Tandem OLED Charge Generation Layer Mixed Conductive Composite
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Solution Overview
Problem
Tandem Organic Light Emitting Diodes (OLEDs) face issues with uniformity, low penetrability, and lateral conductivity due to excessively thin or thick metal layers, which affect their functionality, especially in large-sized panels.
Innovation Solution
A tandem OLED structure incorporating a charge generation layer made of a mixed conductive layer with a high conductivity material (≥10^3 S/cm) and a low conductivity material (≤10^-6 S/cm) in a specific weight percentage ratio, along with an electron injection layer, to achieve a moderate thickness and conductivity, thereby addressing the issues of uniformity and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal layer is made extremely thin to achieve ideal filming capability, then the penetrability is improved, but the uniformity deteriorates and the tandem OLED may fail to function properly
Solution Approach 1:
The patent applies composite materials by creating a mixed conductive layer composed of multiple materials with different conductivities (at least one material with conductivity greater than 10³ S/cm and at least one material with conductivity less than 10⁻⁶ S/cm). This composite structure enables the layer to achieve both adequate penetrability through the high-conductivity material and uniformity through the low-conductivity material, resolving the technical contradiction between these two properties.
2Manufacturing precision
If the metal layer is made thicker to improve uniformity, then the manufacturing precision is improved, but the penetrability is reduced
Solution Approach 1:
The mixed conductive layer uses composite materials where high-conductivity materials (such as metals or metal oxides) provide penetrability while low-conductivity materials (such as organic compounds) provide uniformity. This composite approach allows the layer to be thick enough for uniformity while maintaining adequate penetrability through the conductive components.
3Manufacturing precision
If the metal layer is made even thicker to further improve uniformity, then the manufacturing precision is improved, but lateral conductivity problems occur
Solution Approach 1:
The composite structure of the mixed conductive layer prevents excessive lateral conductivity by combining high-conductivity materials with low-conductivity materials. The low-conductivity components restrict unwanted lateral charge transport while the high-conductivity components ensure sufficient vertical charge generation, thus eliminating the harmful lateral conductivity effect while maintaining uniformity.
Data Source
AI summary
A tandem organic light emitting diode and a preparation method thereof are provided. The tandem organic light emitting diode includes: at least two light-emitting units (11, 12); a charge generation layer (21) disposed between the light emitting units (11, 12); wherein, the charge generation layer (21) includes a mixed conductive layer (211), and the mixed conductive layer (211) is made by mixing at least one material having a conductivity greater than 103 S/cm with a content of 5˜95 wt % and at least one material having a conductivity less than 10−6 S/cm with a content of 95˜5 wt %. The tandem organic light emitting diode is applicable in a display device.