Kim and co-workers report systematical studies with methylammonium chloride (MACl) in formamidinium lead iodide (FAPbI 3 )-based perovskite thin films. The MACl addition could induce the intermediate phase with pure a-phase without annealing, effectively stabilizing the structure, only through cationic site substitution. The film quality can be significantly improved, exhibiting a 63 increase in grain size, a 33 increase in phase crystallinity, and a 4.33 increase in photoluminescence lifetime. The resulting optimized solar cells achieved a peakscan efficiency of above 24%.

The rapid detection of biological and chemical substances in real time is particularly important for public health and environmental monitoring and in the military sector. If the process of substance detection to visual reporting can be implemented into a single miniaturized sensor, there could be a profound impact on practical applications. Here, we propose a compact sensor platform that integrates liquid crystals (LCs) and holographic metasurfaces to autonomously sense the existence of a volatile gas and provide an immediate visual holographic alarm. By combining the advantage of the rapid responses to gases realized by LCs with the compactness of holographic metasurfaces, we develop ultracompact gas sensors without additional complex instruments or machinery to report the visual information of gas detection. To prove the applicability of the compact sensors, we demonstrate a metasurface-integrated gas sensor on safety goggles via a one-step nanocasting process that is attachable to flat, curved, and flexible surfaces.

Metalenses have shown a number of promising functionalities that are comparable with conventional refractive lenses. However, current metalenses are still far from commercialization due to the formidable fabrication costs. Here, we demonstrate a low-cost dielectric metalens that works in the visible spectrum. The material of the metalens consists of a matrix-inclusion composite in which a hierarchy satisfies two requirements for the single-step fabrication; a high refractive index and a pattern-transfer capability. We use a UV-curable resin as a matrix to enable direct pattern replication by the composite, and titanium dioxide nanoparticles as inclusions to increase the refractive index of the composite. Therefore, such a dielectric metalens can be fabricated with a single step of UV nanoimprint lithography. An experimental demonstration of the nanoparticle composite-based metalens validates the feasibility of our approach and capability for future applications. Our method allows rapid replication of metalenses repeatedly and thereby provides an advance toward the use of metalenses on a commercial scale.

Daytime radiative coolers are used to pump excess heat from a target object into a cold exterior space without energy consumption. Radiative coolers have become attractive cooling options. In this study, a daytime radiative cooler was designed to have a selective emissive property of electromagnetic waves in the atmospheric transparency window of 8–13 μm and preserve low solar absorption for enhancing radiative cooling performance. The proposed daytime radiative cooler has a simple multilayer structure of inorganic materials, namely, Al2O3, Si3N4, and SiO2, and exhibits high emission in the 8–13 μm region. Through a particle swarm optimization method, which is based on an evolutionary algorithm, the stacking sequence and thickness of each layer were optimized to maximize emissions in the 8–13 μm region and minimize the cooling temperature. The average value of emissivity of the fabricated inorganic radiative cooler in the 8–13 μm range was 87%, and its average absorptivity in the solar spectral region (0.3–2.5 μm) was 5.2%. The fabricated inorganic radiative cooler was experimentally applied for daytime radiative cooling. The inorganic radiative cooler can reduce the temperature by up to 8.2 °C compared to the inner ambient temperature during the daytime under direct sunlight.

intermediate phase is another very effective way to transfer a uniform and high-quality perovskite fi lm because the intermediate phase can slow down the reaction between PbI 2 and FAI in solution. [ 27 ] Recently, intramolecular exchange has been shown to dramatically improve the power conversion effi ciency of perovskite solar cells (PSCs), and such exchange of DMSO intercalated in PbI 2 (PbI 2 (DMSO) complex) with FAI leads to crystallization of FAPbI 3 because FAI has a higher affi nity for PbI 2 than does DMSO. [ 9 ] This exchange neither increased the volume nor changed the thickness of the as-coated PbI 2 (DMSO) fi lm because the molecular sizes of FAI and DMSO are similar, and hence a stable, dense, and uniform perovskite fi lm was fabricated.The intercalation of layered PbI 2 with different organic molecules has been studied a useful method to fabricate inorganic-organic compounds with novel properties. [ 28 ] The structure of PbI 2 consists in sandwich-type layers, which contains a plane of Pb ions sandwich-type between two planes of hexagonally arranged I ions. The ionic bonds within I-Pb-I layers are strong while those between adjacent sandwiched layers are weak. [ 29 ] Therefore, the van der Waals interactions between interlayer bonding allows a successfully insertion of different guest molecules. [ 30,31 ] As mentioned above, the PbI 2 (DMSO) complex (DMSO intercalated in layered PbI 2 ) can be successfully converted into perovskite with intramolecular exchange. In this paper, we report that the N -Methyl-2 -pyrrolidone (NMP) molecule also can be intercalated into layered PbI 2 and the PbI 2 (NMP) complex successfully converted into high-quality perovskite with intramolecular exchange. Compared to perovskite fi lms derived from the PbI 2 (DMSO) complex, those derived from the PbI 2 (NMP) complex were found to display a higherquality perovskite layer morphology and higher power conversion effi ciency. While planar perovskite solar cells derived from PbI 2 (DMSO) complex achieved a 15.8% average and 17.1% maximum power conversion effi ciency, those derived from the PbI 2 (NMP) complex achieved a 17.6% average and 19.5% maximum power conversion effi ciency.A previous study has shown that the PbI 2 (DMSO) fi lm has typically been obtained in various steps: [ 9 ] fi rst by synthesizing the PbI 2 (DMSO) 2 complex from a mixture of PbI 2 and DMSO and adding a nonpolar solvent such as toluene; then producing PbI 2 (DMSO) complex from the PbI 2 (DMSO) 2 complex by applying a vacuum oven treatment for 24 h; and fi nally dissolving PbI 2 (DMSO) complexes in DMF and spin-coating this solution on the substrate. Interestingly, we found that the PbI 2 (DMSO) or PbI 2 (NMP) fi lms could be deposited using Of the many materials and manufacturing techniques aimed at fabricating highly effi cient and low-cost photovoltaic cells, hybrid organic-inorganic solar cells that utilize perovskitebased materials as the light-harvesting component have been of great interest as an exciting alternative to third-generation photovo...

We aimed to evaluate the feasibility of diagnosing coronary stenosis and myocardial ischemia with a single dual-energy CT (DECT) acquisition. Thirty-five patients underwent contrast-enhanced, ECG-gated DECT of the heart while independently operating the two tubes of a dual-source CT system at high- and low-energy X-ray spectra. From the same raw data, coronary CTA (cCTA) studies were reconstructed for stenosis detection, and the myocardial blood-pool was analyzed by determining the tissue iodine content. Two independent observers analyzed all studies for stenosis and myocardial blood-pool deficits. Results were correlated with SPECT, coronary catheterization and cCTA on a segmental basis. cCTA had 98% sensitivity, 88% specificity and 92% accuracy for detection of >50% stenosis. DECT detected myocardial ischemia with 84% sensitivity, 94% specificity and 92% accuracy. Our initial experience may warrant further exploration of DECT as a possibly feasible single imaging investigation for the comprehensive diagnosis of coronary stenosis and myocardial ischemia.

Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm active area and 18% over a 1 cm active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

Advances in Large Language Models (LLMs) have inspired a surge of research exploring their expansion into the visual domain. While recent models exhibit promise in generating abstract captions for images and conducting natural conversations, their performance on textrich images leaves room for improvement. In this paper, we propose the Contrastive Reading Model (Cream), a novel neural architecture designed to enhance the language-image understanding capability of LLMs by capturing intricate details typically overlooked by existing methods. Cream integrates vision and auxiliary encoders, complemented by a contrastive feature alignment technique, resulting in a more effective understanding of textual information within document images. Our approach, thus, seeks to bridge the gap between vision and language understanding, paving the way for more sophisticated Document Intelligence Assistants. Rigorous evaluations across diverse tasks, such as visual question answering on document images, demonstrate the efficacy of Cream as a state-of-the-art model in the field of visual document understanding. We provide our codebase and newly-generated datasets at https://github.com/naver-ai/cream.