Indium Zinc Oxide Interface Ratio for Blue Light Emission
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Solution Overview
Problem
Conventional light-emitting elements face challenges in achieving desired characteristics, particularly in maintaining low driving voltage while ensuring deep blue light emission and maintaining transparency and resistance in the transparent conductive layer.
Innovation Solution
A light-emitting element with a metal layer, a transparent conductive layer containing indium zinc oxide, and a light-emitting layer, where the zinc to indium ratio at the interface closer to the light-emitting layer is maintained at or below 0.25, and a manufacturing method involving the formation and oxidation of these layers to suppress zinc segregation and maintain optimal layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the transparent conductive layer contains indium zinc oxide with high zinc content to improve light emission characteristics, then deeper blue light emission is achieved, but zinc segregation occurs at the interface which increases driving voltage
Solution Approach 1:
The patent applies local quality by creating a compositional gradient within the transparent conductive layer. The zinc to indium ratio is controlled to be lower than or equal to 0.25 in the vicinity of the interface with the light-emitting layer, while other regions may have different compositions. This local variation in material composition prevents zinc segregation at the critical interface while maintaining overall light emission performance.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the zinc to indium ratio parameter in the transparent conductive layer. By setting this ratio to be lower than or equal to 0.25 at the interface region, the patent optimizes the balance between light emission characteristics and electrical stability, preventing harmful zinc segregation while maintaining desired optical properties.
2Productivity
If the transparent conductive layer thickness is reduced to improve device performance, then light emission efficiency improves, but transparency and resistance characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the composition parameter (zinc to indium ratio) in the transparent conductive layer. By controlling this ratio to be lower than or equal to 0.25 at the interface, the patent enables the layer to maintain appropriate transparency and resistance characteristics even at reduced thickness, thereby improving light emission efficiency without sacrificing electrical and optical performance.
3Reliability
If zinc segregation is suppressed to maintain low driving voltage, then interface stability improves, but light emission characteristics may deteriorate
Solution Approach 1:
The patent resolves this contradiction by applying local quality - different regions of the transparent conductive layer have different zinc to indium ratios optimized for their specific functions. The interface region has a lower ratio (≤0.25) to prevent zinc segregation and maintain stability, while other regions can have compositions optimized for light emission characteristics.
Solution Approach 2:
The patent uses parameter changes to balance interface stability and light emission by controlling the zinc to indium ratio parameter. By setting this parameter to be lower than or equal to 0.25 at the interface, the patent ensures interface stability while maintaining overall light emission performance through appropriate composition distribution.
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 enables the production of light-emitting elements that emit deeper blue light with suppressed driving voltage and maintains the transparency and resistance of the transparent conductive layer, achieving desired characteristics for organic EL elements and display devices.
Implementation Method 1
a ratio of zinc to indium in a vicinity of an interface of the transparent conductive layer is lower than or equal to 0.25
Implementation Method 2
oxidizing the metal layer
Data Source
AI summary
An organic EL element includes: a first electrode that is a metal layer; a transparent conductive layer containing indium zinc oxide; and a light-emitting layer, wherein the first electrode, the transparent conductive layer, and the light-emitting layer are stacked, and a ratio of zinc to indium in a vicinity of an interface of the transparent conductive layer is lower than or equal to 0.25, the interface being closer to the light-emitting layer.