Bis-Tridentate Ir(III) Metal Phosphors for Efficient Deep-Blue Organic Light-Emitting Diodes.

Emissive Ir(III) metal complexes possessing two tridentate chelates (bis-tridentate) are known to be more robust compared to those with three bidentate chelates (tris-bidentate). Here, the deep-blue-emitting, bis-tridentate Ir(III) metal phosphors bearing both the dicarbene pincer ancillary such as 2,6-diimidazolylidene benzene and the 6-pyrazolyl-2-phenoxylpyridine chromophoric chelate are synthesized. A deep-blue organic light-emitting diode from one phosphor exhibits Commission Internationale de l'Eclairage (CIE(x,y) ) coordinates of (0.15, 0.17) with maximum external quantum efficiency (max. EQE) of 20.7% and EQE = 14.6% at the practical brightness of 100 cd m-2 .

Room temperature blue phosphorescence: a combined experimental and theoretical study on the bis-tridentate Ir(iii) metal complexes.

A series of new bis-tridentate Ir(iii) complexes (1/1b, 2/2b and 3/3b) incorporating both bis(imidazolylidene)benzene and dianionic functional pyrazolyl (or phenyl) pyridine chelates have been synthesized, among which complexes 2 and 2b exhibit intense and structural sky-blue emission in both solution and solid states. In stark contrast, 1/1b is non-emissive in solution, while 3/3b reveals highly red-shifted emission with a featureless spectral profile. This variation in photophysics is associated with the interchange of metal-chelate bonding in the selected tridentate chelate, which affects both the crystal field stabilization energy and the ππ* transition character of the resulting Ir(iii) metal complexes. In 1/1b, the stabilized metal-centered (MC) dd excited states induce a dominant radiationless channel that accounts for the lack of emission in solution. The appreciable ligand-to-ligand charge transfer (LLCT) in 3/3b rationalizes its broad and featureless emission, which is different from the dominant intraligand ππ* transition in 2/2b. The combination of experimental and theoretical approaches thus provides fundamental insight into the influence of chelates as well as the metal-chelate interaction, which is beneficial for the future design of efficient and robust Ir(iii) phosphors for OLED applications.

Bis-Tridentate Ir(III) Complexes with Nearly Unitary RGB Phosphorescence and Organic Light-Emitting Diodes with External Quantum Efficiency Exceeding 31%.

A new class of neutral bis-tridentate Ir(III) metal complexes that show nearly unitary red, green, and blue emissions in solution is prepared and employed for the fabrication of both monochrome and white-emitting organic light-emitting diodes, among which a green device gives external quantum efficiency exceeding 31%.