OLED Anode Amorphous Oxide Layer Gas Barrier
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Solution Overview
Problem
Conventional organic light emitting diode displays face issues with silver in the reflective metal layer binding to external gases, leading to potential short-circuiting due to grain boundaries in the transparent conductive layer, which affects display reliability and efficiency.
Innovation Solution
Incorporating an amorphous oxide layer with a lower work function than the upper transparent conductive layer, made of materials like silver, copper, or aluminum, and formed at low temperatures, to prevent gas permeation and enhance hole injection while minimizing light loss, with a thickness of 1 nm to 5 nm, and a light-transmissive second electrode for improved reliability and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent conductive layer with grain boundaries is used, then light transmission is achieved, but gas permeation occurs leading to short-circuiting
Solution Approach 1:
An amorphous oxide layer is introduced as an intermediary barrier between the reflective metal layer and the transparent conductive layer. This intermediate layer has lower work function than the transparent conductive layer, providing both gas tightness and favorable electrical characteristics for hole injection, thereby preventing gas permeation while maintaining light transmission and electrical functionality.
Solution Approach 2:
The first electrode is constructed as a composite structure comprising multiple layers: reflective metal layer, amorphous oxide layer, and transparent conductive layer. Each layer contributes specific properties - the reflective metal provides light reflection, the amorphous oxide provides gas barrier and low work function, and the transparent conductive layer provides light transmission and conductivity, achieving overall performance optimization.
2Reliability
If the amorphous oxide layer thickness is increased, then gas barrier performance improves, but light transmission decreases
Solution Approach 1:
The thickness of the amorphous oxide layer is precisely controlled within the range of 1 nm to 5 nm. This parameter optimization ensures sufficient gas barrier performance while maintaining adequate light transmission. The thin film thickness provides effective gas tightness due to the amorphous structure without significantly attenuating the emitted light.
3Reliability
If a material with lower work function is used for the amorphous oxide layer, then hole injection is enhanced, but manufacturing complexity increases
Solution Approach 1:
The work function of the amorphous oxide layer is controlled to be lower than that of the transparent conductive layer, creating a favorable energy level alignment for hole injection from the organic emission layer. This parameter optimization enhances charge injection efficiency while the low deposition temperature (below 100°C) maintains manufacturing simplicity.
Solution Approach 2:
The amorphous oxide layer is deposited at temperatures below 100°C, which prevents thermal damage to underlying layers and allows for simple manufacturing processes. The low temperature deposition maintains the amorphous structure and low work function characteristics while avoiding complex high-temperature processing equipment requirements.
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 solution effectively prevents gas permeation and short-circuiting, enhances hole injection, and minimizes light loss, resulting in improved display quality and reliability for organic light emitting diode displays.
Implementation Method 1
the amorphous oxide layer may be in contact with the upper transparent conductive layer... effectively prevents gas permeation and short-circuiting
Implementation Method 2
The amorphous oxide layer may have a lower work function than the upper transparent conductive layer... enhances hole injection
Implementation Method 3
a first electrode including a reflective metal layer of a light-reflective metal... Light emitted from the organic emission layer is reflected by the reflective metal layer
Implementation Method 4
The amorphous oxide layer may be formed at a temperature below 100° C.
Data Source
AI summary
An organic light emitting diode includes a first electrode including a reflective metal layer of a light-reflective metal, an upper transparent conductive layer on the reflective metal layer, and an amorphous oxide layer on the upper transparent conductive layer, an organic emission layer on the first electrode, and a second electrode on the organic emission layer.