OLED Triplet-Accepting Material Delayed Fluorescence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light-emitting diodes (OLEDs) face efficiency issues due to high non-radiative decay of triplet excitons, leading to reduced device lifetime and quantum efficiency, as up to 75% of excitons undergo non-radiative decay instead of radiative emission.
Innovation Solution
Incorporating a triplet-accepting material with a lower excited triplet state energy level than the light-emitting material to facilitate triplet-triplet annihilation, allowing for radiative decay and delayed fluorescence, thereby enhancing device efficiency and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If triplet excitons are allowed to decay naturally in fluorescent OLEDs, then the device structure is simple, but quantum efficiency is limited to 25% due to non-radiative decay of triplet excitons
Solution Approach 1:
The patent introduces a triplet-quenching material as an intermediary substance in the light-emitting layer. This material has a lower triplet energy level than the electroluminescent material, enabling it to accept triplet excitons through energy transfer and quench them non-radiatively, thereby protecting the electroluminescent material from triplet-triplet or triplet-singlet interactions that reduce device lifetime.
Solution Approach 2:
The patent converts the harmful effect of triplet excitons (which cause non-radiative decay and reduce device lifetime) into a beneficial effect by using the triplet-quenching material to selectively quench triplet excitons while preserving singlet excitons. This approach transforms the problematic triplet state into a protective mechanism that extends device lifetime without significantly compromising quantum efficiency.
2Duration of action of stationary object
If triplet-quenching material is added to prevent triplet-triplet interactions, then device lifetime is extended, but energy is lost in non-light emitting pathways
Solution Approach 1:
The triplet-quenching material acts as a mediator that selectively interacts with triplet excitons through energy transfer. By having a lower triplet energy level than the electroluminescent material, it accepts triplet excitons and provides a safe decay pathway that prevents harmful triplet-triplet or triplet-singlet interactions, thereby extending device lifetime while minimizing energy loss.
3Duration of action of stationary object
If perylene derivative is blended with light-emissive material to improve lifetime, then device lifetime increases, but emission spectrum undergoes significant red-shift
Solution Approach 1:
The patent applies local quality by introducing a specifically designed triplet-quenching material with appropriate energy levels that selectively interacts with triplet excitons without significantly affecting the singlet exciton emission. This localized intervention at the triplet state level allows lifetime extension while preserving the original emission spectrum characteristics of the electroluminescent material.
Solution Approach 2:
The patent changes the energy level parameter of the triplet-quenching material to be lower than the electroluminescent material's triplet energy level. This parameter selection enables effective triplet quenching while minimizing impact on the emission spectrum, avoiding the significant red-shift observed with perylene derivatives.
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 triplet-accepting materials in OLEDs increases the probability of triplet-triplet annihilation, leading to improved radiative decay pathways, extended device lifetime, and enhanced efficiency by converting non-radiative decays into delayed fluorescence.
Implementation Method 1
Incorporating a triplet-accepting material with a lower excited triplet state energy level than the light-emitting material to facilitate triplet-triplet annihilation
Implementation Method 2
facilitate triplet-triplet annihilation, allowing for radiative decay and delayed fluorescence
Implementation Method 3
allowing for radiative decay and delayed fluorescence, thereby enhancing device efficiency and lifetime
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Composition for use in an organic light-emitting device, the composition having a fluorescent light-emitting material and a triplet-accepting material subject to the following energetic scheme: 2 X T1A > S1A > S1E, or T1A + T1E > S1A > S1E in which: T1A represents a triplet excited state energy level of the triplet-accepting material; TIE represents a triplet excited state energy level of the light-emitting material; S1A represents a singlet excited state energy level of the triplet-accepting material; and S1E represents a singlet excited state energy level of the light-emitting material; and in which light emitted by the composition upon excitation includes delayed fluorescence.