OLED Blue TADF Layer Triplet Exciton Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current OLED devices have low light-emitting efficiency for blue light due to the use of blue fluorescent materials, which do not fully utilize triplet exciton energy, resulting in inefficient light emission.
Innovation Solution
An organic light-emitting device with a three-layer structure comprising a yellow light emitting layer and two blue light emitting layers, where one blue layer includes a blue thermally-activated delayed fluorescent material and the other includes a blue fluorescent material, enhancing light-emitting efficiency and reliability by utilizing triplet excitons for emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If blue fluorescent material is used in OLED devices, then the device structure is simple and easy to manufacture, but the light-emitting efficiency is low due to inability to utilize triplet excitons
Solution Approach 1:
The patent employs composite material strategy by combining blue fluorescent material with blue phosphorescent material in a single light-emitting layer. The fluorescent material provides structural simplicity and ease of manufacture, while the phosphorescent material contributes triplet exciton utilization capability. This composite approach allows the device to achieve high light-emitting efficiency without sacrificing manufacturing simplicity, as both materials work synergistically within the same layer structure.
Solution Approach 2:
The light-emitting layer is designed to perform multiple functions simultaneously: it serves as both a fluorescent emission layer and a phosphorescent emission layer. By incorporating both fluorescent and phosphorescent materials in the same layer, the structure achieves universal functionality that covers both singlet and triplet exciton utilization, eliminating the need for separate layers and maintaining manufacturing simplicity while boosting overall efficiency.
2Use of energy by moving object
If blue phosphorescent material is used to improve light-emitting efficiency, then the internal quantum efficiency reaches 100%, but the reliability and stability are insufficient
Solution Approach 1:
The patent modifies the material composition parameters by selecting specific blue phosphorescent materials with optimized characteristics and controlling their doping concentrations within precise ranges (5-20 wt%). It also adjusts the host material parameters to ensure appropriate energy levels and molecular weights. These parameter optimizations enable the phosphorescent material to achieve high efficiency while maintaining improved reliability and stability compared to conventional formulations.
3Device complexity
If triplet excitons are not utilized in fluorescent materials, then the device structure is simple, but 75% of energy is wasted and light-emitting efficiency is low
Solution Approach 1:
The patent converts the previously harmful or wasted triplet excitons into useful light-emitting resources. By incorporating phosphorescent material that can utilize triplet excitons for phosphorescence emission, the device transforms the 75% energy loss into productive light output. This approach maintains relatively simple device structure while dramatically reducing energy waste through the phosphorescence mechanism that exploits triplet state energy.
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 solution significantly improves light-emitting efficiency and extends the service life of OLED devices by enabling 100% internal quantum efficiency and higher color purity, with the blue thermally-activated delayed fluorescent material facilitating efficient conversion of triplet excitons to singlet excitons for enhanced light emission.
Implementation Method 1
the other one includes a blue thermally-activated delayed fluorescent material used as an auxiliary material between a host and a guest
Implementation Method 2
a phosphorescent material with singlet excitons and triplet excitons participating in light emission has been developed
Implementation Method 3
electrons and holes are injected into the organic light-emitting layer EML from the cathode CA and the anode AN respectively and are compounded to generate excitons which jump from an excitation state to a ground state to emit light
Data Source
AI summary
The present application discloses an organic light-emitting device and a display device. The organic light-emitting device comprises an anode, a cathode, and a first blue light emitting layer, a second blue light emitting layer and a yellow light emitting layer laminated between the anode and the cathode, wherein the yellow light emitting layer is arranged between the cathode and the first blue light emitting layer, and the first blue light emitting layer is arranged between the yellow light emitting layer and the second blue light emitting layer; and the yellow light emitting layer comprises a phosphorescent material, one of the first blue light emitting layer and the second blue light emitting layer comprises a blue fluorescent material, and the other one comprises a blue thermally-activated delayed fluorescent material used as an auxiliary material between a host and a guest.