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Plasmonic nanostructures as narrowband perfect absorbers have garnered significant attention due to their potential applications in biosensing and environment detection. This study emphasizes the investigation of arrayed split ring nanostructures within the configuration of metal-insulator-metal (MIM) multilayers, resulting in a maximum light absorption of 99.94% in the near-infrared (NIR) spectral range. The exceptional absorption efficiency of the device is attributed to the strong resonance of electric and magnetic fields arising from the Fabry–Pérot cavity resonance. The resonant peak can be flexibly tuned by engineering the dielectric layer thickness, the period, and the geometric parameter of split rings. Remarkably, the device exhibits promising capabilities in sensing, demonstrating a sensitivity of 326 nm/RIU in visible wavelengths and 504 nm/RIU in NIR wavelengths when exposed to bio-analytes with varying refractive indices. This designed nanostructure can serve as a promising candidate for biosensors or environmental detection. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures have been regarded as potential candidates for boosting the nonlinear up-conversion rate at the nanoscale level due to their strong near-field enhancement and inherent high design freedom. Here, we design a hybrid metasurface to realize the moderate interaction of Fano resonance and create the dual-resonant mode-matching condition to facilitate the nonlinear process of second harmonic generation (SHG). The hybrid metasurface presents dipolar and octupolar plasmonic modes near the fundamental and doubled-frequency wavelengths, respectively, further utilized to enhance the SHG of low-dimensional MoS2 semiconductors. The maximum intensity of SHG in hybrid metasurface coupled MoS2 is more than ten thousand times larger than that of other structure-units coupled MoS2. The conversion efficiency is reported to be as high as 3.27 × 10−7. This work paves the way to optimize nonlinear light–matter interactions in low-dimensional structures coupled with semiconductors. [ABSTRACT FROM AUTHOR]

Optoelectronic synaptic elements are emerging functional devices for the vigorous development of advanced neuromorphic computing technology in the post-Moore era. However, optoelectronic devices based on transition metal dichalcogenides (TMDs) are limited to their poor mobilities and weak light-matter interactions, which still hardly exhibit superior device performances in the application of artificial synapses. Here, we demonstrate the successful fabrication of Au nanoparticle-coupled MoS2 heterostructures via chemical vapor deposition (CVD), where the light absorption of MoS2 is greatly enhanced and engineered by plasmonic effects. Hot electrons are excited from Au nanoparticles, and then injected into MoS2 semiconductors under the light illumination. The plasmonically-engineered photo-gating effect at the metal-semiconductor junction is demonstrated to create optoelectronic devices with excellent synaptic behaviors, especially in ultra-sensitive excitatory postsynaptic current (EPSC, 9.6 × 10−3 nA@3.4 nW·cm−2), ultralow energy consumption (34.7 pJ), long-state retention time (> 1,000 s), and tunable synaptic plasticity transitions. The material system of Au-nanoparticles coupled TMDs presents unique advantages for building artificial synapses, which may lead the future development of neuromorphic electronics in optical information sensing and learning. [ABSTRACT FROM AUTHOR]

2D transition metal dichalcogenides are becoming attractive materials for novel photoelectric and photovoltaic applications due to their excellent optoelectric properties and accessible optical bandgap in the near-infrared to visible range. Devices utilizing 2D materials integrated with metal nanostructures have recently emerged as efficient schemes for hot electron-based photodetection. Metal-semiconductor heterostructures with low cost, simple procedure, and fast response time are crucial for the practical applications of optoelectric devices. In this paper, template-based sputtering method is used first to fabricate Au nanoantenna (NA)/MoS2 heterostructures with low cost, simple preparation, broad spectral response, and fast response time. Through the measurement of femtosecond pump-probe spectroscopy, it is demonstrated that plasmon-induced hot electron transfer takes place in the Au NA/MoS2 heterostructure on the order of 200 fs with an injected electron density of about 5.6 × 1012 cm−2. Moreover, the pump-power-dependent photoluminescence spectra confirm that the exciton energy of MoS2 can be enhanced, coupled, and reradiated by the Au NA. Such ultrafast plasmon-induced hot electron transfer in the metal-semiconductor heterostructure can enable novel 2D devices for light harvesting and photoelectric conversion. [ABSTRACT FROM AUTHOR]

On page 6394, Z. Y. Fang and co‐workers apply a femtosecond pumping‐probe technique to measure electron transfer of synthesized AU nanoantenna (NA)/MoS2 heterostructures. The results indicate an ultrafast optical response time and a high cutoff frequency for devices based on this heterostructure. Combining the optoelectric properties of MoS2 with the plasmonic properties of Au NAs holds great promise for photodetectors and photovoltaics. [ABSTRACT FROM AUTHOR]