al. identify the edge of the perovskite nanoplatelets as the degradation channels and use phosphine oxides to passivate the edges and boost device performance and lifetime.

Background Rheumatoid arthritis (RA) is characterized by persistent synovial inflammation, yet the molecular mechanisms distinguishing early from late-stage disease remain incompletely elucidated. Identifying stage-specific biomarkers and pathogenic cellular interactions is crucial for precision medicine. Objective To comprehensively characterize the transcriptomic landscape and cellular composition of early versus late RA synovium, identify diagnostic biomarkers, and elucidate key pathogenic cell–cell interactions driving disease chronicity. Methods Synovial tissues from 51 RA patients (13 early, 38 late-stage) were analyzed using histopathology, immunohistochemistry, bulk RNA sequencing ( n  = 19),and single-cell RNA sequencing (scRNA-seq, n  = 6; 3 Early RA vs. 3 Late-stage RA).Machine learning algorithms (LASSO, SVM-RFE, random forest) were employed to identify diagnostic biomarkers. An artificial neural network (ANN) model was constructed and validated. Cell–cell communication analysis was performed using CellChat. Results Histopathological analysis revealed significantly increased infiltration of macrophages (CD68 +) and plasma cells (CD138 +) in late-stage RA ( P  < 0.05). RNA sequencing identified 87 differentially expressed genes, with interferon-stimulated genes significantly upregulated. Integrated machine learning identified a minimal three-gene signature (CXCL10, ISG15, IFIH1) as a promising candidate model for RA staging. The three-gene ANN model showed excellent diagnostic performance (AUC = 0.922). Notably, CXCL10 emerged as the most critical component, demonstrating potentially high classification accuracy in this cohort (AUC = 0.767) and standing as the sole independent predictor in multivariable analysis (OR = 7.271, P  = 0.022). CXCL10 high expression was strongly associated with M1 macrophage infiltration ( r  = 0.446, P  = 0.005) and enriched in chemokine and JAK-STAT pathways. scRNA-seq revealed macrophages as the primary source of CXCL10, with upstream stimulation from CD8 + T cells via the IFN-γ-CXCL10-CXCR3 axis. Critically, we identified an expanded TREM2 + macrophage subset in late RA, which highly expressed APRIL (TNFSF13) and expanded in parallel with plasma cells expressing APRIL receptors (BCMA + /TACI +). This TREM2 + macrophage-plasma cell niche may represent a potential pathogenic circuit that could contribute to autoimmune chronicity. Conclusions Late-stage RA appears to be characterized by a CXCL10-driven inflammatory signature and an expanded TREM2 + macrophage-plasma cell survival niche. CXCL10 represents a promising candidate biomarker for disease staging that may have mechanistic links to pathogenesis. The IFN-γ-CXCL10-CXCR3 axis and the APRIL-BCMA/TACI pathway may constitute potential therapeutic targets for refractory RA.

While total internal reflection (TIR) lays the foundation for many important applications, foremost fibre optics that revolutionised information technologies, it is undesirable in some other applications such as light-emitting diodes (LEDs), which are a backbone for energy-efficient light sources. In the case of LEDs, TIR prevents photons from escaping the constituent high-index materials. Advances in material science have led to good efficiencies in generating photons from electron–hole pairs, making light extraction the bottleneck of the overall efficiency of LEDs. In recent years, the extraction efficiency has been improved, using nanostructures at the semiconductor/air interface that outcouple trapped photons to the outside continuum. However, the design of geometrical features for light extraction with sizes comparable to or smaller than the optical wavelength always requires sophisticated and time-consuming fabrication, which causes a gap between lab demonstration and industrial-level applications. Inspired by lightning bugs, we propose and realise a disordered metasurface for light extraction throughout the visible spectrum, achieved with single-step fabrication. By applying such a cost-effective light extraction layer, we improve the external quantum efficiency by a factor of 1.65 for commercialised GaN LEDs, demonstrating a substantial potential for global energy-saving and sustainability.

Bandtail states in disordered semiconductor materials result in losses in open-circuit voltage ( V oc ) and inhibit carrier transport in photovoltaics. For colloidal quantum dot (CQD) films that promise low-cost, large-area, air-stable photovoltaics, bandtails are determined by CQD synthetic polydispersity and inhomogeneous aggregation during the ligand-exchange process. Here we introduce a new method for the synthesis of solution-phase ligand-exchanged CQD inks that enable a flat energy landscape and an advantageously high packing density. In the solid state, these materials exhibit a sharper bandtail and reduced energy funnelling compared with the previous best CQD thin films for photovoltaics. Consequently, we demonstrate solar cells with higher V oc and more efficient charge injection into the electron acceptor, allowing the use of a closer-to-optimum bandgap to absorb more light. These enable the fabrication of CQD solar cells made via a solution-phase ligand exchange, with a certified power conversion efficiency of 11.28%. The devices are stable when stored in air, unencapsulated, for over 1,000 h. An improved ligand-exchange process allows the realization of solution-deposited films of quantum dots with reduced energetic disorder and, as a result, solar cells with improved open-circuit voltage, charge-carrier transport and stability.

Control over carrier type and doping levels in semiconductor materials is key for optoelectronic applications. In colloidal quantum dots (CQDs), these properties can be tuned by surface chemistry modification, but this has so far been accomplished at the expense of reduced surface passivation and compromised colloidal solubility; this has precluded the realization of advanced architectures such as CQD bulk homojunction solids. Here we introduce a cascade surface modification scheme that overcomes these limitations. This strategy provides control over doping and solubility and enables n -type and p -type CQD inks that are fully miscible in the same solvent with complete surface passivation. This enables the realization of homogeneous CQD bulk homojunction films that exhibit a 1.5 times increase in carrier diffusion length compared with the previous best CQD films. As a result, we demonstrate the highest power conversion efficiency (13.3%) reported among CQD solar cells. It is challenging to realize doping and surface passivation simultaneously in colloidal quantum dot inks. Here Choi et al . employ a cascade surface modification approach to solve the problem and obtain record high efficiency of 13.3% for bulk homojunction solar cells based on these inks.

Colloidal quantum dots (CQDs) are promising photovoltaic (PV) materials because of their widely tunable absorption spectrum controlled by nanocrystal size1,2. Their bandgap tunability allows not only the optimization of single-junction cells, but also the fabrication of multijunction cells that complement perovskites and silicon3. Advances in surface passivation2,4–7, combined with advances in device structures8, have contributed to certified power conversion efficiencies (PCEs) that rose to 11% in 20169. Further gains in performance are available if the thickness of the devices can be increased to maximize the light harvesting at a high fill factor (FF). However, at present the active layer thickness is limited to ~300 nm by the concomitant photocarrier diffusion length. To date, CQD devices thicker than this typically exhibit decreases in short-circuit current (JSC) and open-circuit voltage (VOC), as seen in previous reports3,9–11. Here, we report a matrix engineering strategy for CQD solids that significantly enhances the photocarrier diffusion length. We find that a hybrid inorganic–amine coordinating complex enables us to generate a high-quality two-dimensionally (2D) confined inorganic matrix that programmes internanoparticle spacing at the atomic scale. This strategy enables the reduction of structural and energetic disorder in the solid and concurrent improvements in the CQD packing density and uniformity. Consequently, planar devices with a nearly doubled active layer thicknesses (~600 nm) and record values of JSC (32 mA cm−2) are fabricated. The VOC improved as the current was increased. We demonstrate CQD solar cells with a certified record efficiency of 12%.

Decoding arbitrary polarization information in a cost-effective way is a key target for next-generation optical sensing. However, the design of full-Stokes detectors capable of resolving polarization states in a single shot remains challenging. Here we introduce GOStokes, an approach that leverages heterogeneous grain orientation in solution-processed metal halide semiconductors to extract Stokes parameters in a single measurement. By developing polycrystalline films exhibiting strong inherent circular and linear dichroism, we harness randomly oriented grains to produce varied polarization selectivity across the spatial domain. Integrating these films as multi-channel optical filters with commercial cameras enables real-time polarimetric detection and imaging, each generating a transmission map from a single exposure. Using deep learning, GOStokes precisely determines arbitrary polarization states with an averaged mean absolute error below 1%. Our demonstration underscores the potential of combining low-cost, scalable, polycrystalline films with reconstruction algorithms for advanced polarimetric applications. Traditional polarization detection has relied on bulky optics and is inherently slow. Here, the authors present GOStokes, a single-shot method enabled by heterogeneous grain orientation in chiral, polycrystalline thin films.

The stability of solution-processed semiconductors remains an important area for improvement on their path to wider deployment. Inorganic caesium lead halide perovskites have a bandgap well suited to tandem solar cells 1 but suffer from an undesired phase transition near room temperature 2 . Colloidal quantum dots (CQDs) are structurally robust materials prized for their size-tunable bandgap 3 ; however, they also require further advances in stability because they are prone to aggregation and surface oxidization at high temperatures as a consequence of incomplete surface passivation 4 , 5 . Here we report ‘lattice-anchored’ hybrid materials that combine caesium lead halide perovskites with lead chalcogenide CQDs, in which lattice matching between the two materials contributes to a stability exceeding that of the constituents. We find that CQDs keep the perovskite in its desired cubic phase, suppressing the transition to the undesired lattice-mismatched phases. The stability of the CQD-anchored perovskite in air is enhanced by an order of magnitude compared with pristine perovskite, and the material remains stable for more than six months at ambient conditions (25 degrees Celsius and about 30 per cent humidity) and more than five hours at 200 degrees Celsius. The perovskite prevents oxidation of the CQD surfaces and reduces the agglomeration of the nanoparticles at 100 degrees Celsius by a factor of five compared with CQD controls. The matrix-protected CQDs show a photoluminescence quantum efficiency of 30 per cent for a CQD solid emitting at infrared wavelengths. The lattice-anchored CQD:perovskite solid exhibits a doubling in charge carrier mobility as a result of a reduced energy barrier for carrier hopping compared with the pure CQD solid. These benefits have potential uses in solution-processed optoelectronic devices. The stability of both colloidal quantum dots and perovskites can be improved by combining them into a hybrid material in which matched lattice parameters suppress the formation of undesired phases.

Lactate has been traditionally regarded as a mere byproduct of glycolysis or metabolic waste. However, an increasing body of literature suggests its critical role in regulating various physiological and pathological processes. Lactate is generally associated with hypoxia, inflammation, viral infections, and tumors. It performs complex physiological roles by activating monocarboxylate transporter (MCT) or the G protein-coupled receptor GPR81 across the cell membrane. Lactate exerts immunosuppressive effects by regulating the functions of various immune cells (such as natural killer cells, T cells, dendritic cells, and monocytes) and its role in macrophage polarization and myeloid-derived suppressor cell (MDSC) differentiation in the tumor microenvironment. Lactic acid has also recently been found to increase the density of CD8 + T cells, thereby enhancing the antitumor immune response. Acute or chronic inflammatory diseases have opposite immune states in the inflammatory disease microenvironment. Factors such as cell types, transcriptional regulators, ionic mediators, and the microenvironment all contribute to the diverse functions lactate exhibits. Herein, we reviewed the pleiotropic effects of lactate on the regulation of various functions of immune cells in the tumor microenvironment and under inflammatory conditions, which may help to provide new insights and potential targets for the diagnosis and treatment of inflammatory diseases and malignancies.