Dual Emission Layer OLED Structure for Stable Color Output
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Solution Overview
Problem
Existing organic light-emitting devices face issues with process stability and color deviation during mass production due to variations in resonance distances affecting emission color and luminescence efficiency, leading to inconsistent side luminance ratios and curvature of CIEx-luminescence efficiency curves.
Innovation Solution
The introduction of a light-emitting device with a reflective electrode and a dual emission layer structure, where the first emission layer emits light with a shorter wavelength than the second, reducing resonance distance variations and enhancing the microcavity effect to improve luminescence efficiency and side luminance ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single emission layer is used in organic light-emitting devices, then the device structure is simple, but color deviation and luminescence efficiency vary during mass production due to resonance distance variations
Solution Approach 1:
The emission layer is divided into multiple emission layers (first emission layer and second emission layer), each with different emission peak wavelengths. This segmentation allows independent optimization of each layer's properties, reducing the impact of resonance distance variations on overall device performance and ensuring color consistency during mass production.
Solution Approach 2:
The patent uses a composite emission layer structure combining different organic compounds with specific emission characteristics. The first emission layer contains compounds with emission peak wavelengths of 480-520 nm, while the second emission layer contains compounds with emission peak wavelengths of 560-600 nm, creating a composite structure that stabilizes color output.
2Loss of energy
If resonance distance is increased to improve luminescence efficiency, then light extraction is enhanced, but color deviation increases due to microcavity effect variations
Solution Approach 1:
The patent changes the emission peak wavelength parameters of different emission layers to create a wavelength distribution that reduces microcavity effect sensitivity. By selecting compounds with specific emission ranges (480-520 nm for first layer, 560-600 nm for second layer), the device maintains stable color output across varying resonance distances.
3Productivity
If the emission layer structure is simplified for easier manufacture, then production is faster, but side luminance ratio becomes inconsistent across devices
Solution Approach 1:
The emission layer is segmented into multiple functional layers with distinct emission characteristics. This segmentation provides a straightforward manufacturing process while ensuring consistent side luminance ratio across devices, as each layer contributes specifically to overall color stability.
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 design stabilizes the manufacturing process by reducing color deviation and enhancing luminescence efficiency, resulting in improved side luminance ratios and a gentler curvature of the CIEx-luminescence efficiency curve, thus ensuring consistent performance across mass-produced devices.
Implementation Method 1
the first electrode is a reflective electrode
Implementation Method 2
enhancing the microcavity effect to improve luminescence efficiency
Implementation Method 3
λP(1) and λP(2) are evaluated from photoluminescence spectra measured for a first film and a second film, respectively
Implementation Method 4
λP(3) is evaluated from an electroluminescence spectrum of the light-emitting device
Data Source
AI summary
Provided are 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 emission layer between the first electrode and the second electrode, wherein the first electrode is a reflective electrode, the emission layer includes i) a first emission layer, ii) a second emission layer, or a combination thereof, wherein when the first emission layer and the second emission layer are both present, then the second emission layer is located between the first emission layer and the second electrode, the first emission layer includes a first compound capable of emitting first light having a first spectrum, λP(1) is an emission peak wavelength (nm) of the first spectrum, the second emission layer includes a second compound capable of emitting second light having a second spectrum, λP(2) is an emission peak wavelength (nm) of the second spectrum, the emission layer may emit third light having a third spectrum, λP(3) is an emission peak wavelength (nm) of the third spectrum, λP(1) is less than λP(2), |λP(1)−λP(2)| is greater than 0 nm and less than or equal to 30 nm, and each of |λP(2)−λP(3)| and |λP(3)−λP(1)| is greater than or equal to 0 nm and less than or equal to 30 nm.