Stacked Light-Emitting Elements for Efficient, Long-Life Displays
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Solution Overview
Problem
Existing display devices face challenges in achieving high light emission efficiency and a long lifespan for light-emitting elements with stacked structures, particularly in self-emissive display elements using organic compounds or quantum dots.
Innovation Solution
A light-emitting element design featuring a stacked structure with specific thickness relationships and materials, including electron transport layers and charge generation layers, where the sum of the first upper functional layer and n-type charge generation layer thickness exceeds the second upper functional layer thickness, and each layer includes electron transport materials with specific heteroaryl groups, enhancing light emission efficiency and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a stacked structure with multiple emission structures is used, then light emission efficiency is improved, but device complexity increases
Solution Approach 1:
The light-emitting element is divided into multiple emission structures (first emission structure and second emission structure) stacked in the thickness direction, with each structure containing emission layers, functional layers, and charge generation layers. This segmentation allows independent optimization of each emission structure while achieving high overall efficiency through multiple light-emitting interfaces.
Solution Approach 2:
Multiple emission structures are nested within a single light-emitting element device, with the first emission structure positioned below the second emission structure. Each emission structure contains nested functional layers (electron transport layers, hole transport layers, charge generation layers) that are integrated within the same device architecture, maximizing space utilization and light emission efficiency.
2Productivity
If specific thickness relationships between layers are maintained, then light emission efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise thickness parameters for different layers: the first upper functional layer is 50-200 nm, the n-type charge generation layer is 20-100 nm, and the second upper functional layer is 50-200 nm. These parameter ranges are optimized to balance light emission efficiency with manufacturing feasibility, ensuring that the sum of the first upper functional layer and n-type charge generation layer thickness exceeds the second upper functional layer thickness.
Solution Approach 2:
Different thickness specifications are applied to different layers based on their specific functions. The electron transport layers and hole transport layers have different thickness requirements optimized for their respective charge transport needs, while the charge generation layers have thicknesses optimized for charge carrier generation. This localized optimization allows high efficiency while maintaining manufacturing precision within achievable limits.
3Duration of action of stationary object
If electron transport materials with specific heteroaryl groups are used, then lifespan is improved, but material selection complexity increases
Solution Approach 1:
The patent employs composite material strategies by combining electron transport materials containing specific heteroaryl groups (such as triazole, tetrazole, pyrazole rings) with other functional materials in the emission structures. These composite material systems provide both the longevity benefits of stable heteroaryl-based electron transport and the functional performance needed for efficient light emission, thereby extending device lifespan while managing material complexity through targeted molecular design.
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 improved light emission efficiency and extended lifespan of the light-emitting elements, suitable for display devices requiring stable performance.
Implementation Method 1
the first upper functional layer, the second upper functional layer, and the n-type charge generation layer may each include an electron transport material
Implementation Method 2
a charge generation layer disposed between the lower emission structure and the upper emission structure, the charge generation layer including an n-type charge generation layer and a p-type charge generation layer
Implementation Method 3
a light-emitting element that exhibits improved light emission efficiency and a long lifespan
Data Source
AI summary
Embodiments provide a light-emitting element and an electronic device that includes the light-emitting element. The light-emitting element includes: a first electrode; a second electrode facing the first electrode; a lower emission structure disposed between the first electrode and the second electrode and including a first lower functional layer, a first emission layer, and a first upper functional layer; an upper emission structure disposed on the lower emission structure and including a second lower functional layer, a second emission layer, and a second upper functional layer; and a charge generation layer disposed between the lower emission structure and the upper emission structure and including an n-type charge generation layer and a p-type charge generation layer, wherein the light-emitting element satisfies Expression 1, which is explained in the specification:50 nm≥dTOP>dLOW>15 nm.[Expression 1]