Abstract
A series of Pt(II) complexes were successfully synthesized using the imidazolium - pyridinium carbene ligands. Complexes 5 - 7 which have intramolecular hydrogen bonding achieved high quantum efficiency (78 ~ 99%). The luminescence and color switch are most likely relevant to the variations in intermolecular interactions in packing of Pt(II) moieties, which are significantly perturbed by fine powder and crystalline solid. The devices fabricated by complex 5 showed green EL emission with λmax = 560 nm which was corresponding to the (0.43, 0.54) CIE coordinates, and an external quantum efficiency of up to 11.8%.