Hot electron dynamics and relaxation in hyperbolic meta-antennas

TL;DR

This paper demonstrates how hyperbolic meta-antennas can independently tune scattering and absorption, enhancing hot electron generation and dynamics, which broadens applications in hot-carrier photochemistry and optoelectronics.

Contribution

It introduces hyperbolic meta-antennas with separated spectral bands for scattering and absorption, enabling improved hot electron manipulation compared to traditional plasmonic nanoantennas.

Findings

Extended photoluminescence spectrum in HMA due to scattering properties

Enhanced hot electron excitation efficiency in NIR in HMA

Broader spectral range for hot-carrier applications in HMA

Abstract

Conventional plasmonic nanoantennas enable scattering and absorption bands at the same wavelength region, making their utilization to full potential impossible for both features simultaneously. In this regard, hyperbolic meta-antennas (HMA) offer independent, tunable and separate scattering and absorption resonance bands at different spectral ranges. Here, we take advantage of these separated spectral bands in HMA to enhance and modify the hot electron-based phenomena. On the one hand, we observed the photoexcited emission of particle plasmons by hot carriers; on the other, we utilized ultrafast transient absorption spectroscopy to characterize the dynamics of hot electrons. Compared to corresponding plasmonic nanodisk antennas (NDA), extended plasmon-modulated photoluminescence (PM-PL) spectrum in HMA is achieved, attributing to their particular scattering spectra. Furthermore, the absorption band at longer wavelengths in HMA enhances the excitation efficiency of plasmon-induced hot electrons (HEs) in the near-infrared region (NIR) with an extended lifetime. It broadens the utilization of the visible/NIR range that can not be observed in conventional NDAs. Our results further show that such meta-antennas can generate plasmon-induced hot carriers on demand and provide insight into the optimization and engineering of the hot-carrier-assisted photochemistry.