Luminescent Compounds fac- and mer-Aluminum Tris(quinolin-8-olate). A Pure and Hybrid Density Functional Theory and Time-Dependent Density Functional Theory Investigation of Their Electronic and Spectroscopic Properties

Abstract

Density functional theory and time-dependent density functional theory have been applied to describe the ground and excited states and the spectral characteristics of the meridianal and facial isomers of aluminum tris(quinolin-8-olate) (Alq3). Vertical absorption wavelengths and oscillator strengths of both meridianal Alq3 and facial Alq3 have been computed up to about 255 nm (4.86 eV) and compared with experimental data. Experimental meridianal Alq3 absorption band locations are well reproduced by the computations, allowing easy assignment of the absorption bands. The facial Alq3 absorption spectrum has been computed, and a detailed comparison of the excited state characteristics of the two isomers has been addressed for pointing out differences in absorption and emission properties. This work suggests that the facial Alq3 may be the constituent of the recently reported Alq3 crystalline phase known as the δ-phase. This is an important new material for understanding the Alq3 solid-state properties and for...