A Roadmap to Decipher Ultrafast Photophysics in Two-Dimensional Nanomaterials

TL;DR

This paper provides a comprehensive roadmap for analyzing complex transient absorption data in 2D nanomaterials, combining qualitative and quantitative methods to better understand their ultrafast photophysical behavior.

Contribution

It introduces a systematic approach to deconvolute congested TA spectra in 2D materials, enhancing interpretation of their nonlinear optical responses.

Findings

Effective spectral deconvolution techniques demonstrated

Enhanced understanding of many-body interactions in 2D semiconductors

Guidelines for combining qualitative and quantitative analysis provided

Abstract

Atomically thin two-dimensional (2D) semiconductors are extensively investigated for opto-electronic applications that require strong light-matter interactions. In view of such applications, it is essential to understand how (photo)excitation alters the non-linear optical response of these materials under high carrier density conditions. Broadband transient absorption (TA) spectroscopy is by now a widely used tool to study semiconductor physics in such highly excited systems. However, the complex interplay between different many-body interactions in 2D materials produces highly congested spectral information and an ensuing non-trivial nonlinear photo-response, thereby masking the desired intrinsic photophysics. Herein, we outline a concise roadmap for analyzing such congested datasets based on examples of TA analysis of various 2D materials. In particular, we emphasize the synergy between an initial qualitative understanding of the transient photo-response based on line shapes and their derivatives, and a consequent quantitative spectral deconvolution backed by such insights.