One of the most intensely studied scenarios of high-temperature superconductivity (HTS) postulates pairing by exchange of magnetic excitations. Indeed, such excitations have been observed up to optimal doping in the cuprates. In the heavily overdoped regime, neutron scattering measurements indicate that magnetic excitations have effectively disappeared, and this has been argued to cause the demise of HTS with overdoping. Here we use resonant inelastic X-ray scattering, which is sensitive to complementary parts of reciprocal space, to measure the evolution of the magnetic excitations in La(2-x)Sr(x)CuO4 across the entire phase diagram, from a strongly correlated insulator (x = 0) to a non-superconducting metal (x = 0.40). For x = 0, well-defined magnon excitations are observed. These magnons broaden with doping, but they persist with a similar dispersion and comparable intensity all the way to the non-superconducting, heavily overdoped metallic phase. The destruction of HTS with overdoping is therefore caused neither by the general disappearance nor by the overall softening of magnetic excitations. Other factors, such as the redistribution of spectral weight, must be considered.

Sub-second coloration of electrochromic window is realized by introducing a solid-state proton source and a tandem structure.

Low-dimensional organic−metal halides are regarded as an emerging class of X-ray scintillation materials, but most of the discovered compounds are confronted with challenges of toxicity and instability. To address these challenges, we herein report two lead-free zero-dimensional (0D) hybrid halides, (Bmpip) 2 Cu 2 Br 4 and PPh 4 CuBr 2 single crystals, grown by the low-cost solution-processing method. By single-crystal X-ray diffraction refinement, the crystal structures of (Bmpip) 2 Cu 2 Br 4 and PPh 4 CuBr 2 were determined to be orthorhombic and monoclinic crystal systems, respectively. (Bmpip) 2 Cu 2 Br 4 and PPh 4 CuBr 2 show broadband orange and yellow emissions peaking at 620 and 538 nm, respectively. Different from the emission nature of the recent reported Cu-based halide hybrids, both (Bmpip) 2 Cu 2 Br 4 and PPh 4 CuBr 2 emit from excitons bound to defects featuring spin-allowed transition, enabling them to possess fast scintillation decay time of tens of nanoseconds, respectively. In particular, the (Bmpip) 2 Cu 2 Br 4 single crystal has a high photoluminescence quantum yield of 48.2%, a high scintillation yield of 16,000 photons/MeV, and a low detection limit of 710 nGy air /s. Due to the combination of nontoxicity, long-term stability, and decent detection performance, (Bmpip) 2 Cu 2 Br 4 could be regarded as a promising X-ray scintillator.

SOX2 is a key regulator of multiple types of stem cells, especially embryonic stem cells (ESCs) and neural progenitor cells (NPCs).Understanding the mechanism underlying the function of SOX2 is of great importance for realizing the full potential of ESCs and NPCs. Here, through genome-wide comparative studies, we show that SOX2 executes its distinct functions in human ESCs (hESCs) and hESC-derived NPCs (hNPCs) through cell type-and stage-dependent transcription programs. Importantly, SOX2 suppresses non-neural lineages in hESCs and regulates neurogenesis from hNPCs by inhibiting canonical Wnt signaling. In hESCs, SOX2 achieves such inhibition by direct transcriptional regulation of important Wnt signaling modulators, WLS and SFRP2. Moreover, SOX2 ensures pluripotent epigenetic landscapes via interacting with histone variant H2A.Z and recruiting polycomb repressor complex 2 to poise developmental genes in hESCs. Together, our results advance our understanding of the mechanism by which cell type-specific transcription factors control lineage-specific gene expression programs and specify cell fate.

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In this communication, we report a new-phase 2M WSe2 with a monoclinic space group C2/m. 2M WSe2 presents a metallic behavior under ambient pressure and shows superconducting transition with a maximum Tc of 7.3 K at 10.7 GPa.

Lead halide perovskites have emerged as promising photovoltaic (PV) materials owing to their superior optoelectronic properties. However, they suffer from poor stability and potential toxicity. Here, computational screening with experimental synthesis is combined to explore stable, lead-free, and defect-tolerant PV materials. Heavy cations with lone-pair electrons and mixed anions of chalcogens and halogens as a descriptor for simultaneous realization of defect tolerance and high stability are adopted. Together with the criteria of possessing direct band gap and optimal gap value, the inorganic material database is screened and CuBiSCl 2 in the post-perovskite structure is identified with an ideal band gap of 1.37 eV. The electronic structure and defect calculations suggest its defect-tolerant characteristics. By optical absorption measurement, its band gap is confirmed to be ≈1.44 eV, with strong absorption near the band edge. The material is stable against thermal decomposition up to 300 °C and can survive from 25 days of storage at ambient conditions with 60% relative humidity. Prototype solar cells are fabricated and demonstrate an open circuit voltage of 1.09 V and a power conversion efficiency of 1.00%. With the excellent properties above, CuBiSCl 2 is proposed to be a promising candidate for PV application.

Metal halide perovskites have excited tremendous research interests due to their extraordinary photovoltaic and optoelectronic performance. Cs2SnI6 has emerged as a promising lead-free perovskite in advanced optoelectronics due to its high stability, appropriate bandgap, and high absorption coefficient. The performance of two-dimensional (2D) Cs2SnI6-based photodetectors is limited as compared to lead-based perovskites. Here, we report a simple strategy for incorporating aliovalent metal ions (nickel and zinc) for doping or passivation of perovskites to improve their performance. Aliovalent metal ions are employed to break the inherent dark transition of the 2D Cs2SnI6, greatly increasing photoluminescence by two orders of magnitude than pristine Cs2SnI6. Density function calculation reveals the n-type doping of nickel ions without introducing any deep trap states. We further demonstrate that the surface passivation of 2D Cs2SnI6 by zinc ions can greatly reduce surface trap/defect density. Aliovalent metal ion-incorporated Cs2SnI6 perovskites exhibit broadband detection, high responsivity (1.6 × 103 A W–1, for Ni-incorporated Cs2SnI6) and high detectivity (1.56 × 1013 Jones, for Zn-incorporated Cs2SnI6). These results will prompt research on the influence of metal ions in perovskite materials that may afford novel properties for next-generation optoelectronics.