Organic Radical Emitters for OLED Internal Quantum Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current organic light-emitting diodes (OLEDs) face limitations in achieving high internal quantum efficiency, particularly in converting triplet excitons to singlet excited states for efficient light emission, with existing emitters only approaching 100% efficiency through phosphorescent or thermal-assisted delayed fluorescence (TADF) mechanisms.
Innovation Solution
The development of organic radicals that facilitate reverse intersystem crossing (RISC) when combined with fluorescent emitters, either through chemical or physical blending, or by being conjugated as pendent groups, enabling the conversion of triplet excitons to singlet excited states, thereby maximizing internal quantum efficiency to 100%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent or TADF mechanisms are used to convert triplet excitons to singlet excited states, then internal quantum efficiency approaches 100%, but device complexity and material cost increase
Solution Approach 1:
The patent extracts and utilizes the unique properties of organic radicals (unpaired electron in a doubly degenerate orbital) to enable reverse intersystem crossing from triplet to singlet states. By incorporating radical-containing host materials or dopants, the system achieves efficient triplet exciton utilization without requiring complex phosphorescent iridium complexes or TADF emitter designs, thus simplifying the overall device architecture while maintaining high internal quantum efficiency.
2Use of energy by moving object
If phosphorescent emitters are used to achieve high internal quantum efficiency, then triplet exciton conversion is efficient, but the emission mechanism requires heavy metal complexes increasing material cost
Solution Approach 1:
The patent employs organic radicals as host materials or dopants that can be integrated into conventional OLED structures. These radical-containing compounds offer a cost-effective alternative to expensive phosphorescent iridium complexes while achieving comparable or superior internal quantum efficiency through radical-assisted reverse intersystem crossing mechanisms.
3Device complexity
If conventional fluorescent emitters are used, then device structure is simple, but internal quantum efficiency is limited due to inability to utilize triplet excitons
Solution Approach 1:
The patent changes the electronic structure parameter of the host or dopant material by incorporating organic radicals with unpaired electrons. This parameter change enables the material to facilitate reverse intersystem crossing from triplet to singlet states, allowing efficient utilization of triplet excitons that would otherwise be lost in conventional fluorescent emitters, thereby achieving high internal quantum efficiency while maintaining relatively simple device architecture.
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
This approach allows for the achievement of 100% internal quantum efficiency in OLEDs, surpassing the efficiency of existing emitters by utilizing radical-assisted RISC and doublet emission mechanisms, paving the way for the next generation of highly efficient OLEDs.
Implementation Method 1
The development of organic radicals that facilitate reverse intersystem crossing (RISC) when combined with fluorescent emitters, either through chemical or physical blending, or by being conjugated as pendent groups, enabling the conversion of triplet excitons to singlet excited states
Implementation Method 2
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Data Source
AI summary
Compounds that are organic radicals that can have a dual function. The compounds can be fluorescent emitters that emit in the near-IR. The compounds can also facilitate reverse intersystem crossing (RISC) to convert triplet excitons in an OLED to singlet excited states to maximize utilization of generated excitons in the OLED and approach 100% internal quantum efficiency.