OLED Emission Layer Using Delayed Fluorescent Material
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Solution Overview
Problem
Conventional organic light emitting diodes (OLEDs) face limitations in emitting efficiency and color purity due to the involvement of only singlet excitons in the emission process, which restricts their performance in flat panel display devices.
Innovation Solution
Incorporating a combination of a fluorescent material and a delayed fluorescent material with an indolocarbazole moiety and a triazine moiety linked via a phenylene linker in a single emitting material layer, where the delayed fluorescent material's triplet exciton is converted to a singlet exciton, enhancing both emitting efficiency and color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If only singlet excitons are used in the emission process, then the device structure is simple, but the emitting efficiency is limited
Solution Approach 1:
The patent converts the previously harmful or wasted triplet excitons into useful light-emitting species through the delayed fluorescent material. The triplet excitons that would normally be lost are transformed into singlet excitons via reverse intersystem crossing, which then transfer energy to the fluorescent material for light emission. This transforms the harmful energy loss into a beneficial emission mechanism.
Solution Approach 2:
The patent employs a composite emission layer containing both fluorescent material and delayed fluorescent material. The delayed fluorescent material acts as an energy donor that converts triplet excitons to singlet excitons, while the fluorescent material acts as the emitter. This composite system combines the advantages of both materials to achieve high emitting efficiency while maintaining structural simplicity.
2Device complexity
If conventional fluorescent materials are used, then the device structure remains simple, but the color purity is insufficient
Solution Approach 1:
The patent creates a composite emitting material layer combining fluorescent and delayed fluorescent materials. This composite structure enables precise control over emission characteristics, achieving narrow emission bandwidth and high color purity while keeping the overall device structure simple and suitable for manufacturing.
Solution Approach 2:
The patent optimizes parameters such as the energy levels, molecular structures, and ratios of the fluorescent and delayed fluorescent materials to achieve desired emission properties. By carefully adjusting these parameters, the emission bandwidth is narrowed and color purity is enhanced without complicating the device architecture.
3Device complexity
If triplet excitons are not utilized, then the emission mechanism is simple, but the energy utilization is low
Solution Approach 1:
The patent transforms the previously wasted triplet excitons into useful light-emitting energy carriers. The delayed fluorescent material facilitates reverse intersystem crossing of triplet excitons to singlet excitons, which then transfer energy to the fluorescent material. This converts energy that would have been lost into productive light emission, dramatically improving energy utilization efficiency.
Solution Approach 2:
The delayed fluorescent material serves as an intermediary that mediates the conversion of triplet excitons to singlet excitons. This intermediary material enables efficient energy transfer from the triplet state to the fluorescent emitter, bridging the gap between the two states and maximizing energy utilization in the emission process.
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 configuration significantly improves the emitting efficiency and color purity of OLEDs by effectively utilizing both singlet and triplet excitons, leading to enhanced performance in organic light emitting display devices.
Implementation Method 1
the delayed fluorescent material's triplet exciton is converted to a singlet exciton
Implementation Method 2
The OLED emits light by injecting electrons from a cathode as an electron injection electrode and holes from an anode as a hole injection electrode into an emitting material layer (EML), combining the electrons with the holes, generating an exciton, and transforming the exciton from an excited state to a ground state
Data Source
AI summary
The present disclosure relates to an organic light emitting diode that includes a first electrode; a second electrode facing the first electrode; and a first emitting material layer including a first compound and a second compound and positioned between the first and second electrodes, wherein an overlap ratio between an absorption spectrum of the first compound and an emission spectrum of the second compound is equal to or greater than 35%, and an organic light emitting display including the organic light emitting diode.