Purinylidene‐Based Iridium(III) Phosphors for Efficient Purple Phosphorescence and Organic Light‐Emitting Devices

It is very challenging to achieve highly efficient and low roll‐off purple to deep‐blue organic light‐emitting diodes (OLEDs) due to the limited selection of suitable emitters. Herein, a series of Ir(III) phosphors‐bearing purinylidene‐based N‐heterocyclic carbene (NHC) chelates are reported, namely, f ‐ct2a–d, which have successfully turned the emission peak maxima to the purple region (427–432 nm) in degassed toluene, together with high quantum yields of 77%–81%. Notably, f ‐ct2b is further employed as the phosphorescent dopant in the fabrication of OLEDs to afford deep‐blue emission paking at 448 nm and an EQE of 6.7% at 100 cd m −2 . Furthermore, a true‐blue hyperphosphorescent OLED with 21 wt% of f ‐ct2a as sensitizer and 1 wt% of ν‐DABNA as terminal emitter is also fabricated, giving excellent performance with max. EQE up to 22.2% and an EQE of 19.2% at a brightness of 100 cd m −2 .