Density Functional Theory Analysis of Alq and Gaq Derivatives: Structural Optimization and Electronic Properties for Organic Light-Emitting Diode Applications.

This study employs computational quantum mechanics to investigate the impact of molecular and electronic structures on the optical properties of organic light-emitting diodes (OLEDs). First-principles calculations based on density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were used to analyze Mq3 and Mq2p (M = Al or Ga) and their derivatives, where one quinoline ligand was replaced with picolinate and CH/N substitutions were introduced in the qa and qc ligands. The molecular structures were optimized using time-independent DFT, while electronic excitation energies were determined using time-dependent DFT. Based on the optimized ground-state structures, key molecular properties, including bond length, bond angle, dipole moment, band gap, electron cloud energies, ionization energy, electron affinity, and reorganization energy, were systematically computed. Additionally, absorption and emission spectra were examined, revealing tunable Stokes shifts. The results indicate that Gaq derivatives exhibit superior structural stability and improved hole-blocking and electron injection capabilities compared to Alq. These findings offer valuable guidance for designing superior OLED materials, potentially enhancing light emission and electronic transport.