Electrophosphorescence Generated from Ir(III) Carbene Phosphors and Respective Hyperluminescence

Organic light-emitting diode (OLED) is considered as one most promising technology to facilitate visual communication in the form of monitors and wearable and head-mounted display devices. Therefore, much efforts have been devoted in improving their performances and, as the result, better and more reliable materials, particularly the emitters, have been developed in both academic and industrial sectors. Among the emissive materials, Ir(III) metal complexes have been recognized for their remarkable stability and efficient green and red luminescence and, nowadays, they have been employed as an integral component of commercially viable OLED devices. However, much less progresses have been made on the respective blue emitters. This shortfall prompted more research on both the blue emissive transition-metal based phosphors for future advancement of OLED technology.<br/>In general, the Ir(III) metal atom is capable to promote the facile intersystem crossing facilitated by spin-orbit coupling, allowing full utilization of both the electro-generated singlet and triplet excitons. There are two possible class of Ir(III) complexes suitable for making the demanded blue phosphors. One involves functional cyclometalating chelates linked to N-donor fragment such as pyridine, pyrazole or imidazole, in the form of either the homoleptic or heteroleptic derivatives Ir(C^N)₃ and Ir(C^N)₂(L^X), C^N = N-containing aromatics and L^X = anionic ancillary. The alternative designs contain the Ir(III) complexes with N-aryl carbene cyclometalates which can be represented by the generalized formula <i>m</i>-Ir(C^C)₃ and <i>f</i>-Ir(C^C)₃, where <i>m</i>- and <i>f</i>-indicated the meridional and facial coordination arrangements, respectively.<br/>Recently, we reported the successful preparation of several class of homoleptic Ir(III) carbene complexes and employed the same for fabrication of blue OLED devices. Their emission peak max. occurred in the region between 420 to 500 nm in solution state at RT. We believed that they are capable to display the genuine true-blue emission hue and to serve as the chosen blue emitter and sensitizer (or donor) in fabrication of phosphorescent and hyperluminescent OLED devices. Now, this task has been partially accomplished, to which the corresponding syntheses and applications will be discussed in this presentation.