Delayed Fluorescence Compound for OLED Efficiency
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Solution Overview
Problem
Current OLEDs using fluorescent compounds have limited emitting efficiency due to the exclusion of triplet excitons from emission, with no blue phosphorescent compound meeting efficiency and reliability requirements.
Innovation Solution
Development of a delayed fluorescence compound with a specific molecular structure, incorporating an acridine electron donor moiety and an electron acceptor moiety linked by a linker, which allows both singlet and triplet excitons to participate in emission, enhancing quantum efficiency and reducing red shift issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fluorescent compounds are used in OLED emitting layers, then the device structure and operation are simplified, but the emitting efficiency is limited to maximum 25% due to exclusion of triplet excitons
Solution Approach 1:
The patent introduces a delayed fluorescence compound as an intermediary material in the emitting layer that mediates between singlet and triplet excitons. This compound accepts energy from both singlet and triplet excitons and re-emits as singlet excitons, effectively converting non-emissive triplet excitons into emissive states without requiring complex phosphorescent materials or heavy metal atoms.
Solution Approach 2:
The patent changes the photophysical parameters of the emitting layer by using delayed fluorescence compounds with specific properties: long-lived excited states (microsecond to millisecond range), appropriate energy levels, and high radiative quantum efficiency. This parameter change enables the system to utilize both singlet and triplet excitons while maintaining simplified device structure.
2Productivity
If phosphorescent compounds are used to utilize both singlet and triplet excitons, then emitting efficiency improves, but blue phosphorescent compounds lack reliability and stability
Solution Approach 1:
The patent converts the typically harmful non-radiative decay of triplet excitons into a beneficial process by using delayed fluorescence compounds that can accept energy from triplet excitons and re-emit radiatively. This approach avoids the stability issues of phosphorescent materials while still utilizing triplet excitons for light emission.
Solution Approach 2:
The patent employs organic delayed fluorescence compounds with short-lived excited states compared to phosphorescent materials, avoiding the need for expensive and unstable blue phosphorescent compounds. These compounds provide sufficient emission efficiency without requiring heavy metal atoms or complex molecular structures.
3Device complexity
If conventional fluorescent compounds are used, then the emitting layer structure remains simple, but red shift occurs and limits color purity
Solution Approach 1:
The patent applies local quality by designing delayed fluorescence compounds with specific molecular structures and energy level configurations at localized positions within the emitting layer. The compounds are positioned to interact with both host and dopant materials, creating localized energy transfer zones that minimize red shift while maintaining overall structural simplicity.
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 delayed fluorescence compound achieves a theoretical quantum efficiency of 100% by engaging both singlet and triplet excitons in emission, significantly improving OLED efficiency and minimizing red shift, thereby enhancing the emitting efficiency of OLEDs.
Implementation Method 1
delayed fluorescence compound having excellent emitting efficiency
Implementation Method 2
the electron and the hole are combined and become extinct such that the light is emitted from the OLED
Data Source
AI summary
Embodiments relate to a delayed fluorescence compound ofThe excitons in the triplet state are engaged in emission such that the emitting efficiency of the delayed fluorescent compound is increased. Embodiments also relate to a display device with an organic light emitting diode (OLED) that includes the delayed fluorescence compound.