Iridium Organometallic Dopant for OLED Emission Efficiency

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Solution Overview

Problem

Current organic light-emitting devices (OLEDs) face limitations in achieving optimal emission efficiency and external quantum efficiency due to challenges in finding suitable dopants for the emission layer that balance hyper-conjugation and metal-to-ligand charge transfer, leading to suboptimal out-coupling and emission efficiency.

Innovation Solution

The development of an organometallic compound represented by Formula 1, which includes specific iridium-based structures and groups like —Ge(Q3)(Q4)(Q5), is used as a dopant in the emission layer, enhancing hyper-conjugation and increasing the amount of metal-to-ligand charge transfer, thereby improving emission efficiency and external quantum efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional dopants are used in the emission layer, then device structure is simple, but emission efficiency and external quantum efficiency are suboptimal

Engineering Contradiction:

Improveemission efficiencyVSAvoidcompound structure complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent modifies the chemical parameters of the dopant compound by incorporating specific structural features: a C5-C30 carbocyclic group or C1-C30 heterocyclic group, and at least one —Ge(Q3)(Q4)(Q5) group where Q3-Q5 are hydrogen, deuterium, or halogen atoms. These parameter changes in the molecular structure optimize hyper-conjugation and metal-to-ligand charge transfer, thereby improving emission efficiency and external quantum efficiency while maintaining reasonable structural complexity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite organometallic compound that combines multiple functional groups (carbocyclic/heterocyclic rings, germanium-containing groups, and iridium center) into a single dopant molecule. This composite structure synergistically enhances both hyper-conjugation effects and metal-to-ligand charge transfer, resolving the contradiction between structural simplicity and emission performance by integrating multiple functional elements into one optimized compound

Inventive Principle:

Principle #40Composite materials

2Productivity

If dopants with strong hyper-conjugation are used, then emission efficiency improves, but out-coupling becomes suboptimal

Engineering Contradiction:

Improveemission efficiencyVSAvoidout-coupling

Core Design Contradiction:

ProductivityVSIllumination intensity

Solution Approach 1:

The patent carefully balances the hyper-conjugation parameter by selecting specific carbocyclic or heterocyclic groups (C5-C30 or C1-C30) combined with —Ge(Q3)(Q4)(Q5) groups. This parameter optimization ensures sufficient hyper-conjugation for high emission efficiency while maintaining appropriate out-coupling properties, resolving the trade-off between these two competing requirements

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional organometallic compounds are used, then manufacturing is straightforward, but external quantum efficiency is limited

Engineering Contradiction:

Improveexternal quantum efficiencyVSAvoidsynthesis complexity

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent optimizes the synthesis parameters by designing a dopant compound with a specific iridium-based core and well-defined ligand groups (C5-C30 carbocyclic or C1-C30 heterocyclic with —Ge(Q3)(Q4)(Q5)). These parameter choices facilitate conventional organometallic synthesis methods while achieving superior external quantum efficiency, balancing manufacturability with performance improvement

Inventive Principle:

Principle #35Parameter changes

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 organometallic compound increases the emission efficiency of OLEDs by enhancing the out-coupling of light, leading to improved external quantum efficiency and reduced non-emission transitions, resulting in better performance and lifespan characteristics.

Implementation Method 1

increasing the amount of metal-to-ligand charge transfer, thereby improving emission efficiency and external quantum efficiency

Methodology Applied

Scientific EffectMetal-to-ligand charge transfer:

Implementation Method 2

enhancing hyper-conjugation and increasing the amount of metal-to-ligand charge transfer

Methodology Applied

Scientific EffectHyper-conjugation:

Implementation Method 3

increases the emission efficiency of OLEDs by enhancing the out-coupling of light

Methodology Applied

Scientific EffectLight out-coupling:

Implementation Method 4

reduced non-emission transitions, resulting in better performance and lifespan characteristics

Methodology Applied

Scientific EffectNon-emission transitions:

Data Source

PatentUS20230157152A1Organometallic compound, light-emitting device including the same, and electronic apparatus including the light-emitting device

Publication Date: 2023.05.18 SAMSUNG DISPLAY CO LTD

AI summary

An organometallic compound represented by Formula 1:wherein Y1 to Y4 are each independently C or N, one of Y1 to Y4 is N bonded to iridium in Formula 1, and another of Y1 to Y4 is C bonded to ring CY2 in Formula 1, Y9 is O, S, N(R19), C(R19a)(R19b), or Si(R19a)(R19b), X2 is C, ring CY1 and ring CY2 are each independently a C5-C30 carbocyclic group or a C1-C30 heterocyclic group, a1 and a2 are each independently an integer from 0 to 20, and R1, R19, R19a, R19b, R2, R30a, R30b, and R37 are each as described herein.