Quantum chemical analysis of salen–aluminum complexes for organic light emitting diodes

•Emitting properties of salen–Al complexes are important for application in organic light emitting diodes.•The first excited-state structures and their emission energies were calculated.•We rectify the problem of TD-B3LYP by employing the long-range corrected TD-CAM-B3LYP.•TD-CAM-B3LYP structures and their transition energies well explain experimental results.