Graphdiyne: A promising nonlinear optical material modulated by tetrahedral alkali-metal nitrides

A new series of the functionalized graphdiyne (GDY) material was designed by adsorbing the tetrahedral Li3NM molecules on the largely delocalized pi-conjugated GDY surface, namely Li3NM@GDY (M = Li, Na, K), and its structure, chemical stability, electronic property, and the first hyperpolarizability were investigated by using the density functional theory computations. Our results reveal that the Li3NM molecules can interact with three triangular holes on the GDY surface, in which the van der Waals interactions play a crucial role in enhancing the structural stability. Meanwhile, the total NPA charges on the Li3NM molecules are gradually increased from Li to K, and the Li3NM molecules can transfer an electron to GDY, forming intramolecular electron donor and acceptor pairs. All of studied complexes exhibit the giant static first hyperpolarizabilities (beta(tot)), up to similar to 2.88 x 10(5) a.u. for Li3NK@GDY, which can be explained by two-level expression from the TDDFT calculations. This study will inevitably stimulate further synthesis of the novel graphdiyne-based nonlinear optical materials. (C) 2018 Elsevier B.V. All rights reserved.