OLED Device With Varying Hole Transport Layer Thickness
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Solution Overview
Problem
Organic light emitting display (OLED) devices have shorter lifespan and lower efficiency compared to other flat panel display devices, necessitating improvements in both lifespan and efficiency.
Innovation Solution
The OLED device incorporates multiple light emitting units with varying thicknesses of hole transport layers, optimized to enhance hole mobility and control electroluminescence, along with charge generation layers to improve electron and hole supply, resulting in a structure where the total thickness of the hole transport layer in the first light emitting unit is greater than that of the second, and further optimized with additional layers for enhanced efficiency and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional OLED structure is used, then device can be manufactured with standard processes, but lifespan is short and efficiency is low
Solution Approach 1:
The OLED device is divided into multiple light emitting units (first, second, and third light emitting units) with different structures. Each unit contains specific layers (hole transport layers, emission layers, electron transport layers) configured to emit light at different wavelengths. This segmentation allows optimization of each unit's function while collectively improving overall device lifespan and efficiency.
Solution Approach 2:
Different regions of the device have different layer configurations. The first light emitting unit has a first hole transport layer with specific thickness, the second unit has a second hole transport layer with different thickness, and the third unit has a third hole transport layer. This local quality variation optimizes hole mobility and electroluminescence in each region, thereby extending overall device lifespan.
2Productivity
If standard hole transport layer thickness is used, then manufacturing is simplified, but hole mobility is insufficient and efficiency is low
Solution Approach 1:
The patent varies the thickness parameter of hole transport layers across different light emitting units. The first hole transport layer has a first thickness, the second hole transport layer has a second thickness, and the third hole transport layer has a third thickness. This parameter change optimizes hole mobility and electroluminescence efficiency in each unit, significantly improving overall luminous efficiency.
3Illumination intensity
If driving current is increased to maintain brightness, then brightness is maintained, but lifespan decreases and efficiency reduces
Solution Approach 1:
The device segments the light emitting function across multiple units with different emission characteristics. This allows the device to achieve desired brightness through combined emission from multiple units rather than overdriving a single unit, thereby maintaining brightness while reducing stress on individual components and extending lifespan.
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 optimizes luminous efficiency, reduces driving voltage, and extends the lifespan of the OLED device while maintaining brightness at lower current levels, achieving enhanced viewing angles and efficiency compared to conventional OLEDs.
Implementation Method 1
a hole transport layer supplying holes from the first electrode to the first emission layer
Implementation Method 2
a first electron transport layer supplying electrons from the charge generation layer to the first emission layer
Implementation Method 3
a first light emitting unit including a first emission layer formed between the first electrode and the charge generation layer
Data Source
AI summary
An organic light emitting display device includes first and second electrodes facing each other on a substrate, a charge generation layer formed between first and second electrodes, a first light emitting unit including a first emission layer formed between the first electrode and the charge generation layer, a hole transport layer supplying holes from the first electrode to the first emission layer, and a second light emitting unit including a second emission layer formed between the second electrode and the charge generation layer, a hole transport layer supplying holes from the charge generation layer to the second emission layer, wherein a total thickness of the hole transport layer of the first light emitting unit is greater than that of the hole transport layer of the second light emitting unit.