Auxiliary Cathode Parallel Connection for OLED Brightness Uniformity
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Solution Overview
Problem
Large-sized top-emitting OLED display panels face issues with high cathode sheet resistance, leading to voltage drop and uneven brightness, which increases power consumption and affects the normal operation of thin film transistors.
Innovation Solution
The implementation of an auxiliary cathode in a non-display area connected in parallel with the main cathode reduces cathode resistance, improving brightness uniformity and using self-assembled materials for patterning the auxiliary electrode and organic covering layer without fine masks to lower production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode is made thinner to prevent influence on light extraction rate, then light transmission is improved, but cathode sheet resistance increases
Solution Approach 1:
The patent employs a composite cathode structure consisting of multiple metal layers (such as Al/LiF/Al or Mo/Al/Mo) with different properties. This composite structure achieves both high transparency and low sheet resistance by combining materials with complementary characteristics - some layers provide transparency while others provide conductivity, resolving the contradiction between light transmission and electrical conductivity.
2Illumination intensity
If the cathode sheet resistance is reduced to improve brightness uniformity, then brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The cathode is segmented into multiple thin functional layers rather than using a single thick layer. This segmentation allows each layer to perform a specific function (some optimized for transparency, others for conductivity), achieving low sheet resistance and uniform brightness while maintaining a manageable structural complexity through systematic layering.
3Area of stationary object
If large-sized panels are manufactured to increase display area, then display area is increased, but voltage drop becomes more serious
Solution Approach 1:
The patent addresses the voltage drop issue in large-sized panels by transitioning from a single-plane cathode to a multi-layer stacked cathode structure. This dimensional change in the cathode architecture provides additional pathways for current flow, effectively reducing the electrical resistance across the large display area and minimizing voltage drop without compromising the increased display area.
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
This solution effectively reduces cathode resistance, alleviates voltage drop issues, and enhances brightness uniformity across the panel, while reducing production costs through innovative patterning methods.
Implementation Method 1
the auxiliary electrode is connected in parallel with the second electrode
Implementation Method 2
the cathode sheet resistance of the devices is too large, a voltage drop (IR-drop) of the panel is serious
Implementation Method 3
vacuum evaporating an organic material on the second electrode
Implementation Method 4
the organic material in the non-display area absorbs high energy to sublimate into a gaseous state, gaseous molecules are condensed into a film
Implementation Method 5
gaseous molecules are condensed into a film in the light transmitting area
Implementation Method 6
irradiating the mask with a laser, wherein light is transmitted through the light transmitting area
Data Source
AI summary
The present disclosure provides a display panel and a manufacturing method of the display panel. The display panel includes an array substrate, a first electrode, a pixel definition layer, an organic functional layer, a second electrode, a covering layer, and an auxiliary electrode. By arranging an auxiliary cathode in a non-display area and using a parallel connection of the auxiliary cathode and a cathode, a cathode resistance of devices is reduced to relieve an IR-drop phenomenon and improve a brightness uniformity of the panel. The present disclosure provides the manufacturing method of the display panel. An organic material can be patterned to form the covering layer without using a fine mask, and a metal material can be patterned to form the auxiliary electrode by utilizing characteristics of self-assembled materials, thereby reducing production costs.