Red and Near Infrared Emissive Bis-Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

Efficient saturated red and near-infrared (NIR) emissive materials are needed in the development of organic light-emitting diodes (OLEDs), with applications extending beyond flat panel displays and lighting luminaries. Toward this aim, a series of bis-tridentate Ir(III) complexes (3a - 3c and 4a - 4c) are designed and synthesized, showing emission spanning the region of 601-694 nm in degassed toluene. Their emission tuning is mainly achieved using monoanionic chromophoric chelates, L1H for red and L2H for deep-red and NIR, where the extended & pi;-conjugation and electron deficient N atoms are introduced synergistically. Moreover, three ancillary chelates, X1H2, X2H2, and X3H2, delivered a secondary influence via varied donor strength to the central Ir(III) atom. The resulting red and deep-red OLED devices exhibit maximum (max.) external quantum efficiencies (EQEs) of 21.4% and 18.1% with peak maximum at 620 and 666 nm, respectively. More impressively, the device based on 4b delivers a NIR emission peak maximum at 702 nm with a maximum EQE of 10.0%. Saturated-red and near-infrared emissive bis-tridentate Ir(III) complexes are synthesized. The representative organic light-emitting diode (OLED) devices exhibit maximum external quantum efficiencies of 21.4% and 10.0% with peak maximums at 620 and 702 nm, confirming their suitability in making phosphorescent OLED devices.image