Organic Light-Emitting Device with Asymmetric Donor-Acceptor Layers
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Solution Overview
Problem
Existing organic light-emitting devices face low efficiency and stability due to carrier imbalance, which limits their development, especially in blue sub-pixels where only 25% of singlet excitons are utilized, leading to high power consumption and inefficiency.
Innovation Solution
An organic light-emitting device with a light-emitting layer comprising a donor and acceptor layer using thermally activated delayed fluorescence material, where the donor layer is thicker than the acceptor layer, and both may be doped with fluorescent materials, along with exciton limiting layers to enhance exciton recombination and balance carriers, utilizing a reverse intersystem-crossing process to maximize carrier utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a traditional blue fluorescent structure is adopted for blue sub-pixels, then the device can be fabricated with conventional materials, but the internal quantum efficiency is limited to 25% due to only singlet excitons being utilized
Solution Approach 1:
The patent changes the physical parameter of exciton utilization from 25% (singlet only) to 100% (both singlet and triplet) by introducing TADF materials with reverse intersystem crossing capability, transforming the efficiency parameter without changing the fundamental fluorescent emission mechanism
Solution Approach 2:
The patent employs composite material structure by combining TADF materials (which enable triplet exciton utilization) with conventional fluorescent emitters, creating a hybrid system that achieves both high efficiency and compatibility with existing fabrication processes
2Productivity
If TADF material is used in the light-emitting layer to achieve 100% internal quantum efficiency, then both singlet and triplet excitons can be utilized, but carrier imbalance occurs causing reduced efficiency and stability
Solution Approach 1:
The patent applies local quality by creating spatially differentiated regions within the light-emitting layer: the donor layer (thicker, 10-30 nm) primarily hosts holes and TADF materials, while the acceptor layer (thinner, 10-20 nm) primarily hosts electrons, with each region optimized for its specific carrier type to prevent carrier imbalance
Solution Approach 2:
The patent segments the light-emitting layer into functionally distinct donor and acceptor sub-layers with different thicknesses and material compositions, allowing independent optimization of hole and electron management regions to maintain carrier balance while achieving high exciton utilization
3Reliability
If the donor light-emitting layer thickness is increased to maintain carrier balance, then exciton recombination area is enlarged, but the device structure becomes more complex
Solution Approach 1:
The patent optimizes the thickness parameter of the donor layer (10-30 nm) to be greater than or equal to the acceptor layer (10-20 nm), creating an asymmetric thickness ratio that naturally enhances exciton recombination area and maintains carrier balance without requiring additional complex structural elements
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 enhances the internal quantum efficiency to 100% and prevents device aging by balancing electrons and holes, ensuring full energy utilization and reducing energy loss.
Implementation Method 1
A thermally activated delayed fluorescence (TADF) material is a new type of pure organic electronic material, which can simultaneously use singlet and triplet excitons generated by electrical excitation to achieve a theoretical internal quantum efficiency of 100%
Implementation Method 2
utilizing a reverse intersystem-crossing process to maximize carrier utilization
Data Source
AI summary
The present application discloses an organic light-emitting device and a display device, which include a light-emitting layer. The light-emitting layer includes a donor light-emitting layer and an acceptor light-emitting layer, wherein at least one film layer of the donor light-emitting layer and the acceptor light-emitting layer adopts a thermally activated delayed material.