OLED with segmented emissive layers and charge generating layer
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Solution Overview
Problem
Organic light emitting diodes (OLEDs) face challenges in achieving improved light emission efficiency and lifespan while maintaining color purity and viewing angle, particularly due to limitations in interlayer distance and the use of phosphorescent materials which can shorten the lifespan.
Innovation Solution
The OLED structure includes multiple light emitting layers with phosphorescent and fluorescent materials, charge generating layers, and specific hole and electron control layers, with a focus on optimizing the thickness of hole control layers and using charge generating layers to enhance light emission efficiency and lifespan, and a color control layer using quantum dots to improve color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent materials are used in the light emitting layer to improve light emission efficiency, then light emission efficiency is improved, but lifespan is shortened
Solution Approach 1:
The light emitting layer is divided into multiple sub-layers with different materials and functions. The first light emitting layer uses phosphorescent materials for high efficiency, while the second light emitting layer uses fluorescent materials for longer stability, segmenting the functional requirements across different layers
Solution Approach 2:
The patent employs composite material structures in the light emitting layers, combining phosphorescent and fluorescent materials in specific configurations, and using multiple organic compound layers with different properties to achieve both high efficiency and extended lifespan
2Stability of the object's composition
If the thickness of the hole control layer is increased to improve charge balance, then charge balance is improved, but device complexity increases
Solution Approach 1:
The patent optimizes the thickness parameter of the hole control layer to a specific range (100-900 Å) to achieve proper charge balance without excessive thickness, and adjusts the hole mobility parameter of the materials used to maintain charge balance with moderate layer thickness
Solution Approach 2:
The hole control layer is positioned specifically between the first electrode and the first light emitting layer where hole injection and transport are critical, providing localized charge control functionality rather than uniformly thick layers throughout the device
3Manufacturing precision
If multiple light emitting layers are added to improve color purity, then color purity is improved, but device complexity increases
Solution Approach 1:
The display device is segmented into multiple light emitting layers, each responsible for specific color emission characteristics, allowing independent optimization of each layer's material composition and thickness to achieve overall color purity
Solution Approach 2:
The charge generating layer and hole control layer serve multiple functions simultaneously - they manage charge transport between layers, control interlayer distance for optical resonance, and influence color emission characteristics, reducing the need for separate dedicated layers
4Use of energy by moving object
If the interlayer distance is optimized to improve light emission efficiency, then light emission efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines a specific interlayer distance range (100-900 Å) that optimizes optical resonance conditions for enhanced light emission efficiency, and uses material parameter adjustments to maintain this distance within manufacturing tolerances
Solution Approach 2:
The patent employs a charge generating layer that can be deposited in controlled thickness to establish the proper interlayer distance, and uses the optical resonance effect to recover and enhance light emission efficiency from the specific distance configuration
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 configuration results in improved light emission efficiency, extended lifespan, and enhanced color purity, as well as better optical viewing angles by optimizing the interlayer distances and using quantum dots for color control.
Implementation Method 1
a first light emitting layer between the first electrode layer and the second electrode layer and including a phosphorescent material
Implementation Method 2
a second light emitting layer between the first light emitting layer and the second electrode layer and including a fluorescent material
Implementation Method 3
a color control layer using quantum dots to improve color purity
Data Source
AI summary
An organic light emitting diode includes: a first electrode layer; a second electrode layer on the first electrode layer and facing the first electrode layer; a first light emitting layer between the first electrode layer and the second electrode layer and comprising a phosphorescent material; a first hole control layer between the first electrode layer and the first light emitting layer; a second light emitting layer between the first light emitting layer and the second electrode layer and comprising a fluorescent material; and a charge generating layer between the first light emitting layer and the second light emitting layer, the first hole control layer having a thickness equal to or greater than 100 angstroms and equal to or smaller than 900 angstroms.