Charge Generation Layer Leakage Current in OLED Displays
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Solution Overview
Problem
Light emitting display devices experience lateral leakage current due to high mobility charge generation layers, causing adjacent sub-pixels to turn on and emit light unintentionally, which affects light emission efficiency and image quality.
Innovation Solution
A light emitting display device structure is implemented with a connection electrode connected to both n-type and p-type charge generation layers, allowing for the discharge of accumulated charges through a reset voltage, preventing lateral leakage current by creating paths for charge dissipation across different polarities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a charge generation layer with high mobility is commonly provided in sub-pixels, then light emission efficiency is increased, but lateral leakage current is generated causing adjacent sub-pixels to turn on unintentionally
Solution Approach 1:
The patent extracts the charge generation layer from the common layer structure and provides it separately in each sub-pixel. This is achieved by forming the charge generation layer only in regions where emission layers are formed, thereby preventing lateral leakage current while maintaining light emission efficiency in active sub-pixels.
Solution Approach 2:
The patent applies local quality by making the charge generation layer present only in specific regions (where emission layers are formed) rather than uniformly across all sub-pixels. This localized approach ensures high mobility charges are available where needed for light emission while preventing leakage in inactive sub-pixels.
2Device complexity
If common layers are commonly provided in all sub-pixels, then device structure is simplified, but turned-off sub-pixels receive voltage from adjacent turned-on sub-pixels causing light leakage
Solution Approach 1:
The patent extracts the charge generation layer function from the common layers and implements it through separate emission layers in each sub-pixel. This eliminates the voltage coupling between adjacent sub-pixels that causes light leakage, while the overall device structure remains relatively simple through this modular approach.
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 prevents lateral leakage current, ensuring that sub-pixels remain turned off and maintaining high light emission efficiency by discharging accumulated charges, thereby improving image quality and reducing unwanted light emission.
Implementation Method 1
a connection electrode connected to the charge generation layer, to which a reset voltage is applied, thereby preventing lateral leakage current
Data Source
AI summary
A light emitting display device according to an aspect of the present disclosure includes a substrate including a display area including a plurality of sub-pixels and a non-display area, a plurality of first electrodes respectively provided in the plurality of sub-pixels, a second electrode facing the plurality of first electrodes and extending over the entire display area and a part of the non-display area, an interlayer including a plurality of stacks provided between the plurality of first electrodes and the second electrode and a charge generation layer between the plurality of stacks, and a connection electrode connected to the charge generation layer. The charge generation layer includes an n-type charge generation layer and a p-type charge generation layer, and the n-type charge generation layer includes a first connection part connected to the connection electrode and the p-type charge generation layer includes a second connection part connected to the connection electrode.