Lanthanide imidodiphosphinate complexes: Synthesis, structure and new aspects of electroluminescent properties

The lanthanide imidodiphosphinate complexes Ln(pip)3 (Ln = Ce, Nd, Tb, Ho) were prepared from the corresponding Ln[N(SiMe3)2]3 with [Ph2P(O)]2NH in a quantitative yield. X-ray single structure analysis of Ce(pip)3 has revealed that the lanthanide ion in these compounds coordinated by three bidentate [Ph2P(O)NP(O)Ph2]− ligands and THF molecule. With respect to the organic light emitting diodes (OLED) application, the simple electroluminescent (EL) devices with a multilayer configuration ITO/TPD/Ln(pip)3/Yb, ITO/CBP/Ln(pip)3/Yb, ITO/TPD/Ln(pip)3/Alq3/Yb, ITO/TPD/Alq3/Ln(pip)3/Yb were fabricated. It was found that the lanthanide imidodiphosphinate complexes possess the hole-blocking and electron-transporting ability and it was also observed the exciplex emission between these complexes and TPD.