Comparative study of electronic structure and optical properties of a series of Pt(II) complexes containing different electron‐donating and ‐withdrawing groups: a DFT study

We report a quantum‐chemistry study of electronic structures and spectral properties of a series of Pt(II) complexes containing different substituents (? CH₃ ( 1 ), ? OCH₃ ( 2 ), ? NO₂ ( 3 ), ? CF₃ ( 4 ), and ? COOH ( 5 )). 1 and 2 have been previously synthesized in experiment, while 3 – 5 are artificial complexes that we suggest can be used to investigate the electron‐withdrawing effect on charge injection, transport, absorption, and phosphorescence properties. The results reveal that the stronger electron‐donating and ‐withdrawing groups show stronger absorption intensity, while the phosphorescence efficiency is generally higher for complexes containing electron‐donating substituents. 1 and 2 are easier for hole injection, while 3 – 5 are easier for electron injection. The enhanced electron injection abilities of 3 – 5 will confine more excitons in the light‐emitting layer (EML) and may not result in lower electroluminescence (EL) efficiency than 1 and 2 . These results suggest that the three artificial complexes may be new emitters in organic light‐emitting diodes (OLEDs). Copyright © 2009 John Wiley & Sons, Ltd.