Probing the ultrafast dynamics in nanomaterial complex systems by femtosecond transient absorption spectroscopy

Abstract

Over the past decade the integration of ultrafast spectroscopy with nanoscience has greatly propelled the development of nanoscience, as the key information gleaned from the mechanistic studies with the assistance of ultrafast spectroscopy enables a deeper understanding of the structure-function interplay and various interactions involved in the nanosystems. This mini-review presents an overview of the recent advances achieved in our ultrafast spectroscopy laboratory that address the ultrafast dynamics and related mechanisms in several representative nanomaterial complex systems by means of femtosecond time-resolved transient absorption spectroscopy. We attempt to convey instructive, consistent information regarding the important processes, pathways, dynamics, and interactions involved in the nanomaterial complex systems, most of which exhibit excellent performance in photocatalysis.

Ce3+-Doping to Modulate Photoluminescence Kinetics for Efficient CsPbBr3 Nanocrystals Based Light-Emitting Diodes

“…In an attempt to understand the mechanism responsible for the Ce 3+ -doping-induced PLQY enhancement effect in CsPbBr 3 NCs, we carried out femtosecond (fs) time-resolved transient absorption (TA) spectroscopy characterizations to track in real time the ultrafast exciton dynamics ,− in a representative doped sample (2.88% in terms of Ce/Pb ratio, or 30% in terms of CeBr 3 ratio) in reference to the undoped one. In the fs-TA measurements, we adopted a pump–probe configuration featuring a UV pump (320 nm) and a white-light-continuum probe (430–620 nm) (Experimental Section).…”

Optically Switchable Photocatalysis in Ultrathin Black Phosphorus Nanosheets

“…Naturally, it can be expected that the photoexcited electron dynamics occurring in the two subband systems may differ from each other. With this in mind, we further interrogated the BP nanosheets by femtosecond time-resolved transient absorption (TA) spectroscopy, an effective tool for tracking the real-time ultrafast relaxation kinetics in nanomaterials. − Herein, a pump–probe configuration featuring UV–vis pump and white-light continuum probe was employed in our TA measurements. We selected two sets of pump wavelengths, that is, 530 and 600 nm for the visible-light excitation while 330 and 400 nm for the UV-light excitation.…”

In situ charge carrier dynamics of semiconductor nanostructures for advanced photoelectrochemical and photocatalytic applications

“…Direct comparison of the variance of carrier concentration in a specific pathway is possible by simply evaluating the amplitude contribution of the TA component. There are four probable mechanisms accountable for different ΔA behaviors, which include ground state bleaching (GSB), stimulated emission (SE), excited state absorption (ESA) and product absorption (PA) [35,36]. As displayed in Figure 1D, GSB originates from the reduced number of charge carriers in the ground state for the excited samples.…”