We have developed a new process at high vacuum (5 x 10(-5) Torr) and high temperature (300 degreesC) 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)(2)Ir(acac).