Synthesis, characterization, photo- and electro-luminescent properties of blue cationic iridium complexes with nonconjugated bis(pyrazole-1-yl)methane as the ancillary ligand

Two new cationic iridium complexes with nonconjugated bis(pyrazole-1-yl)methane as the ancillary ligand have been prepared, and crystal structure, photophysical and electrochemical properties have been investigated. In degassed acetonitrile solutions, these complexes exhibit blue light emission with peaks at 456 and 453 nm, respectively. Both photophysical properties and quantum chemical calculations indicate that photoluminescence of these complexes are mainly from ligand-centered 3π → π*. Solution-processed organic light-emitting diodes based on these complexes exibit blue light emission with the maximum current efficiencies of 7.34 and 5.36 cd A−1, and maximum external quantum efficiencies of 4.06 and 2.66%, respectively.