Since the phosphorescence organic lightemitting diodes (PHOLEDs) were discovered by Stephen R. Forrest in 1998, [1] high performance of green and red emitting PHOLEDs have been successfully fabricated using vacuum-and solution-processed techniques. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Recently, the device performances of deep-blue PHOLEDs have been improved dramatically in terms of external quantum efficiency (EQE) and meeting the 1931 Commission Internationale de L'Eclairage CIE(x, y) color coordinate requirements. [20][21][22] Highly efficient deep-blue PHOLEDs are usually produced by vacuum deposition because this technique makes it possible to stack multilayer devices to match charge carrier balance in the emission layer (EML). [23][24][25][26][27][28][29][30] In contrast, solution-processed deep-blue PHOLEDs with high EQEs still do not meet the standard blue CIE(x, y) color coordinate requirements of the National Television System Committee or the European Broadcasting Union (EBU). The reason why solution-processed deep-blue PHOLEDs have low efficiencies is that it is difficult to deposit hole transport layers (HTLs) because the bottom layer is damaged by solvents. In particular, in deepblue PHOLEDs, a mismatch of energy levels between host and dopant materials is induced by the wide bandgap (E g ) of high triplet energy (E T ) host materials, which suppresses back energy transfer via dopant to the host and makes it difficult to balance hole and electron densities in the EML. This issue must be overcome to achieve high performance deep-blue PHOLEDs.Solution-processed PHOLEDs have attractive advantages such as low cost fabrication, less power consumption, large areas, and flexible production. In particular, deep-blue solution-processed PHOLEDs are highly sought after by OLED industries for large-scale commercialization. Several reports have been issued on solution-processed blue PHOLEDs with EQE values ≥ 20% and CIE y coordinates of ≤ 0.3. Bis(4,6difluorophenylpyridnato)iridium (picolinate) (Flrpic) and its derivatives are among the most extensively studied blue Ir(III) Solution-processed phosphorescence organic light-emitting diodes (PHOLEDs) are an increasingly attractive option as compared with vacuumprocessed PHOLEDs due to their lower costs, large areas, and flexible production. Currently, the majority of reported solution-processed PHOLEDs are produced using red and green triplet emitters. The earlier reports on blue solution-processed PHOLEDs describe poor Commission International de l'Éclairage color coordinates (CIE(x, y)) and low external quantum efficiencies (EQEs). It is difficult to produce efficient solution-processed deep-blue PHOLEDs that meet high EQE and CIE y color coordinate ≤ 0.15 requirements. The authors design and synthesize three new carbenic homoleptic deep-blue emitting Ir(III) complexes for solution-processed PHOLEDs. The introduction of bulky tert-butyl and trifluoromethyl (CF 3 ) substituents at a suitable position on the benzylated pyridoimidazole mo...

Highly efficient (D–π–A)-type host and green Ir(iii) complexes are introduced for solution-processed PHOLEDs that achieve high CE with considerably high EQE. The devices with symmetrical complex show more stable than those with asymmetrical complex.

Highly efficient green-emitting phosphorescent Ir(iii) complexes with meridional configurations are introduced for solution-processed PHOLEDs that achieve high CE with high EQE. The unexpected high PLQYs leads to high luminous efficiency.

In the present study, three new highly efficient green emitting heteroleptic Ir(III) complexes based on 5H-benzo[c][1,5]naphthyridin-6-one derivatives were designed and synthesized for the solution-processed PHOLEDs. The Ir(III) complex, Ir1 consists...