OLED Phosphorescent Emitter for Saturated Color
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Solution Overview
Problem
Existing organic light emitting diodes (OLEDs) face challenges in achieving high efficiency and color purity for full color displays, particularly in producing saturated red, green, and blue pixels.
Innovation Solution
A compound of Formula MLALB is introduced, where M is Pd or Pt, LA comprises Formula I, and LB comprises Formula II, with specific structural features that enable efficient energy transfer and emission in OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used in OLEDs, then device fabrication is simpler and costs are lower, but efficiency and color purity are insufficient for full color displays
Solution Approach 1:
The patent modifies the chemical structure parameters of organic emissive materials by incorporating specific heterocyclic rings (triazole, tetrazole, oxadiazole, thiadiazole) and adjusting substituent groups to optimize HOMO-LUMO energy gaps. This enables precise control over emission wavelength and color saturation while maintaining phosphorescent efficiency for full color display applications
Solution Approach 2:
The patent employs composite phosphorescent emitter formulations combining heavy metal complexes (Ir, Pt, Os) with organic ligands containing electron-donating and electron-withdrawing groups. These composite materials achieve both high quantum efficiency and narrow emission bandwidths required for saturated red, green, and blue pixels
2Reliability
If white OLED with absorption filters is used, then device structure is simpler, but emission efficiency and color saturation are reduced
Solution Approach 1:
The patent divides the single white emission into three separate phosphorescent emissive layers, each optimized for a specific color (red, green, blue). Each layer uses tailored ligand structures with specific heterocyclic moieties to achieve narrow emission bandwidths and high color saturation without requiring absorption filters, thereby eliminating energy loss
Solution Approach 2:
The patent introduces heavy metal complexes (Ir, Pt, Os) as intermediary phosphorescent emitters that enable direct emission of saturated colors through phosphorescence. These intermediaries convert electrical energy directly into narrow-band phosphorescent emission, bypassing the need for broad-spectrum white emission and subsequent optical filtering
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 in OLEDs enhances the efficiency and color purity of the emitted light, leading to improved performance in full color displays with saturated colors.
Implementation Method 1
One application for phosphorescent emissive molecules is a full color display
Implementation Method 2
Z1 is a carbene carbon and moiety A is joined to M by a metal-carbene bond
Data Source
AI summary
A compound of Formula MLALB where M is Pd or Pt; LA comprises Formula I,and LB comprises Formula II,is provided. In Formulas I and II, moiety A is a monocyclic ring or a polycyclic fused ring system; Z1 is a carbene carbon; each of X1 to X12 and Z2 to Z4 is C or N; each of Y1 and Y2 is a linking group; each of K3 and K4 is a direct bond or a linking group; LA and LB are joined by a direct bond or a linking group; each R, R′, Rα, Rβ, RA, RB, RC, RD, and RE is hydrogen or a General Substituent defined herein; and LA and LB can be further linked to form a macrocyclic tetradentate ligand. Formulations, OLEDs, and consumer products containing the compound are also provided.