Optical spectra and exciton radiative lifetimes in bulk transition metal dichalcogenides

Author(s)

Villegas, Cesar E. P. ; Marinho Jr, Enesio ; Venezuela, Pedro ; Rocha, Alexandre R.

• Document type: Journal article
• Source: Physical Chemistry Chemical Physics; v. 26, n. 17, p. 10-pg., 2024-04-16.

Abstract

The optical response of layered transition metal dichalcogenides (TMDCs) exhibits remarkable excitonic properties which are important from both fundamental and device application viewpoints. One of these phenomena is the observation of intralayer/interlayer excitons. While much effort has been done to characterize excitons in monolayer TMDCs and their heterostructures, a quite limited number of works have addressed the exciton spectra of their bulk counterparts. In this work, we employ ab initio many-body perturbation calculations to investigate the exciton dynamics and spectra of bulk 2H-MX2 (M = Mo, W, and X = S, Se). For molybdenum-based systems, we find the presence of interlayer excitons at energies higher than the first bright exciton (XA), with non-negligible strength intensity. Our results also show that interlayer excitons in tungsten-based systems are almost degenerate in energy with XA and possess very small oscillator strengths when compared with molybdenum-based systems. At room temperature, and considering the thermal exciton fine-structure population for the XA-exciton, we estimate effective radiative lifetimes in the range of similar to 4-14 ns. For higher energy excitons we predict longer effective lifetimes of tens of nanoseconds. Here, based on ab initio many-body perturbation calculations, we study the exciton dynamics and optical response spectra of bulk 2H-MX2 (M = Mo, W, and X = S, Se). (AU)

• FAPESP's process: 20/13172-8 - Temperature dependence of band gap in hybrid perovskites: a first-principles study
• Grantee: Enesio Marinho da Silva Jr
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/13720-8 - 2D Semiconductors for Photovoltaic Applications: Eletron-Phonon and Exciton-Phonon Coupling Effects on Carriers Lifetimes and Optical Properties
• Grantee: Alexandre Reily Rocha
• Support Opportunities: Research Grants - Visiting Researcher Grant - Brazil
• FAPESP's process: 17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties
• Grantee: Adalberto Fazzio
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 21/14335-0 - ICTP South American Institute for Fundamental Research: a regional center for Theoretical Physics
• Grantee: Nathan Jacob Berkovits
• Support Opportunities: Special Projects