Deep Blue Phosphorescent Organic Light‐Emitting Diodes with CIEy Value of 0.11 and External Quantum Efficiency up to 22.5%

Abstract

Organic light-emitting diodes (OLEDs) based on red and green phosphorescent iridium complexes are successfully commercialized in displays and solid-state lighting. However, blue ones still remain a challenge on account of their relatively dissatisfactory Commission International de L'Eclairage (CIE) coordinates and low efficiency. After analyzing the reported blue iridium complexes in the literature, a new deep-blue-emitting iridium complex with improved photoluminescence quantum yield is designed and synthesized. By rational screening host materials showing high triplet energy level in neat film as well as the OLED architecture to balance electron and hole recombination, highly efficient deep-blue-emission OLEDs with a CIE at (0.15, 0.11) and maximum external quantum efficiency (EQE) up to 22.5% are demonstrated. Based on the transition dipole moment vector measurement with a variable-angle spectroscopic ellipsometry method, the ultrahigh EQE is assigned to a preferred horizontal dipole orientation of the iridium complex in doped film, which is beneficial for light extraction from the OLEDs.

Review on the Electroluminescence Study of Lanthanide Complexes

“…Moreover, traditional fluorescence materials could only utilize singlet excitons to radiate photo‐ns, which limit the maximum internal quantum efficiency (IQE) of 25%. The phosphorescence materials and thermally activated delayed fluorescence (TADF) materials could employ both singlet and triplet excitons to achieve theoretical maximum IQE up to 100%.…”

External Quantum Efficiency Exceeding 24% with CIEy Value of 0.08 using a Novel Carbene‐Based Iridium Complex in Deep‐Blue Phosphorescent Organic Light‐Emitting Diodes

“…(Figure 1). [9][10][11][12][13][14][15][16] The Ir(III) complex, mer-tris(N-phenyl, N-benzyl-pyridoimidazol-2-yl)iridium(III) (mer-Ir1), was prepared by reacting the NHC ligand in the presence of silver carbonate, IrCl 3 •3H 2 O and sodium carbonate in degassed 2-ethoxyethanol solution under reflux, as shown in Figure 2a. The mixture of the facial (fac) and meridonial (mer) isomer was obtained and separated by repeated column chromatography.…”

Introducing a Nonvolatile N‐Type Dopant Drastically Improves Electron Transport in Polymer and Small‐Molecule Organic Transistors

“…Over the past few decades, organic semiconductors (OSCs) have become the material of choice for a wide range of emerging optoelectronic applications, a few examples of which include organic light‐emitting diodes (OLEDs), organic photovoltaics (OPVs) and organic thin‐film transistors (OTFTs) . During this time, increased effort has been directed toward tuning OSCs' properties, including their processing characteristics and charge carrier transport primarily via the development of new materials and their application in devices with improved operating characteristics .…”