Liang Guo

Here, we observed chiroptical evolution during the synthesis of perovskite nanocrystals (NCs). Using a steric-delayed nucleation strategy, we slowed the ripening of NCs and observed changes in the circular dichroism (CD) signal of perovskite NCs. Two chiroptical evolution events occurred during NC formation under different conditions, attributed to ligand displacement and NC self-assembly, respectively. Surface characterization and computational studies demonstrate that the ligands initially bind to the NC surface and dissociate during the ripening stage, offering the time window to observe and enhance the intrinsic chirality. Our findings provide a new strategy for studying and designing intrinsically chiral perovskite nanostructures.

Nanostructured dielectric optomechanical platforms have facilitated the efficient generation and precise control of hypersonic waves. However, substantial energy losses have thus far prevented the realization of nanoresonators with long-lasting signals and high quality factors. In this study, we propose suspended all-dielectric fishnet structures made of gallium phosphide, which exhibit up to five odd-order resonant modes with an exceptionally low isotropic loss factor (η = 0.01), which is 1 order of magnitude lower than conventional nanosystems. For a representative device, the quality factors reach as high as 65.48 and 90.38 for the fundamental and n = 3 resonant modes, respectively. The resonant frequencies remain unsensitive to changes in lateral geometry (e.g., hole diameters), which is attributed to the dominance of out-of-plane vibrational modes in the fishnet membrane. These results establish a foundation for integrating all-dielectric nanostructures into launching and manipulating gigahertz hypersonic waves at the nanoscale while also addressing responses of complementary structures.

0D, 1D, and 2D nanomaterials for quantum information application, showcasing their dimensional advantages in coherence, scalability, and efficient qubit manipulation.

Chiral semiconducting nanomaterials offer many potential applications in photodetection, light emission, quantum information, and so on. However, it is difficult to achieve a strong circular dichroism (CD) signal in semiconducting nanocrystals (NCs) due to the complexity of chiral ligand surface engineering and multiple, uncertain mechanisms of chiroptical behavior. Here, a chiral ligand exchange strategy with cysteine on the ternary metal chalcogenide AgBiS ₂ NCs is developed, and a strong, long‐lasting CD signal in the near‐UV region is achieved. By carefully optimizing the ligand concentration, the CD peaks are observed at 260 and 320 nm, respectively, giving insight into the different ligand binding mechanisms influencing the CD signal of AgBiS ₂ NCs. Using density‐functional theory, a large degree of crystal distortion by the bidentate mode of ligand chelation, and efficient ligand‐NC electron transfer, synergistically resulting in the strongest CD signal (g‐factor over 10 ⁻² ) observed in chiral ligand‐exchanged semiconductor NCs to date, is demonstrated. To demonstrate the effective chiral properties of these AgBiS ₂ NCs, a spin‐filter device with over 86% efficiency is fabricated. This work represents a considerable leap in the field of chiral semiconductor NCs and points toward their future applications.

Despite recent advances, it is still difficult to fabricate deep blue‐emitting perovskite light‐emitting diodes (LEDs) that are immune to the color instability caused by halide mixing. This is largely because it is still challenging to achieve bright, stable, pure bromide perovskite materials with deep blue emission. Here, a novel strategy is reported for synthesizing ultrasmall CsPbBr₃ quantum dots (QDs) under ambient conditions. Precise size control is used to tune the peak emission wavelengths, via the confinement effect, from 433 to 501 nm. These ultrasmall QDs, with sizes of 2–6 nm, exhibit ultralow trap density and stable photoluminescence quantum yields up to 94%, particularly in the deep blue spectral region (440–465 nm). QD‐LEDs fabricated with these materials achieve an external quantum efficiency of 1.0% at 459 nm. The exceptional control of the emission properties demonstrated here suggests a new strategy for building stable, efficient blue QD‐LEDs.

Advances in two-dimensional (2D) devices require innovative approaches for manipulating transport properties. Analogous to the electrical and optical responses, it has been predicted that thermal transport across 2D materials can have a similar strong twist-angle dependence. Here, we report experimental evidence deviating from this understanding. In contrast to the large tunability in electrical transport, we measured an unexpected weak twist-angle dependence of interfacial thermal transport in MoS₂ bilayers, which is consistent with theoretical calculations. More notably, we confirmed the existence of distinct regimes with weak and strong twist-angle dependencies for thermal transport, where, for example, a much stronger change with twist angles is expected for graphene bilayers. With atomic simulations, the distinct twist-angle effects on different 2D materials are explained by the suppression of long-wavelength phonons via the moiré superlattice. These findings elucidate the unique feature of 2D thermal transport and enable a new design space for engineering thermal devices.