Michael Saliba, Taisuke Matsui, Konrad Domanski
et al.
Improving the stability of perovskite solar cells Inorganic-organic perovskite solar cells have poor long-term stability because ultraviolet light and humidity degrade these materials. Bella et al. show that coating the cells with a water-proof fluorinated polymer that contains pigments to absorb ultraviolet light and re-emit it in the visible range can boost cell efficiency and limit photodegradation. The performance and stability of inorganic-organic perovskite solar cells are also limited by the size of the cations required for forming a correct lattice. Saliba et al. show that the rubidium cation, which is too small to form a perovskite by itself, can form a lattice with cesium and organic cations. Solar cells based on these materials have efficiencies exceeding 20% for over 500 hours if given environmental protection by a polymer coating. Science, this issue pp. 203 and 206 The seemingly too small rubidium cation was successfully integrated into perovskite solar cells. All of the cations currently used in perovskite solar cells abide by the tolerance factor for incorporation into the lattice. We show that the small and oxidation-stable rubidium cation (Rb+) can be embedded into a “cation cascade” to create perovskite materials with excellent material properties. We achieved stabilized efficiencies of up to 21.6% (average value, 20.2%) on small areas (and a stabilized 19.0% on a cell 0.5 square centimeters in area) as well as an electroluminescence of 3.8%. The open-circuit voltage of 1.24 volts at a band gap of 1.63 electron volts leads to a loss in potential of 0.39 volts, versus 0.4 volts for commercial silicon cells. Polymer-coated cells maintained 95% of their initial performance at 85°C for 500 hours under full illumination and maximum power point tracking.
Weyl physics emerges in the laboratory Weyl fermions—massless particles with half-integer spin—were once mistakenly thought to describe neutrinos. Although not yet observed among elementary particles, Weyl fermions may exist as collective excitations in so-called Weyl semimetals. These materials have an unusual band structure in which the linearly dispersing valence and conduction bands meet at discrete “Weyl points.” Xu et al. used photoemission spectroscopy to identify TaAs as a Weyl semimetal capable of hosting Weyl fermions. In a complementary study, Lu et al. detected the characteristic Weyl points in a photonic crystal. The observation of Weyl physics may enable the discovery of exotic fundamental phenomena. Science, this issue p. 613 and 622 Angle-resolved photoemission is used to detect the topological surface states and bulk dispersion of the compound tantalum arsenide. [Also see Report by Lu et al.] A Weyl semimetal is a new state of matter that hosts Weyl fermions as emergent quasiparticles and admits a topological classification that protects Fermi arc surface states on the boundary of a bulk sample. This unusual electronic structure has deep analogies with particle physics and leads to unique topological properties. We report the experimental discovery of a Weyl semimetal, tantalum arsenide (TaAs). Using photoemission spectroscopy, we directly observe Fermi arcs on the surface, as well as the Weyl fermion cones and Weyl nodes in the bulk of TaAs single crystals. We find that Fermi arcs terminate on the Weyl fermion nodes, consistent with their topological character. Our work opens the field for the experimental study of Weyl fermions in physics and materials science.
Quantum spin Hall (QSH) effect materials feature edge states that are topologically protected from backscattering. However, the small band gap in materials that have been identified as QSH insulators limits applications. We use first-principles calculations to predict a class of large-gap QSH insulators in two-dimensional transition metal dichalcogenides with 1T′ structure, namely, 1T′-MX2 with M = (tungsten or molybdenum) and X = (tellurium, selenium, or sulfur). A structural distortion causes an intrinsic band inversion between chalcogenide-p and metal-d bands. Additionally, spin-orbit coupling opens a gap that is tunable by vertical electric field and strain. We propose a topological field effect transistor made of van der Waals heterostructures of 1T′-MX2 and two-dimensional dielectric layers that can be rapidly switched off by electric field through a topological phase transition instead of carrier depletion. First-principles calculations are used to predict an exotic effect in a particular structure of WTe2 and related materials. Predicting an exotic state of matter Much like graphene, twodimensional flakes of transition metal dichalcogenides have appealing electronic properties. Qian et al. now find that certain structures of these materials may also exhibit the so-called spin Hall effect. The spin Hall effect represents an exotic state of matter in which a 2D material conducts electricity along its edge in a way that drastically reduces dissipation. To show this, the researchers used first-principle calculations and found that the materials also feature a large band gap, which reduces undesirable conduction through the bulk. Their proposed device could be switched on and off quickly using an electric field. Science, this issue p. 1344
Abstract Development of polymer-based smart materials, which can autonomously alter their physical and/or chemical properties when exposed to external stimuli, is a thriving research frontier in contemporary advanced functional materials science. Poly(N-isopropylacrylamide) (PNIPAM)-based smart hydrogels are known to exhibit distinct thermo-responsive properties near a lower critical solution temperature (LCST), which have found diverse promising applications such as smart coating, drug delivery, tissue regeneration, and artificial muscles. In this review, we provide an up-to-date account on the recent developments in advanced functional PNIPAM-based smart hydrogels and their emerging technological applications in the fields of smart actuators, photonic crystals, smart windows and novel biomedical applications. The fundamental design and synthetic strategies of PNIPAM-based smart hydrogels are discussed. Their unique properties, underlying mechanisms and potential applications in different fields are highlighted. Finally, this review provides a brief conclusion and enumerates the challenges and opportunities in this rising area of research and development involving these intriguing polymer-based advanced smart systems rooted in chemistry and materials science. It is expected that this review would provide significant insights for the development of reconfigurable and programmable advanced smart materials with numerous possibilities, prompting the rapid advancement of this highly interdisciplinary area, which encompasses materials science, polymer science, synthetic chemistry, device engineering, physics, biology, nanoscience and nanotechnology.
Blue photoluminescence from chemically derived graphene oxide Goki Eda, Yun-Yue Lin, Cecilia Mattevi, Hisato Yamaguchi, Hsin-An Chen, I-Sheng Chen, Chun-Wei Chen, and Manish Chhowalla 1 Department of Materials, Imperial College, Exhibition Road, London SW7 2AZ, UK. 2 Department of Materials Science and Engineering, Rutgers University 607 Taylor Road, Piscataway, NJ 08854, USA. 3 Department of Materials Science and Engineering, National Taiwan University No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan.
Collective electronic excitations at metal surfaces are well known to play a key role in a wide spectrum of science, ranging from physics and materials science to biology. Here we focus on a theoretical description of the many-body dynamical electronic response of solids, which underlines the existence of various collective electronic excitations at metal surfaces, such as the conventional surface plasmon, multipole plasmons and the recently predicted acoustic surface plasmon. We also review existing calculations, experimental measurements and applications.
A multi-reference source spanning the whole composites science field, this text covers such topics as: fibre reinforcements and general theory of composites; polymer matrix composites; metal matrix composites; test methods, nondestructive evaluation and smart composites; and design and application.
IntroductionThis meta-analysis aimed to evaluate the safety and efficacy of anti-IL-5 monoclonal antibody (anti-IL-5 mAb) as a second-line therapy for chronic rhinosinusitis with nasal polyps (CRSwNP).Materials and methodsFour databases (PubMed, Web of Science, Embase and Cochrane Library) were searched from the establishment of the databases to September 15, 2025, for randomized controlled trials (RCTs) comparing anti-IL-5 mAb versus placebo in the treatment of CRSwNP. The primary outcome measure of this meta-analysis were nasal polyp score (NPS) and Sino-Nasal Outcome Test-22 (SNOT-22) score. Secondary outcome measures included nasal blockage score (NBS), loss of smell score (LSS), Lund-Mackay score (LMS), University of Pennsylvania Smell Identification Test (UPSIT) score, nasal overall visual analog scale(VAS) score, nasal composite visual analog scale(VAS) score, number of first-time NP surgery patients and number of systemic corticosteroids (≥1 course) patients.ResultsTotally 10 RCTs were included for meta-analysis. Compared with placebo, anti-IL-5 mAb provided a significantly lower NPS (WMD = -0.58, 95%CI: -0.70 ~ -0.46, P < 0.00001, I2 = 83%), SNOT-22 score (WMD: -9.57, 95% CI: -11.03 ~ -8.11, P < 0.00001, I2 = 80%), NBS (SMD: -1.75; 95% CI: -3.13 ~ -0.36, P = 0.01, I2 = 99%), LSS (SMD: -1.68; 95% CI: -3.13 ~ -0.24, P = 0.02, I2 = 99%), LMS (WMD: -2.00; 95% CI: -2.65 ~ -1.34, P < 0.00001, I2 = 97%), nasal overall VAS score (WMD: -1.54, 95% CI: -1.64 ~ -1.43, P < 0.00001, I2 = 0%), nasal composite VAS score (WMD: -1.28, 95% CI: -1.66 ~ -0.19, P < 0.00001, I2 = 0%), number of first-time NP surgery patients (RR: 0.64, 95% CI: 0.41 ~ 1.00, P = 0.05, I2 = 69%) and number of systemic corticosteroids (≥1 course) patients (RR: 0.73, 95% CI: 0.62 ~ 0.86, P = 0.0002, I2 = 0%), while significantly improved UPSIT (WMD: 2.09, 95% CI: 0.42 ~ 3.77, P = 0.01, I2 = 0%).ConclusionsThis results confirmed that anti-IL-5 mAb therapy was safe and effective for CRSwNP and can serve as a second-line therapy.Systematic review registrationhttps://www.crd.york.ac.uk/prospero/, identifier CRD420251170717.
The process conditions, content of ingredients and in vitro antioxidant activity of Piper nigrum L. polysaccharides (PNP) by ultrasound-assisted extraction (UAE) and PNP by hot water extraction (HWE) were compared. The findings demonstrated that the UAE produced greater polysaccharides content (74.41 %) with the yield of PNP (2.9 %) than HWE. The ideal conditions were 324 W of ultrasonic power, 36 mL/g of liquid to material ratio, 70 min of ultrasonic time, and 78 °C of temperature. Structural analysis showed UAE-PNP was the α-type polysaccharides with a pyran ring structure, which were mainly neutral polysaccharides. In addition, UAE-PNP had great antioxidant activity, especially in its ability to scavenge ABTS free radicals. According to the experimental results, the UAE method was an efficient way to extract PNP. This experiment showed for the first time the structure and antioxidant activity of HWE-PNP and UAE-PNP, which provided some theoretical proof for the application of PNP in food additives and biopharmaceuticals.