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Two new cationic iridium complexes bearing cyclometalated carbene ligands have been prepared, and the photophysical and electrochemical properties have been investigated. In degassed acetonitrile solutions, these complexes exhibit yellow light emission with peaks at 591 and 579 nm, respectively. Both photophysical properties and quantum chemical calculations indicate that photoluminescence of these complexes are mainly from triplet charge-transfer excited states. Solution-processed organic light-emitting diodes based on these complexes exhibit yellow electroluminescences with the maximum current efficiencies of 17.42 and 6.36 cd A −1 and Commission Internationale d’Énclairage(x, y) coordinates (CIE x,y ) of (0.47, 0.51) and (0.51, 0.47), respectively. [ABSTRACT FROM AUTHOR]

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 3 π → 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. [ABSTRACT FROM AUTHOR]

Three new yellow-emitting cationic iridium complexes have been prepared, and the photophysical and electrochemical properties have been investigated. These cationic iridium complexes have excellent thermal stability and can be thermally vacuum-sublimed as phosphorescent dyes for the fabrication of efficient organic light-emitting diodes. The devices based on these complexes give yellow-green electroluminescences with Commission Internationale de L'Eclairage coordinates of (0.38, 0.58), (0.37, 0.58), (0.38, 0.58). The maximum current efficiencies of devices based on these complexes are 20.2, 23.7 and 21.5 cd A −1 that corresponds to maximum external quantum efficiencies of 6.3%, 6.8% and 6.5%, respectively. [ABSTRACT FROM AUTHOR]