OLED Emission Layer with Substituted Anthracene Host
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Solution Overview
Problem
Current light-emitting devices face challenges in achieving high luminescence efficiency and long lifespan due to limitations in viewing angles, contrast ratios, and response times, particularly in the design of the emission layer and electrode structures.
Innovation Solution
A light-emitting device is designed with a specific interlayer structure comprising a first and second emission layer, where the second host is a substituted anthracene compound with a lower unoccupied molecular orbital (LUMO) energy level than the first host, enhancing exciton density and efficiency through triplet-triplet fusion, and using density functional theory (DFT) to determine energy levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional emission layer structure is used, then the device structure is simple, but the luminescence efficiency is low
Solution Approach 1:
The emission layer is divided into multiple sub-layers (first emission layer, second emission layer, third emission layer) with different host materials and triplet energy levels. This segmentation allows optimized exciton management and triplet-triplet fusion in each sub-layer, improving overall luminescence efficiency while maintaining manageable structural complexity
Solution Approach 2:
Each emission sub-layer is assigned specific local properties: the first emission layer uses a host with higher triplet energy, the second emission layer uses a substituted anthracene compound with intermediate triplet energy, and the third emission layer uses a host with lower triplet energy. This local differentiation optimizes exciton distribution and radiative decay pathways throughout the emission layer
2Loss of energy
If the LUMO energy levels of host materials are not optimized, then the material selection is simple, but the triplet exciton conversion efficiency is low
Solution Approach 1:
The patent systematically varies the LUMO energy level parameter across different host materials in the emission layers. By selecting hosts with progressively different LUMO levels (first host, substituted anthracene compound, third host), the invention optimizes electron distribution and triplet exciton conversion efficiency without requiring complex external controls
Solution Approach 2:
The patent replaces mechanical or physical structural complexity with energy level design. Instead of using complex device architectures or additional components to enhance triplet exciton conversion, the invention achieves this through careful selection and arrangement of materials with specific LUMO energy levels, substituting a materials-science approach for a device-engineering approach
3Speed
If a single emission layer is used, then the device structure is simple, but the response time is slow
Solution Approach 1:
The emission layer is segmented into multiple functional sub-layers that can simultaneously process different aspects of exciton recombination and light emission. This parallel processing architecture enables faster overall response time while keeping each individual sub-layer relatively simple in structure
Solution Approach 2:
The patent transitions from a single-dimensional emission layer to a multi-dimensional layered structure. By adding the vertical dimension of multiple emission sub-layers with different energy level characteristics, the system achieves faster response times through distributed exciton processing without requiring lateral expansion or complex lateral structures
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 improves luminescence efficiency and extends the lifespan of the light-emitting device by increasing triplet exciton conversion to singlet excitons, thereby enhancing light emission.
Implementation Method 1
enhancing exciton density and efficiency through triplet-triplet fusion
Implementation Method 2
The holes and the electrons recombine in the emission layer to produce excitons. When the excitons transition from an excited state to a ground state light is emitted from the device.
Data Source
AI summary
A light-emitting device and an electronic apparatus including the light-emitting device. The light-emitting device includes: a first electrode and a second electrode each having a surface opposite the other; and an interlayer disposed between the first electrode and the second electrode, wherein the interlayer includes an emission layer and a hole transport region, the hole transport region is disposed between the first electrode and the emission layer. The emission layer includes a first emission layer and a second emission layer, the first emission layer is disposed between the hole transport region and the second emission layer, wherein the first emission layer includes a first host and a first light-emitting material, and the second emission layer includes a second host and a second light-emitting material. The second host is a substituted anthracene compound, and the first host and the second host are different from each other. A lowest unoccupied molecular orbital (LUMO) energy level of the second host is less than a LUMO energy level of the first host, and each of the LUMO energy level of the first host and the LUMO energy level of the second host has a negative value and is determined using a density functional theory (DFT) method.