OLED Directional Property Alignment for Charge Injection
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Solution Overview
Problem
The life of organic light emitting diodes (OLEDs) is limited by the interface characteristics between the organic light emitting layer and the common layers, leading to inefficient hole and electron injection, resulting in reduced device longevity.
Innovation Solution
The OLED structure includes a first common layer with a hole injection layer and a second common layer with an electron injection layer, both having the same directional properties as the organic light emitting layer, ensuring smooth charge injection and transportation, thereby extending the OLED's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common layers are disposed between electrodes and organic light emitting layer, then charge injection and transportation is improved, but interface characteristics deteriorate leading to reduced device life
Solution Approach 1:
The patent changes the directional property parameter of the common layers to match the organic light emitting layer. By adjusting this physical parameter (molecular orientation/directional property) of the first and second common layers to be the same as the organic light emitting layer, the interface characteristics are improved, charge accumulation is prevented, and device life is extended without adding structural complexity
2Productivity
If common layers with different directional properties are used, then device structure is simplified, but charge injection efficiency deteriorates
Solution Approach 1:
The patent optimizes the directional property parameter of the common layers to match the organic light emitting layer, thereby improving charge injection efficiency. The first common layer (hole injection layer) and second common layer (electron injection layer) are both configured to have the same directional property as the organic light emitting layer, ensuring efficient charge injection without complicating the overall layer structure
Data Source
AI summary
An organic light emitting diode includes a first electrode layer, a first common layer disposed on the first electrode layer, an organic light emitting layer disposed on the first common layer, a second common layer disposed on the organic light emitting layer, and a second electrode layer disposed on the second common layer. The organic light emitting layer and the first common layer have the same directional property. Since an injection/transportation of charge at an interface of the first common layer and the organic light emitting layer becomes smooth, charges are not accumulated at the interface. Thus, life of the organic light emitting diode is extended.