Transparent Cathode Sandwich Structure for OLED Luminance
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Solution Overview
Problem
Conventional transparent cathodes in organic light emitting displays have insufficient light transmittance, leading to low luminance, and reducing the silver layer thickness to improve transmittance increases power consumption due to decreased electric conductivity.
Innovation Solution
A cathode structure with a sandwiched configuration of transparent oxide layers, such as indium tin oxide (ITO), interposed between metal layers like silver, enhances both electric conductivity and light transmittance through quantum tunneling, allowing for higher luminance with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the silver layer thickness is decreased to improve light transmittance, then light transmittance is improved, but electric conductivity is reduced and power consumption increases
Solution Approach 1:
The patent employs a composite cathode structure consisting of multiple metal layers (silver, aluminum, or magnesium) combined with transparent oxide layers (ITO, IZO, or ZnO:Al) in a sandwiched configuration. This composite structure enables the cathode to simultaneously achieve high light transmittance (75% or more) and appropriate electric conductivity, resolving the contradiction between improving light transmission and maintaining electrical performance without increasing power consumption.
Solution Approach 2:
The patent transitions from a conventional single-layer or simple multi-layer cathode to a complex sandwiched multi-layer structure with alternating metal and transparent oxide layers. This dimensional complexity in layering allows the system to optimize both optical and electrical properties simultaneously, achieving high light transmittance while maintaining sufficient conductivity through the combined effect of multiple materials.
2Illumination intensity
If the silver layer thickness is decreased to increase light transmittance, then light transmittance is improved, but luminance is reduced due to insufficient conductivity
Solution Approach 1:
The sandwiched structure combining metal layers with transparent oxide layers creates a composite cathode that achieves both high light transmittance (75% or more) and appropriate electric conductivity. This resolves the contradiction by allowing the cathode to transmit more light while maintaining sufficient conductivity to support high luminance output in top emission OLED displays.
3Ease of manufacture
If a conventional cathode structure is used, then manufacturing is simple, but light transmittance is insufficient (63% average)
Solution Approach 1:
The patent implements a sandwiched multi-layer cathode structure with alternating metal and transparent oxide layers. While this composite structure is more complex than conventional single-layer cathodes, it achieves the critical improvement of light transmittance to 75% or more, which is essential for high-performance top emission OLED displays.
Solution Approach 2:
The patent adopts a multi-layer sandwiched architecture that adds structural dimensionality compared to conventional cathodes. This layered configuration enables the system to achieve superior light transmittance (75% or more) by combining the optical transparency of oxide layers with the electrical conductivity of metal layers in an alternating sequence.
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 sandwiched structure achieves over 75% light transmittance while maintaining appropriate electric conductivity, significantly improving luminance and reducing power consumption in top emission organic light emitting displays.
Implementation Method 1
enhances both electric conductivity and light transmittance through quantum tunneling
Data Source
AI summary
A top emission type organic light emitting display includes an organic light emitting diode in which an anode, a light emitting layer and a transparent cathode are successively deposited. The cathode has a sandwiched structure in which a transparent oxide layer is inserted between the metal layers. Exemplary embodiments of the cathode of the present invention have better electric conductivity than a conventional cathode of an organic light emitting diode device, and thus has lower power consumption than a conventional top emission organic light emitting display with similar light transmission.