Red Phosphorescent Compound for OLED Color Purity
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Solution Overview
Problem
Current red phosphorescent compounds for organic electroluminescent devices face challenges in achieving high luminescence efficiency, color purity, and long luminescence lifetime, as increased color purity leads to decreased spectral luminous efficacy.
Innovation Solution
A red phosphorescent compound of Formula 1, specifically iridium (III) (2-(3-methylphenyl)-6-methoxyquinolinato-N,C2′)(2,4-pentanedionate-O,O), is used as a dopant in the light-emitting layer, combined with host materials like Al complexes and carbazole derivatives, to enhance luminescence efficiency and color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If red phosphorescent compounds with high color purity are used, then color purity is improved, but spectral luminous efficacy decreases
Solution Approach 1:
The patent applies parameter changes by systematically varying the substituent groups (R1-R6) on the quinoline and phenylpyridine ligands, including different alkyl groups, alkoxy groups, and their positions. This modifies the electronic structure and HOMO-LUMO energy levels of the phosphorescent complex, enabling optimization of both color purity (CIE coordinates) and spectral luminous efficacy simultaneously
Solution Approach 2:
The patent uses composite material strategy by combining the iridium center with specific organic ligands (quinoline derivative, phenylpyridine derivative) and beta-diketonate ligands. This creates a tailored phosphorescent complex where each component contributes specific properties: the iridium provides phosphorescence, the quinoline/phenylpyridine controls color, and the beta-diketonate enhances stability and luminescence efficiency
2Use of energy by moving object
If red phosphorescent compounds with high luminescence efficiency are used, then luminescence efficiency is improved, but luminescence lifetime decreases
Solution Approach 1:
The patent modifies molecular parameters including the choice of beta-diketonate ligands (acac, pic, hfac, thenoyltrifluoroacetone) and their substitution patterns, which directly influence the radiative and non-radiative decay rates. By adjusting these parameters, the patent achieves high luminescence efficiency while maintaining acceptable lifetime for OLED applications
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 red phosphorescent compound achieves high color purity, high luminance, and long lifetime in organic electroluminescent devices, with desired effects realized when used within a specific weight range of 0.5 to 20% as a dopant, improving the overall performance of the devices.
Implementation Method 1
Fluorescent materials using triplet excitons, which are involved in the phosphorescence process, whose probability of formation is 75%, exhibit high luminescence efficiency
Implementation Method 2
When charge carriers are injected into an organic film formed between an electron injecting electrode (cathode) and a hole injecting electrode (anode) of an organic electroluminescent device, electrons combine with holes to create electron-hole pairs, which then decay to emit light
Data Source
AI summary
Disclosed herein is a red phosphorescent compound of the following Formula 1:whereinis includes a phenyl part and a quinoline part, the quinoline part has one substituent selected from a C1-C4 alkoxy group and the phenyl part has substituents independently selected from hydrogen, C1-C4 alkyl groups and C1-C4 alkoxy groups, andis selected from 2,4-pentanedione, 2,2,6,6-tetramethylheptane-3,5-dione, 1,3-propanedione, 1,3-butanedione, 3,5-heptanedione, 1,1,1-trifluoro-2,4-pentanedione, 1,1,1,5,5,5-hexafluoro-2,4-pentanedione, and 2,2-dimethyl-3,5-hexanedione.