Ultrafast optical spectroscopy of semiconducting and plasmonic nanostructures and their hybrids

TL;DR

This paper reviews ultrafast optical spectroscopy studies on nanostructures and their hybrids, focusing on carrier dynamics, plasmonic responses, and mechanisms enhancing photocatalytic efficiency.

Contribution

It provides a comprehensive overview of recent ultrafast spectroscopy investigations on various nanostructures and their hybrid systems, highlighting new insights into their dynamic processes.

Findings

Plasmonic responses depend on nanoparticle shape and environment.

Hot-carrier dynamics are crucial in perovskites and semiconductor nanowires.

Charge transfer mechanisms enhance hybrid nanostructure functionalities.

Abstract

The knowledge of the carrier dynamics in nanostructures is of fundamental importance for the development of (opto)electronic devices. This is true for semiconducting nanostructures as well as for plasmonic nanoparticles (NPs). Indeed, improvement of photocatalytic efficiencies by combining semiconductor and plasmonic nanostructures is one of the reasons why their ultrafast dynamics are intensively studied. In this work, we will review our activity on ultrafast spectroscopy in nanostructures carried out in the recently established EuroFEL Support Laboratory. We have investigated the dynamical plasmonic responses of metal NPs both in solution and in 2D and 3D arrays on surfaces, with particular attention being paid to the effects of the nanoparticle shape and to the conversion of absorbed light into heat on a nano-localized scale. We will summarize the results obtained on the carrier dynamics in nanostructured perovskites with emphasis on the hot-carrier dynamics and in semiconductor nanosystems such as ZnSe and Si nanowires, with particular attention to the band-gap bleaching dynamics. Subsequently, the study of semiconductor-metal NP hybrids, such as CeO$_2$-Ag NPs, ZnSe-Ag NPs and ZnSe-Au NPs, allows the discussion of interaction mechanisms such as charge carrier transfer and F{\"o}rster interaction. Finally, we assess an alternative method for the sensitization of wide band gap semiconductors to visible light by discussing the relationship between the carrier dynamics of TiO$_2$ NPs and V-doped TiO$_2$ NPs and their catalytic properties.