OLED Device with Segmented Light Emitting Units and Charge-Generating Layer
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Solution Overview
Problem
Existing organic light emitting diode (OLED) devices face limitations in displaying stable white light due to inefficiencies in blue luminous efficiency, particularly as display sizes increase, and the use of fine shadow masks for depositing emission layers becomes impractical.
Innovation Solution
The OLED device incorporates a first light emitting unit with a blue emission layer and alkali metal complex compounds for improved charge mobility, combined with a second light emitting unit that emits white light by stacking red and green emission layers, using charge-generating and injection layers to enhance efficiency and color characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fine shadow mask is used to deposit emission layers in each sub-pixel, then color display capability is improved, but manufacturing complexity and cost increase significantly for large display devices
Solution Approach 1:
The device is divided into separate first and second light emitting units with distinct functions. The first unit deposits blue emission layer only, while the second unit deposits red and green emission layers. This segmentation eliminates the need for complex fine shadow masks for each sub-pixel, simplifying the manufacturing process for large displays while maintaining color display capability.
Solution Approach 2:
A charge-generating layer is introduced as an intermediary between the two light emitting units. This layer facilitates charge separation and transport, enabling the first light emitting unit to efficiently deposit blue excitons while the second unit handles red and green excitons, achieving color display without complex masking structures.
2Ease of manufacture
If white light is emitted by sequentially accumulating red, blue, and green emission layers using an open mask, then manufacturing is simplified, but color characteristics and efficiency deteriorate due to blue light emitting material limitations
Solution Approach 1:
The light emitting units are segmented into a first unit dedicated to blue emission and a second unit for red and green emission. This segmentation allows optimization of each unit's charge transport layers for its specific color requirements, improving blue luminous efficiency and overall color characteristics while maintaining the manufacturing simplicity of open mask deposition.
Solution Approach 2:
Different charge transport layers are used in the first and second light emitting units, with each layer optimized for its specific function. The first unit uses charge transport materials optimized for blue emission, while the second unit uses materials optimized for red and green emission, improving local efficiency and overall color characteristics.
3Reliability
If blue light emitting efficiency is improved through material optimization, then white light stability is improved, but device complexity increases
Solution Approach 1:
The charge transport layers are segmented into distinct first and second charge transport layers, each optimized for their respective light emitting unit. This segmentation improves blue luminous efficiency and white light stability by ensuring optimal charge transport in each unit, while the modular structure keeps device complexity manageable through functional separation.
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 improves driving voltage, current efficiency, electric power efficiency, external quantum efficiency, and blue light emission, enabling stable white light display with enhanced color characteristics and luminance.
Implementation Method 1
emits light when electrons injected from one electrode are combined with holes injected from the other electrode and thus forms excitons and releases energy
Implementation Method 2
emits a white light by combining the blue light emitted from the first light emitting unit with the red light and the green light
Implementation Method 3
a charge-generating layer interposed between the first electrode and the second electrode
Data Source
AI summary
An organic light emitting diode device includes a first electrode and a second electrode facing each other, a charge-generating layer interposed between the first electrode and the second electrode, a first light emitting unit that emits blue and is interposed between the first electrode and the charge-generating layer, and a second light emitting unit that emits white by combining the blue and is interposed between the second electrode and the charge-generating layer. The first light emitting unit includes a blue emission layer, a first charge transport layer disposed on one side of the blue emission layer and including an alkali metal complex compound and a first charge transport material, and a second charge transport layer disposed on one side of the first charge transport layer and including the alkali metal complex compound and a second charge transport material that has different charge mobility from the first charge transport material.