Flexible OLED Pixel Structure With Bottom Metal Light Shielding
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Solution Overview
Problem
Flexible OLED displays face challenges in maintaining the characteristics of driving transistors due to light exposure, which can alter their performance and functionality.
Innovation Solution
A bottom metal layer is strategically disposed around the driving transistor between the substrate and the polycrystalline semiconductor layer, blocking light and maintaining the transistor's characteristics by floating between the driving transistor and other transistors, and being covered by the barrier layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a flexible substrate is used for OLED display, then thickness and weight are reduced and flexibility is achieved, but light can penetrate through the substrate and alter the characteristics of driving transistors
Solution Approach 1:
A bottom metal layer is introduced as an intermediary component between the flexible substrate and the driving transistor. This metal layer acts as a light-blocking barrier that prevents light from reaching and altering the transistor characteristics, while allowing the flexible substrate to maintain its weight-reduced and flexible properties.
Solution Approach 2:
The solution adds a new dimensional element (the bottom metal layer) to the existing structure. By placing this light-blocking layer in the vertical stacking sequence between the substrate and transistor, the patent resolves the light penetration issue without compromising the horizontal flexibility or weight advantages of the flexible substrate.
2Reliability
If the bottom metal layer is disposed around the driving transistor, then light-induced changes in transistor characteristics are prevented, but device structure becomes more complex
Solution Approach 1:
The bottom metal layer is merged with the existing pixel structure by integrating it into the substrate stack. Rather than adding a completely separate component, the metal layer is incorporated as part of the layered structure, sharing space and functions with surrounding pixel elements to minimize overall complexity.
Solution Approach 2:
The bottom metal layer serves multiple functions: it blocks light from reaching the transistor, provides structural support within the pixel, and can potentially serve as an electrical connection element. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
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 configuration effectively prevents light-induced changes in the driving transistor's characteristics, ensuring consistent performance and functionality even under flexible substrate conditions.
Implementation Method 1
A bottom metal layer is strategically disposed around the driving transistor between the substrate and the polycrystalline semiconductor layer, blocking light and maintaining the transistor's characteristics
Data Source
AI summary
An embodiment of a display device includes a display panel having a flexible characteristic and a rear passivation layer disposed on a rear surface of the display panel and including an opening, wherein a pixel is formed in an area of the display panel corresponding to the opening. The display panel includes: a flexible substrate including a polyimide layer and a barrier layer disposed on the polyimide layer; a driving transistor and a fifth transistor disposed on the substrate and including a polycrystalline semiconductor layer; a light emitting diode receiving an output current of the driving transistor; and a bottom metal layer disposed between the polyimide layer and the polycrystalline semiconductor layer in a cross-sectional view and disposed around a channel of the driving transistor in a plan view.