Homoleptic iridium(III) carbene complexes as efficient blue OLED phosphors?

Homoleptic Ir(III) carbene complexes were particular suitable in serving as the OLED blue phosphors. These carbene complexes exhibit both the destabilized T1 and MC dd excited states due to the high lying π* orbital of carbene fragments and stronger Ir-C bonding interaction. Hence, tuning emission to true-blue color can be done by stabilization of T1 state via addition of electron deficient substituent(s) at the carbene fragment, resulting in the increased energy gap between the T1 excited state and metal-centered dd quenching state. The enlarged energy gap retarded the non-radiative decay, making them one of the best candidates in showing both the efficient and durable blue phosphorescence. Underlining theory and representative examples will be discussed in this presentation.