OLED Emitter Ligand LA for Full Color Display Stability
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Solution Overview
Problem
Current organic light emitting diodes (OLEDs) face challenges in achieving high efficiency and stability for full color displays, particularly in producing saturated red, green, and blue pixels.
Innovation Solution
A compound comprising a first ligand LA of Formula I is used in the organic layer of OLEDs. This ligand is coordinated to a metal M and can join with other ligands to form tridentate, tetradentate, pentadentate, or hexadentate ligands, enhancing the photoluminescent and thermal properties of the OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic materials are used in OLEDs, then cost advantages and flexibility are achieved, but performance and stability are insufficient for full color displays
Solution Approach 1:
The patent employs composite organic materials comprising specific ligand structures coordinated to metal centers (Ir, Pt, Os, Rh) to create OLED emitters that combine the cost-effectiveness and flexibility of organic materials with the high performance and stability of metal coordination compounds. This composite approach enables full color display applications while maintaining manufacturing advantages.
Solution Approach 2:
The patent systematically varies molecular parameters including ligand substitution patterns (RA, RB, RC), ring structures (moiety A and B), and metal centers to optimize the balance between performance, stability, and manufacturing cost. By tuning these parameters, the invention achieves high photoluminescent quantum yield and electroluminescent quantum efficiency while maintaining cost-effectiveness.
2Productivity
If white OLED with absorption filters is used, then full color display is achieved, but efficiency and saturation are reduced
Solution Approach 1:
The patent divides the single white OLED into multiple emissive layers, each containing compounds with specific ligand structures coordinated to different metal centers. Each emissive layer is optimized to emit a particular color (red, green, or blue) with high saturation and efficiency, eliminating the need for absorption filters and achieving both high productivity and color saturation.
Solution Approach 2:
The patent applies different ligand structures and metal coordination compounds to different regions (emissive layers) of the OLED device. Each emissive layer is locally optimized with specific molecular compositions to achieve saturated red, green, or blue emission, thereby improving overall efficiency and color saturation without requiring white light and filters.
3Productivity
If photoluminescent quantum yield is improved, then electroluminescent quantum efficiency increases, but material complexity increases
Solution Approach 1:
The patent develops a universal ligand structure (Formula I) that can be coordinated to multiple metal centers (Ir, Pt, Os, Rh) to produce compounds with high photoluminescent quantum yield and electroluminescent quantum efficiency across different emissive layers. This universal approach simplifies material synthesis and device fabrication while achieving high productivity, as the same ligand framework can be used with different metals to tune emission properties.
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 use of the compound with the ligand LA in OLEDs improves photoluminescent quantum yield, electroluminescent quantum efficiency, and thermal stability, leading to more efficient and reliable full color displays.
Implementation Method 1
improves photoluminescent quantum yield, electroluminescent quantum efficiency
Implementation Method 2
improves photoluminescent quantum yield, electroluminescent quantum efficiency
Implementation Method 3
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Data Source
AI summary
A compound including a first ligand LA ofis provided. In Formula I, each of moiety A and moiety B is a monocyclic ring or a polycyclic fused ring system; each of Z1 to Z4 is C or N; each of K1 and K2 is a direct bond or a linker; L is a direct bond or a linker; at least one RA or RB includes the structure,where G is C, Si, or Ge; each substituents is hydrogen or a General Substituent; and LA is coordinated to a metal M by the dashed lines. Formulations, OLEDs, and consumer products containing the compound are also provided.