Investigation of the electronic and optical properties of Al13–dianhydride complexes by (time-dependent) density functional theory

Abstract

The electronic and nonlinear optical (NLO) properties of Al₁₃–X and 2Al₁₃–X (where X represents dianhydrides BPDA, BTDA, ODPA, and 6FDA) were systematically investigated using (time-dependent) density functional theory methods. It was found that Al₁₃ could effectively bind to dianhydride molecules via two strong Al–O bonds with high binding energies. Compared to pristine Al₁₃ and dianhydrides, hybridized complexes Al₁₃–X exhibit significant enhancements in both linear and nonlinear optical response properties, as evidenced by the calculated isotropic polarizability and static/dynamic first hyperpolarizabilities, respectively. The nature of the large first hyperpolarizabilities of Al₁₃–X complexes can be understood by analyzing the low excitation energies of the key excited states and the first hyperpolarizability density. Furthermore, the dianhydride ligand is capable of bridging two aluminum clusters to form a novel D–A–D molecule, which further enhances the NLO properties of the molecules. It is hoped that the current research work will provide ideas for the rational design of such inorganic–organic hybrid complexes as novel functional electro-optical materials.