Unveiling Long-Lived Hot-Electron Dynamics via Hyperbolic Meta-antennas

Conventional plasmonic nanoantennas enable scattering and absorption bands at the same wavelength region, making their utilization to full potential impossible for both features simultaneously. Here, we take advantage of spectrally separated scattering and absorption resonance bands in hyperbolic meta-antennas (HMA) to enhance the hot-electron generation and prolong the relaxation dynamics of hot carriers. First, we show that HMA enables extending plasmon-modulated photoluminescence spectrum toward longer wavelengths due to its particular scattering spectrum, in comparison to the corresponding nanodisk antennas (NDA). Then, we demonstrate that the tunable absorption band of HMA controls and modifies the lifetime of the plasmon-induced hot electrons with enhanced excitation efficiency in the nearinfrared region and also broadens the utilization of the visible/NIR spectrum in comparison to NDA. Thus, the rational heterostructures designed by plasmonic and adsorbate/dielectric layers with such dynamics can be a platform for optimization and engineering the utilization of plasmon-induced hot carriers.

Automated summary

Conventional plasmonic nanoantennas cannot fully exploit their scattering and absorption features simultaneously due to their overlap in the same wavelength region. However, hyperbolic meta-antennas (HMA) with spectrally separated scattering and absorption bands enable enhanced hot-electron generation and prolonged relaxation dynamics of hot carriers. By extending the plasmon-modulated photoluminescence spectrum towards longer wavelengths and controlling the tunable absorption band, HMA offers improved excitation efficiency and broader utilization of visible/NIR spectrum compared to nanodisk antennas (NDA). Therefore, rational heterostructures designed with plasmonic and adsorbate/dielectric layers in such dynamics can optimize and engineer the utilization of plasmon-induced hot carriers.