OLED Cathode Auxiliary Electrode and Antireflection Layer
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Solution Overview
Problem
Conventional organic light emitting display panels, particularly top-emitting devices, face issues with low aperture ratio and non-uniform image quality due to high resistance and voltage drop caused by thin metal cathodes, leading to light loss and display brightness issues.
Innovation Solution
An organic light emitting display panel with a grid-like auxiliary electrode on a second substrate, electrically connected to the cathode, and an antireflection layer to absorb light rays, reducing resistance and voltage drop, and improving display uniformity and contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a thin metal cathode is used in a top-emitting device, then light transmittance is improved, but electrical resistance increases and voltage drop increases
Solution Approach 1:
The cathode is divided into two functional layers: a thin metal cathode layer (5-20 nm) for light transmittance and a transparent conductive oxide layer (50-200 nm) for electrical conductivity. This segmentation allows each layer to optimize its specific function without compromising the other.
Solution Approach 2:
The cathode uses a composite structure combining metal material (Al, Ag, Mg, Ca, Sm) with transparent conductive oxide material (ITO, IZO, TCO). This composite approach achieves both high light transmittance and low electrical resistance, resolving the contradiction between optical and electrical performance.
2Reliability
If the metal cathode thickness is increased, then electrical resistance decreases, but light transmittance decreases and display brightness decreases
Solution Approach 1:
The cathode functionality is segmented between two layers: the metal layer provides electrical conductivity with minimal thickness (5-20 nm) to maintain transmittance, while the transparent conductive oxide layer (50-200 nm) supplements electrical conductivity without blocking light.
Solution Approach 2:
The invention changes the thickness parameters of cathode layers from conventional single-layer thick metal (hundreds of nm) to a multi-layer structure with optimized thicknesses: metal layer 5-20 nm and TCO layer 50-200 nm, achieving optimal balance between conductivity and transmittance.
3Illumination intensity
If a transparent conductive oxide material like ITO is used for the cathode, then light transmittance is improved, but manufacturing complexity increases and organic layer damage occurs due to sputter process
Solution Approach 1:
The metal cathode layer serves as an intermediary between the organic light emitting layer and the transparent conductive oxide layer. It provides electrical connection to the organic layer while the TCO layer provides high transmittance, distributing the functional requirements across multiple materials.
Solution Approach 2:
The composite cathode structure combines metal material (deposited by thermal evaporation or sputtering) with transparent conductive oxide material (deposited by sputtering). This composite approach balances manufacturing considerations with performance requirements, using each material's strengths.
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 reduces voltage drop and improves display uniformity and contrast ratio by increasing electrical conductivity and absorbing light rays, enhancing the overall quality and brightness of the display panel.
Implementation Method 1
an antireflection layer formed on the auxiliary electrode for absorbing light rays directed to the auxiliary electrode
Implementation Method 2
a second substrate having at least one auxiliary electrode electrically connected to a cathode of the organic light emitting diode
Data Source
AI summary
The present disclosure relates to an organic light emitting display panel and a display apparatus. The organic light emitting display panel includes: a first substrate provided with a plurality of pixels each comprising an organic light emitting diode; a second substrate having at least one auxiliary electrode electrically connected to a cathode of the organic light emitting diode, each auxiliary electrodes being located on a side of the second substrate facing the first substrate and corresponding to a gap between adjacent pixels on the first substrate; and an antireflection layer formed on the auxiliary electrode for absorbing light rays directed to the auxiliary electrode. In the present disclosure, by the auxiliary electrode formed on the second substrate and electrically connected to the cathode on the first substrate, the voltage drop of the cathode may be significantly reduced, and the uniformity of the display brightness is improved. Meanwhile, by the antireflection layer formed on the auxiliary electrode, light leakage phenomenon due to reflection of a metal auxiliary electrode may be prevented, thereby improving contrast ratio of the display.