Iridium OLED Emitter Compounds for Saturated Color Emission
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Solution Overview
Problem
Existing organic light-emitting diodes (OLEDs) face challenges in achieving saturated colors and efficient light emission, particularly in full color displays, due to limitations in phosphorescent emissive molecules and the need for improved organic materials that can produce high-quality white light.
Innovation Solution
The development of a compound, Ir(L A ) m (L B ) 3-m, with a specific structure and substituents, including imidazole moiety B and varying substituents R A<, R B<, and R C<, which can be used in OLEDs to enhance emission properties and improve color saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional phosphorescent emissive molecules are used in OLEDs, then the device structure is established, but the color saturation and emission efficiency are insufficient
Solution Approach 1:
The patent modifies the molecular structure of phosphorescent emitters by introducing specific ligand configurations and substituent groups (R1, R2, R3, R4, R5, R6) to iridium complexes, changing the photophysical parameters to achieve both high emission efficiency and saturated colors. The structural modifications include varying the cyclometalating ligands and ancillary ligands to optimize the HOMO-LUMO gap and phosphorescence quantum yield.
Solution Approach 2:
The invention employs composite molecular structures combining iridium metal center with organic ligands (cyclometalating ligands and ancillary ligands) to create phosphorescent emissive materials that exhibit both high efficiency and saturated color emission. The composite nature allows synergistic effects between the metal's heavy atom effect and the organic ligands' optical properties.
2Adaptability or versatility
If white light emission is achieved in OLEDs, then full color display capability is enabled, but the color purity of individual pixels is reduced
Solution Approach 1:
The patent divides the white light emission system into separate red, green, and blue phosphorescent emissive layers, each containing specifically designed iridium complexes tuned to emit in the respective color range. This segmentation allows each pixel to emit saturated colors while the combination produces full color display capability, eliminating the need for color filters.
Solution Approach 2:
The invention applies local quality by designing different ligand configurations in different emissive layers to achieve color-specific optimization. Each layer's iridium complex is tailored with specific substituents (R1-R6) to emit in a narrow spectral band, providing high color purity locally while maintaining overall full-color capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The compound enhances the emission efficiency and color purity of OLEDs, enabling better performance in full color displays and white light production, addressing the limitations of conventional materials.
Implementation Method 1
One application for phosphorescent emissive molecules is a full color display
Implementation Method 2
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Data Source
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AI summary
A compound, Ir(LA)m(LB)3-m, having a structure of Formula I, , is provided. In Formula I, each of moiety A and moiety C is independently a 5- or 6-membered ring or a polycyclic fused ring system comprising 5- or 6-membered rings; moiety B is a 5-membered heterocyclic ring; Z1, Z2, and Z3 are C or N; m is 1 or 2; at least one of R1, R2, R3, R4 has a structure of Formula II, or is a 5-membered heterocyclic ring; each of X1, X2, X3, X4, and X5 is CR or N; each of R1, R2, R3, R4, RA, RB, RC, and R is hydrogen or a General Substituent; at least one of R1a, R2a, R3a, R4a, R5a is cycloalkyl, alkyl, silyl, germyl, deuterated variants thereof, fluorinated variants thereof, and combinations thereof. Formulations, OLEDs, and consumer products containing the compound are also provided.