We have developed a new process at high vacuum (5 × 10−5 Torr) and high temperature (300 °C) to produce meridional iridium complexes from the dimer; interestingly, mer-Ir(m-ppy)3 overthrows the concept of poor efficiency and shows excellent efficiency which is almost equal to that of fac-Ir(ppy)3, fac-Ir(m-ppy)3 and (ppy)2Ir(acac).