Enhancement of Non Linear Optical (NLO) responses of Germanium Doped Graphdiyne modulated by Superalkali clusters

Abstract

Functionalized graphdiyne (GDY) structures doped with Germanium atoms and adsorbed with AM3O units (AM = Li, Na, K) have been studied using DFT calculations to explore their NLO properties as potential optical materials. The AM3O units exhibit strong interactions with GeGDY clusters, evidenced by the large binding energies, particularly for the Li-adsorbed complex (-3.06 eV), while K3O-adsorbed Ge-GDY is stabilized by van der Waals interactions. The HOMO-LUMO gaps were 0.506 eV, 0.437 eV, and 0.231 eV for Li3O@Ge-GDY, Na3O@GeGDY, and K3O@Ge-GDY, respectively. Additionally, superalkali adsorption on Ge-doped GDY reduces the H-L gap across all complexes. Results show that AM3O adsorption onto Ge-GDY significantly lowers the vertical ionization potential (VIP), with intramolecular charge transfer playing a key role in the nonlinear optical (NLO) properties. Notably, the doped complexes exhibit exceptional NLO responses, with first hyperpolarizability values ranging from 2.83 ×104 au to 5.39 ×106 au, compared to pure graphdiyne. In conclusion, AM3O adsorption onto GeGDY optimizes the NLO response of GDY-based materials provides a foundation for future research aimed at further modifications and practical applications, leveraging these insights to develop materials with tailored optical characteristics for cutting-edge technologies.