Electron mobility determination of efficient phosphorescent iridium complexes with tetraphenylimidodiphosphinate ligand via transient electroluminescence method

The electron mobility of Alq(3) and iridium complexes was determined via transient electroluminescence (EL) method based on ITO (indium tin oxide)/di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane/complex/LiF/Al with short and rectangular driving voltage pulses. Apparent values of the electron mobility (mu(e)) in complexes have been investigated from their onset of EL upon different driving voltages. The result reveals that the mu(e), 4.31 x 10(-6) cm(2)/V.s, of the efficient phosphorescent material Ir(tfmppy)(2)(tpip) [1, tfmppy - 4-trifluoromethylphenylpyridine, tpip - tetraphenylimido-diphosphinate] under electric field of 1300 (V/cm)(1/2) is as high as that of Alq(3), which indicates that the good device performances of 1 are partly due to its high electron mobility. (C) 2012 American Institute of Physics. [doi:10.1063/1.3684971]