Exciton-surface plasmon polariton interactions

Abstract

Exciton-surface plasmon polariton (exciton-SPP) interactions in semiconductor-metal hybrid nanostructures connect two fundamentally different quantum mechanical excitations with strikingly different dispersion relations and optical response. The main focus in investigating these light-matter interactions and nanostructures is to control the light via light on the nanometric length scale and ultrafast timescale, not achievable by present photonic or electronic technologies. Here, we provide a concise description of the relevant background physics and an overview of the manifestations, challenges and applications of weak and strong exciton-SPP interactions. It is now well established that semiconductor-metal hybrid nanostructures offer exciting opportunities to investigate intriguing quantum phenomena and many-body interactions in condensed matter systems even at room temperature. We also review how exciton-SPP interactions have been influencing various research directions. It is amply evident that a comprehensive understanding of these interactions may play an important role in several research areas. The recent progress made in this field is expected to give rise to novel applications of active plasmonic structures. Synopsis:The ability of surface plasmon polaritons to localize light on the nanoscale dimensions results in a strong field ARTICLE HISTORY

Charting the Exciton–Polariton Landscape of WSe2 Thin Flakes by Cathodoluminescence Spectroscopy

“…[31] In addition, plasmon polariton dispersion and mode volume can be further controlled by structuring the materials or using metamaterials, which further affects the dispersion of the excited polaritons and the strongcoupling effects. [32][33][34] However, plasmons themselves suffer from DOI: 10.1002/adpr.202100124 Semiconducting transition-metal dichalcogenides (TMDCs) provide a fascinating discovery platform for strong light-matter interaction effects in the visible spectrum at ambient conditions. While most of the works have focused on hybridizing excitons with resonant photonic modes of external mirrors, cavities, or nanostructures, intriguingly, TMDC flakes of subwavelength thickness can themselves act as nanocavities.…”

Relaxation and Excitation Rate Modifications by Metal Nanostructures for Solar Energy Conversion Applications

“…The longitudinal mode occurs at 612 nm (3:1) and 553 nm (3:2), whereas the transverse mode for both aspect ratios occurs at ∼503 nm. [5][6][7]18,24 For nanospheres, two modes are degenerate occurring at 512 nm. The scattering efficiency is higher for the longitudinal mode and hence results in a larger extinction coefficient.…”

“…For example, though improved energy conversion efficiency is attributed mainly to higher absorption by an active layer due to the extreme light concentration, these structures are also responsible for enhancing radiative relaxation due to emitterplasmon coupling besides resonator effects leading to shorter carrier lifetimes and higher luminescence losses, which are disadvantageous for boosting conversion efficiency of photovoltaics. [5][6][7]17 Thus, the conversion efficiency depends on a variety of factors, and therefore, detailed investigations of field confinement and relaxation rate modifications associated with metal nanostructures play a key role in the ability to increase the overall efficiency of solar energy conversion applications.…”

“…The ability of metal nanostructures to concentrate and guide light on the nanometric length scale has led to their use in a wide range of applications such as sensing, surface enhanced Raman spectroscopy, and light harvesting assemblies for solar energy conversion. , This unique property of metal nanostructures originates from hybrid modes of free electron oscillations in metals coupled to light waves, which can be laterally confined on the nanoscale. − Over the past decade, there has been tremendous progress in designing and developing various nanostructures supporting localized surface plasmon resonances (LSPRs) as well as propagating surface plasmon polaritons (SPPs). − The usage of these nanostructures in solar energy conversion applications relies on electromagnetic field confinement resulting in enhanced light-localization, scattering, absorption, and luminescence yield. Additionally, investigations of modifications in relaxation dynamics involving weak and strong dipole interactions with plasmonic resonators have also attracted increased attention. − In particular, the role of metal nanoparticles in luminescent solar concentrators − and in boosting the light harvesting in an active layer of organic and perovskite photovoltaic devices − is noteworthy. Incorporation of plasmonic structures is expected to reduce the device volume and weight, potentially yielding efficient low-cost solar energy conversion solutions.…”

“…Though plasmonic structures are expected to enhance the efficiency of the energy conversion processes, some of the benefits occur at the expense of others. For example, though improved energy conversion efficiency is attributed mainly to higher absorption by an active layer due to the extreme light concentration, these structures are also responsible for enhancing radiative relaxation due to emitter-plasmon coupling besides resonator effects leading to shorter carrier lifetimes and higher luminescence losses, which are disadvantageous for boosting conversion efficiency of photovoltaics. − , Thus, the conversion efficiency depends on a variety of factors, and therefore, detailed investigations of field confinement and relaxation rate modifications associated with metal nanostructures play a key role in the ability to increase the overall efficiency of solar energy conversion applications. Here, we present a detailed investigation of parameter space for three different gold nanostructures, namely nanospheres, nanorods, and slot antennas, to identify the regions of optimum performance.…”