Giant first hyperpolarizabilities of donor–acceptor substituted graphyne: An ab initio study

•Phenomenal nonlinear optical material was proposed theoretically using graphyne motif.•Such a small molecule shows a large static first hyperpolarizability (βtot) around 128 × 10− 30 esu.•Suitable donor, acceptor choice and their separation was found to play the key role in the improvement of βtot value.

Graphyne (Gy), a theoretically proposed material, has been utilized, for the first time, in a phenomenal donor–Gy–acceptor (D–Gy–A) structure to plan a superior nonlinear optical material. Owing to the extraordinary character of graphyne, this conjugate framework shows strikingly extensive static first hyperpolarizability (βtot) up to 128 × 10− 30 esu which is an enormous improvement than that of the bare graphyne. The donor–acceptor separation plays a key role in the change of βtot value. The π-conjugation of graphyne backbone has spread throughout some of the D–A attached molecules and leads to a low band gap state. Finally, two level model clarifies that the molecule having low transition energy should have high first hyperpolarizability.

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