Trion formation resolves observed peak shifts in the optical spectra of transition metal dichalcogenides

Abstract

Monolayer transition metal dichalcogenides (TMDs) have the potential to unlock novel photonic and chemical technologies if their optoelectronic properties can be understood and controlled. Yet, recent work has offered contradictory explanations for how TMD absorption spectra change with carrier concentration, fluence, and time. Here, we test our hypothesis that the large broadening and shifting of the strong band-edge features observed in optical spectra arise from the formation of negative trions. We do this by fitting an ab initio based, many-body model to our experimental electrochemical data. Our approach provides an excellent, global description of the potential-dependent linear absorption data. We further leverage our model to demonstrate that trion formation explains the non-monotonic potential dependence of the transient absorption spectra, including through photoinduced derivative lineshapes for the trion peak. Our results motivate the continued development of theoretical methods to describe cutting-edge experiments in a physically transparent way.

5 pages, 5 figures main text. 4 pages, 6 figures, several passages of pseudocode SI, 66 references

References in corpus (14)

• Ultrafast Charge Transfer in Atomically Thin MoS2/WS2 Heterostructures
• Observation of giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor
• Trion induced negative photoconductivity in monolayer MoS2
• Electronic Structure of Epitaxial Single-Layer MoS${}_2$
• Direct Determination of Band Gap Renormalization in Photo-Excited Monolayer MoS2
• Ultrafast charge-transfer dynamics in twisted MoS${}_2$/WSe${}_2$ heterostructures
• Exciton-polaron interactions in monolayer WS${}_2$
• Ground and Excited Exciton Polarons in Monolayer MoSe2
• Relaxation and darkening of excitonic complexes in electrostatically-doped monolayer semiconductors: Roles of exciton-electron and trion-electron interactions
• Quantum Dynamics of Attractive and Repulsive Polarons in a Doped MoSe${}_2$ Monolayer
• Many-body theory of optical absorption in doped two-dimensional semiconductors
• Hot carrier extraction from 2D semiconductor photoelectrodes
• Light-matter coupling and non-equilibrium dynamics of exchange-split trions in monolayer WS2
• Doping-induced non-Markovian interference causes excitonic linewidth broadening in monolayer WSe${}_2$