Organic Light-Emitting Device Emission Layer Segmentation
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Solution Overview
Problem
Current organic light-emitting devices face challenges in achieving balanced low gradation image quality, luminescence efficiency, lifespan, and roll-off ratio, with existing designs struggling to optimize the performance of emission layers and dopant combinations.
Innovation Solution
A light-emitting device is designed with a structure featuring a first and second emission layer, each comprising a host and a dopant, where the dopants are transition metals and the host compositions are optimized to satisfy specific permanent dipole moment and weight fraction conditions, enhancing luminescence efficiency and lifespan through precise dopant and host combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single emission layer with conventional dopant is used, then the device structure is simple, but the luminescence efficiency and lifespan are insufficient
Solution Approach 1:
The emission layer is divided into multiple emission layers (first emission layer and second emission layer), each containing different dopants (first dopant and second dopant) with distinct photoluminescence spectra. This segmentation allows optimization of luminescence efficiency and lifespan through tailored dopant-host interactions in each layer, resolving the contradiction between structural simplicity and reliability.
2Illumination intensity
If dopant concentration is increased to improve luminescence efficiency, then brightness increases, but roll-off ratio worsens
Solution Approach 1:
Different dopants are used in different emission layers, with each dopant optimized for specific local requirements. The first dopant in the first emission layer and the second dopant in the second emission layer have different photoluminescence spectra and dipole moments, allowing localized optimization of luminescence efficiency while controlling roll-off ratio through precise dipole moment matching with respective hosts.
Solution Approach 2:
The patent optimizes the permanent dipole moments of dopants and hosts by selecting specific materials with predetermined dipole moment values. By controlling the dipole moment parameters (PDM(D1), PDM(D2), PDM(H1), PDM(H2)) to satisfy specific relationships, the patent achieves improved luminescence efficiency and reduced roll-off ratio through parameter optimization rather than simply increasing dopant concentration.
3Ease of manufacture
If uniform host material is used throughout the emission layer, then manufacturing is easier, but low gradation image quality deteriorates
Solution Approach 1:
The emission layer is segmented into multiple layers with different host materials (first host and second host), each optimized for specific gradation requirements. This allows precise control of light emission characteristics in different regions, improving low gradation image quality while maintaining manufacturing feasibility through systematic material selection.
Solution Approach 2:
The patent uses composite material systems where each emission layer contains a specific host-dopant combination. The first emission layer uses first host with first dopant, and the second emission layer uses second host with second dopant. These composite material systems are designed to satisfy specific dipole moment relationships, enabling improved image quality through material composition optimization.
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 optimized emission layer structure improves luminescence efficiency, power efficiency, and lifespan, while reducing roll-off ratio and achieving better low-gradation emission characteristics, resulting in a high-performance light-emitting device with improved overall performance.
Implementation Method 1
the first dopant capable of emitting a first light having a first photoluminescence spectrum, the second dopant capable of emitting second light having a second photoluminescence spectrum
Implementation Method 2
Expression 1 and Expression 2 are satisfied, wherein in Expression 1, PDM(D1) is a permanent dipole moment of the first dopant, PDM(H1) is a permanent dipole moment average value of the first host, and in Expression 2, PDM(D2) is a permanent dipole moment of the second dopant, PDM(H2) is a permanent dipole moment average value of the second host
Data Source
AI summary
A light-emitting device and an electronic apparatus including the same. The light-emitting device includes a first electrode, a second electrode facing the first electrode, and an interlayer arranged between the first electrode and the second electrode, the interlayer includes a first emission layer and a second emission layer, the first emission layer includes a first host and a first dopant capable of emitting a first light, the first host includes m1 hosts, m1 is an integer of 1 or more, and when m1 is 2 or more, two or more hosts are present in the first emission layer and are different from the other, the second emission layer includes a second host and a second dopant capable of emitting a second light, the second host includes m2 hosts, m2 is an integer of 1 or more, and when m2 is 2 or more, two or more hosts are present in the second emission layer and are different from the other, the first dopant includes a first transition metal, the second dopant includes a second transition metal different from the first transition metal, and Expression 1 and Expression 2 are satisfied and provided in the present specification.