Probing 2D Exciton Dynamics of Non-Hydrogenic Anisotropic Rydberg Spectra in Anomalous Screening Regime

Abstract

Understanding of the excitonic perspective on light-driven energy conversions is limited, particularly in higher excited states of excitons in 2D systems arising from nonlocal screening effects. Besides, the anisotropy in the sequence of excited exciton states (Rydberg Spectra) has been completely overlooked in the literature. This work presents a theoretical investigation of the anisotropic non-hydrogenic exciton dynamics in blue-AsP, systematically exploring the origin of the deviation from the conventional hydrogenic Rydberg series. A key insight from our investigation underscores the profound influence of the principal quantum number on effective dielectric screening when probing the binding energies in the Rydberg spectra of excited excitonic states (ns = 1s,2s,3s,...). This study also offers a much-needed systematic comparison between the non-hydrogenic analytical models, complemented by G 0 W 0 + BSE methodology. Importantly, this highlights the exciting possibility of precisely controlling exciton behavior through strategic substrate selection. Our findings extend the anisotropic Rydberg spectra to the "anomalous screening regime" in both armchair and zigzag directions.