Dual Emitting Layer OLED Structure for Higher Recombination Efficiency
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Solution Overview
Problem
Existing organic electroluminescence devices face challenges in enhancing performance, particularly in terms of luminous efficiency and overall device performance.
Innovation Solution
The device incorporates a first emitting layer with a first host material and a second emitting layer in direct contact, utilizing specific compounds represented by formulas (1) and (2) to enhance luminous efficiency and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single emitting layer is used in the organic EL device, then the device structure is simple, but the luminous efficiency and emission characteristics are limited due to inefficient hole and electron recombination
Solution Approach 1:
The emitting layer is divided into two distinct layers: a first emitting layer containing a first host material and a second emitting layer containing a second host material. This segmentation allows each layer to be optimized for specific charge carrier recombination, improving overall recombination efficiency while maintaining a relatively simple overall device structure.
Solution Approach 2:
Each emitting layer is assigned different local properties through the selection of specific host materials with complementary characteristics. The first host material is optimized for one type of charge carrier recombination while the second host material is optimized for the other type, creating local quality differences that enhance overall device performance.
2Device complexity
If conventional host materials are used in the organic EL device, then the device structure is simple, but the luminous efficiency and emission characteristics are insufficient
Solution Approach 1:
The invention employs composite host material systems where the first host material and second host material work synergistically in their respective layers. This composite approach combines the advantages of different material classes to achieve superior luminous efficiency and emission characteristics that cannot be obtained with single conventional materials.
Solution Approach 2:
The invention optimizes specific molecular parameters of the host materials, including the structure of the group represented by formula (11) with specific substituents (R101-R110), to tune the electronic and optical properties. By changing these molecular parameters, the device achieves enhanced luminous efficiency while maintaining structural simplicity.
3Device complexity
If the first emitting layer and second emitting layer are not in direct contact, then the device structure allows for intermediate layers, but the triplet exciton transfer efficiency is reduced
Solution Approach 1:
The first emitting layer and second emitting layer are placed in direct contact without intermediate layers, merging the two functional regions into a closely integrated structure. This direct contact enables efficient triplet exciton transfer between the layers through wavefunction overlap, maximizing energy utilization and luminous efficiency.
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 results in an organic electroluminescence device with improved luminous efficiency and overall performance, addressing the limitations of existing technologies.
Implementation Method 1
When a voltage is applied to an organic EL device, holes and electrons are injected from an anode and a cathode, respectively, into an emitting layer. The injected holes and electrons are recombined in the emitting layer to form excitons.
Implementation Method 2
According to the electron spin statistics theory, singlet excitons and triplet excitons are generated at a ratio of 25%:75%.
Data Source
AI summary
An organic electroluminescence device includes an anode, a cathode, a first emitting layer, and a second emitting layer provided between the first emitting layer and the cathode in which the first emitting layer contains a first compound represented by a formula (1) below as a first host material, the first compound containing at least one group represented by a formula (11) below, the second emitting layer contains a second compound represented by a formula (2) below as a second host material, and the first emitting layer and the second emitting layer are in direct contact with each other.