Molecular structures, molecular orbital characteristics, and electronic properties of salen-aluminum complexes in organic light emitting diodes have been investigated by quantum chemical calculations to elucidate emission properties. The first excited-state structures were optimized by CIS and TD-CAM-B3LYP and their emission wavelengths were obtained from TD-CAM-B3LYP. Absorption and emission wavelengths from TD-CAM-B3LYP reproduced experimental values. The TD-B3LYP method is not adequate to calculate the transition energies for the first excited-state of salen-aluminum complexes. The structural changes and electronic transition during the excitation process and the tendency in absorption and emission wavelengths have been interpreted by frontier molecular orbitals. (C) 2013 Elsevier B.V. All rights reserved.