Nano Letters最新文献

Developing optoelectronic synaptic devices with low power consumption, broadband response, and biological compatibility is crucial to simulate the functions of optic nerve. Here, an organic synapse transistor based on C8-BTBT/PMMA/PbS quantum dots (PbS QDs) is fabricated, which has good stability, low power consumption (as low as 0.49 fJ per event under 800 nm near-infrared optical pulse), and broadband response from ultraviolet to near-infrared wavelengths. Based on the trap and release of photogenerated carriers by PbS QDs, a series of synaptic behaviors are simulated by the device. Furthermore, we use artificial neural network as the model to realize the recognition of facial feature image in the broad spectral range; the recognition rate reached 96.25% (350 nm ultraviolet), 92.14% (580 nm visible), and 90.03% (800 nm near-infrared). This work is beneficial for advancing the development of future artificial intelligence vision sensing.

Two-dimensional (2D) materials have emerged as promising candidates for next-generation integrated single-photon emitters (SPEs). However, significant variability in the emission energies presents a major challenge in producing identical single photons from different 2D SPEs, which may become crucial for practical quantum applications. Although various approaches to dynamically tuning the emission energies of 2D SPEs have been developed to address the issue, the practical solution to matching multiple individual 2D SPEs is still scarce. In this work, we demonstrate precise emission energy tuning of individual SPEs in a WSe₂ monolayer. Our approach utilizes localized strain fields near individual SPEs, which we control by adjusting the volume of a stressor layer through laser annealing. This technique allows continuous emission energy tuning of up to 15 meV while maintaining the qualities of SPEs. Additionally, we showcase the precise spectral alignment of three distinct SPEs in a single WSe₂ monolayer to the same wavelength.

Fast-emitting scintillators are essential for advanced diagnostic techniques, yet many suffer from low radiation attenuation. This trade-off is particularly pronounced in polymer scintillators, which, despite their fast emission, exhibit low density and low atomic numbers, limiting the radiation attenuation factor, resulting in low detection efficiency. Here, we overcome this limitation by creating a heterostructure scintillator of alternating nanometric layers, combining fast light-emitting polymer scintillator layers and transparent stopping layers with a high radiation attenuation factor. The nanolayer thicknesses are tuned to optimize the penetration depth of recoil electrons in active emissive layers, maximizing the conversion of X-rays to visible light. This design increases light output by up to 1.5 times and enhances imaging resolution by a factor of 2 compared to homogeneous polymer scintillators due to the ability to use thinner samples. These results demonstrate the potential of heterostructure scintillators as next-generation detector materials, overcoming the limitations of homogeneous scintillators.

In order to study the catalytic behavior of a metastable-phase catalyst in electrocatalytic hydrogenation, we report a new metastable-phase noble-metal-free core-shell catalyst with a metastable hexagonal closest packed (hcp) phase Ni as the shell and face-centered-cubic (fcc) phase Cu as the core (Cu@hcp Ni NPs) for electrocatalytic hydrogenation of nitrobenzene (Ph-NO₂) to aniline (Ph-NH₂). Using H₂O as the hydrogen source, it achieves up to 99.63% Ph-NO₂ conversion and ∼100% Ph-NH₂ selectivity, with an improved activity turnover frequency (TOF: 6640 h^-1), much higher than those of hcp Ni NPs (5183.7 h^-1) and commercial Pt/C (3537.6 h^-1). It can also deliver a variety of aminoarenes with outstanding selectivity and excellent functional group compatibility with several groups. Mechanistic studies have shown that the introduction of Cu enhances hcp Ni's ability to dissociate water in situ to produce H* and improves the hydrogenation rate, resulting in the rapid conversion of Ph-NO₂ to the final product Ph-NH₂.