White OLED Charge Generation Layer Metal Content Control
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Solution Overview
Problem
Conventional organic light emitting devices face limitations in emission efficiency and lifespan, leading to abnormal light emission and increased driving voltage due to improper content of alkali metals or alkali earth metals in the charge generation layer.
Innovation Solution
A white organic light emitting device is designed with a charge generation layer containing a specific range of alkali metals or alkali earth metals, between 0.3% to 1.0% of the total volume, to prevent abnormal light emission, reduce driving voltage, and enhance device reliability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the content of alkali metal or alkali earth metal in the charge generation layer is increased to improve charge transfer efficiency, then the emission efficiency is improved, but abnormal light emission occurs and the device lifespan decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the metal content within 0.3-1.0% volume range and selecting specific metal types (Li, Na, K, Rb, Cs, Fr or their compounds) to optimize charge transfer efficiency while preventing abnormal light emission and extending device lifespan
Solution Approach 2:
The patent applies local quality by creating different charge generation layer compositions for different device regions or functions, using specific metal types and compounds tailored to particular performance requirements rather than uniform composition throughout
2Productivity
If the content of alkali metal or alkali earth metal in the charge generation layer is increased to improve charge transfer, then the emission efficiency is improved, but the driving voltage increases
Solution Approach 1:
The patent optimizes the balance between emission efficiency and driving voltage by controlling metal content within 0.3-1.0% volume range and selecting specific metal types with appropriate work functions, achieving improved charge transfer without excessive voltage increase
3Power
If the metal content in the charge generation layer is below the predetermined level, then the driving voltage is reduced, but the device cannot emit normal white light
Solution Approach 1:
The patent identifies and applies critical threshold parameters for metal content (0.3-1.0% volume range) that must be maintained to achieve both normal white light emission and acceptable driving voltage levels, preventing subthreshold operation
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 optimized metal content in the charge generation layer effectively prevents abnormal light emission, reduces driving voltage, and increases the lifespan of the organic light emitting device while improving its efficiency and reliability.
Implementation Method 1
A charge generation layer (CGL) is provided between the two light emitting units in order to generate and transfer a charge
Implementation Method 2
The generated electron is transferred to an n-type CGL (N-CGL) including an alkali metal by pumping
Implementation Method 3
An electron and a hole are injected into the organic emitting layer from the two electrodes and an exciton is formed by combining the electron and hole. Further, the organic light emitting device uses a principle in which a light is emitted when the exciton makes transitions from an excited state to a ground state
Data Source
AI summary
Provided is a white organic light emitting device which can improve abnormal light emission and efficiency and reliability of the device.A white organic light emitting device according to an exemplary embodiment of the present invention includes: a first light emitting unit including a first emitting layer between a first electrode and a second electrode; a second light emitting unit including a second emitting layer on the first light emitting unit; and a charge generation layer between the first light emitting unit and the second light emitting unit, and a volume of a metal in the charge generation layer is 1.0% or less of the total volume of the charge generation layer.