Organic Electroluminescent Device With Varying Electrode Thickness
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Solution Overview
Problem
Organic electroluminescent displays (OELDs) have limited lifetime due to the blue organic light emitting layer, and their light efficiency is not optimized, leading to reduced brightness and color reproduction.
Innovation Solution
The OELD is designed with pixel regions having first electrodes of varying thicknesses to maximize the micro cavity effect, incorporating a blue light emitting layer and a red/green light emitting layer with a charge generation layer, optimizing light paths and interference for improved color reproduction and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single uniform first electrode thickness is used across all pixel regions, then the device structure is simple and easy to manufacture, but the light emission efficiency and brightness are not optimized
Solution Approach 1:
The patent applies different first electrode thicknesses to different pixel regions (first, second, and third pixel regions have different thicknesses) to optimize light emission efficiency and brightness for each region, while still using a uniform manufacturing process for depositing the electrode material
2Device complexity
If only a blue light emitting layer is used, then the device structure is simple, but the lifetime is limited due to the blue organic light emitting material's shorter lifespan
Solution Approach 1:
The patent divides the light emitting layer into multiple segments: a blue light emitting layer and a red/green light emitting layer, where each segment has different lifetime characteristics, allowing the device to maintain functionality even when one layer degrades
Solution Approach 2:
The patent uses a composite structure combining blue light emitting material and red/green light emitting material in the same device, leveraging the complementary lifetime properties of different organic light emitting materials to extend overall device lifespan
3Device complexity
If the micro cavity effect is not optimized, then the device structure is simple, but the color reproduction and brightness are reduced
Solution Approach 1:
The patent optimizes the micro cavity effect by configuring different first electrode thicknesses in different pixel regions, creating localized optical cavities that enhance light emission efficiency and brightness for each region
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 enhances the lifetime of the OELD by reducing dependence on the blue layer's lifetime, increases light emission efficiency, and maximizes brightness and color reproduction by optimizing light paths and interference.
Implementation Method 1
first electrodes different in thickness in the respective pixel regions to maximize the micro cavity effect
Implementation Method 2
organic light emitting layer between the first and second electrodes... A current passing through the driving thin film transistor DTr is adjusted according to the data voltage applied to the driving thin film transistor DTr, and the current is applied to the organic light emitting diode E
Data Source
AI summary
An electroluminescent device includes: first to third pixel regions; a first electrode in each of the first to third pixel regions, wherein the first electrode of the third pixel region has a first thickness, the first electrode of the first pixel region has a second thickness less than the first thickness, and the first electrode of the second pixel region has a third thickness less than the second thickness; a second electrode in each of the first to third pixel regions; at least two electroluminescent units in each of the first and third pixel regions and disposed between the first electrode and second electrode, wherein one of the at least two electroluminescent units includes a blue light emitting layer and the other of the at least two electroluminescent units include a red/green light emitting layer; and a charge generation layer disposed between the at least two electroluminescent units.