Light-Emitting Device Capping Layer for Balanced Green Light Extraction
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Solution Overview
Problem
Existing light-emitting devices face challenges in achieving both high frontal and lateral luminescence efficiency simultaneously, particularly in the green wavelength range of 520 nm to 550 nm, due to limitations in light extraction and emission spectrum control.
Innovation Solution
Incorporating a capping layer with an amine-containing compound, such as benzoxazole, benzthiazole, or naphthooxazole groups, and specific ligand structures for the iridium emitter, which enhances light extraction and controls the emission spectrum to achieve balanced frontal and lateral luminescence efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional light-emitting devices use standard emission layers and capping layers, then manufacturing is simpler, but both frontal and lateral luminescence efficiency cannot be optimized simultaneously
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive index of the capping layer material and adjusting the emission wavelength of the emitter to fall within specific ranges (refractive index: 1.7-2.0, emission wavelength: 520-550nm). This optimization of physical parameters enables simultaneous improvement of both frontal and lateral luminescence efficiency while maintaining manufacturing feasibility through standard deposition processes.
Solution Approach 2:
The patent employs composite materials by combining a specific emitter material (with refractive index 1.7-2.0) with a capping layer material having a controlled refractive index ratio. This composite structure creates an optimized optical interface that enhances light extraction in both frontal and lateral directions, resolving the contradiction between manufacturing simplicity and luminescence efficiency.
2Stability of the object's composition
If the emission wavelength is fixed in the green range, then color consistency is maintained, but light extraction efficiency varies between frontal and lateral directions
Solution Approach 1:
The patent applies local quality by designing the capping layer with specific optical properties (refractive index of 1.7-2.0) that are locally optimized for the green emission wavelength range. This localized optimization at the capping layer interface enables efficient light extraction in both frontal and lateral directions while maintaining color consistency, addressing the contradiction between color stability and light extraction efficiency.
3Adaptability or versatility
If conventional capping layers are used without specific refractive index control, then material selection is broader, but frontal and lateral luminescence efficiency are unbalanced
Solution Approach 1:
The patent applies parameter changes by establishing a specific refractive index range (1.7-2.0) for the capping layer material. This parameter specification narrows the material selection to optimized candidates while enabling simultaneous optimization of both frontal and lateral luminescence efficiency, resolving the contradiction between material versatility and luminescence performance.
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 proposed design achieves excellent frontal and lateral luminescence efficiency concurrently, allowing for the production of high-quality electronic apparatuses with improved light emission characteristics.
Implementation Method 1
the value of ratio of CIEy to reflective index (RCR value) of the first light extracted to the outside through the capping layer
Implementation Method 2
light extraction and emission spectrum control
Implementation Method 3
Carriers, such as the holes and electrons, recombine in the emission layer to produce excitons. These excitons are transitioned from an excited state to a ground state to thereby generate light
Data Source
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AI summary
A light-emitting device (10) and an electronic apparatus including the same are provided. The light-emitting device includes a first electrode (110), a second electrode (150) facing the first electrode, an interlayer (130) between the first electrode and the second electrode and including an emission layer, and a capping layer (170). The emission layer includes a first emitter, the first emitter emits first light having a first emission spectrum, the capping layer is in the path on which the first light travels, an emission peak wavelength of the first light is from about 520 nm to about 550 nm. The first emitter includes iridium, the capping layer includes an amine-containing compound, and the value of ratio of CIEy to reflective index (RCR value) of the first light extracted to the outside through the capping layer is 38 or less, and the RCR value is calculated according to CIEy / R(cap) x 100.