Interlayer Excitons and Radiative Lifetimes in MoSe₂/SeWS Bilayers: Implications for Light-Emitting Diodes

Author(s)

Narciso Pedrosa, Renan ; Villegas, Cesar E. P. ; Reily Rocha, Alexandre ; Amorim, Rodrigo G. ; Scopel, Wanderla

• Document type: Journal article
• Source: ACS APPLIED NANO MATERIALS; v. 8, n. 10, p. 8-pg., 2025-03-03.

Abstract

Interlayer excitons, formed by electrical charge transfer between layers of 2D van der Waals heterostructures, are of the utmost importance for light-detection and light-harvesting applications. In particular, Janus-based heterostructures are promising platforms to observe robust interlayer exciton dynamics due to their intrinsic electric field. Here, we carry out ground- and excited-state first-principles calculations, based on the G(0)W(0) approach and the solution of the Bethe-Salpeter equation, to investigate the energetic, electronic, and excitonic properties of MoSe2/WSSe van der Waals heterobilayers. Our results show that the heterojunction presents features of type-II band alignment and tightly bound, long-lived interlayer excitons. Indeed, the lowest dipole-allowed excitonic state possesses an interlayer character and a slight deviation of 12% in its binding energy compared to the lowest-energy intralayer exciton. Furthermore, the interlayer excitons have transition rates similar to 55 times smaller than the intralayer ones, which translates into a longer radiative lifetime of dozens of nanoseconds at room temperature. This is up to 2 orders of magnitude greater than that of the lowest-energy intralayer exciton. The findings emphasize the critical role of Janus-based heterojunctions in influencing interlayer exciton radiative lifetimes, indicating that the system possesses considerable potential for application in optoelectronic devices such as a light-emitting diode (LED) or photodetector. (AU)

• 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
• FAPESP's process: 23/09820-2 - Materials by design: from quantum materials to energy applications
• Grantee: Gustavo Martini Dalpian
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 23/11751-9 - Machine learning systems under the influence of an external bias: introducing potentiostat models in neural network molecular dynamics simulations
• Grantee: Alexandre Reily Rocha
• Support Opportunities: Scholarships abroad - Research