Lead-free double perovskite phosphors are promising alternatives to lead halide perovskites for wide uses in optoelectronic applications, but suffer from a low quantum efficiency. Here, we propose to enhance the quantum efficiency of orange-emitting Cs 2 Ag 0.4 Na 0.6 InCl 6 :Bi via a codoping strategy. The internal quantum efficiency of Cs 2 Ag 0.4 Na 0.6 InCl 6 :1% Bi phosphor was increased from 89.9% to the record 98.4 and 98.6% by codoping with 1% Ni and 1% Ce, respectively. High-level density functional theory calculations have revealed that the enhanced efficiency is ascribed to the formation of shallow trap states by codoping with Ce, while codoping with Mn can create delocalized deep traps that decrease the quantum efficiency. By applying the (Bi,Ce)-codoped sample together with a blue BaMgAl 10 O 17 :Eu 2+ phosphor, a white light-emitting diode with an excellent color rendering index of 95.7 and a correlated color temperature of 4430 K has been demonstrated. The developed Cs 2 Ag 0.4 Na 0.6 InCl 6 :Bi,Ce phosphor shows a great potential as downconversion luminescent material in solid-state lighting for general illumination.

The discovery of atomically thin van der Waals magnets (e.g., CrI3 and Cr2Ge2Te6) has triggered a renaissance in the study of two-dimensional (2D) magnetism. Most of the 2D magnetic compounds discovered so far host only one single magnetic phase unless the system is at a phase boundary. In this work, we report the near degeneracy of magnetic phases in ultrathin chromium telluride (Cr2Te3) layers with strong perpendicular magnetic anisotropy highly desired for stabilizing 2D magnetic order. Single-crystalline Cr2Te3 nanoplates with a trigonal structure (space group P3̅1c) were grown by chemical vapor deposition. The bulk magnetization measurements suggest a ferromagnetic (FM) order with an enhanced perpendicular magnetic anisotropy, as evidenced by a coercive field as large as ∼14 kOe when the field is applied perpendicular to the basal plane of the thin nanoplates. Magneto-optical Kerr effect studies confirm the intrinsic ferromagnetism and characterize the magnetic ordering temperature of individual nanoplates. First-principles density functional theory calculations suggest the near degeneracy of magnetic orderings with a continuously varying canting from the c-axis FM due to their comparable energy scales, explaining the zero-field kink observed in the magnetic hysteresis loops. Our work highlights Cr2Te3 as a promising 2D Ising system to study magnetic phase coexistence and switches for ultracompact information storage and processing.

Cancer has become a major killer threatening human health in today's society, and surface enhanced Raman spectroscopy (SERS) may provide a competitive choice for the sensitive detection of cancer‐related miRNAs. In this work, a synergistic calibrated SERS strategy based on MXene/molybdenum disulfide (MoS2)@Au nanoparticles (AuNPs) with controllable morphology is suggested for the ultrasensitive detection of miRNA‐182 by selecting the average intensity of its three own characteristic Raman peaks (at 382 cm−1 and 402 cm−1 corresponding to MoS2 and at 611 cm−1 corresponding to MXene) as a benchmark instead of additional beacon molecules. The linear goodness of fit (the determination coefficient R2) for this strategy is available in amounts up to 0.9995, which is significantly higher than that of single or double peak calibrated case, and thus improves the detection accuracy dramatically. Meanwhile, vertical MoS2 nanosheets anchored on layered MXene can provide uniformly ordered sites for accommodating suitably sized AuNPs as “hot spots” with controllable particle gap of 2.2 nm, resulting in the maximum amplified SERS signal at 1362 cm−1 generated by hairpin probe DNA with Cy5. A linear detection window from 10 am to 1 nm with an ultralow detection limit of 6.61 am for miRNA‐182 is achieved.

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