Blue OLED Display Stack for Uniform Brightness and Lower IR Drop
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Solution Overview
Problem
In display devices with limited space for capacitors, brightness uniformity is affected, and the higher impedance of transparent conductive materials in organic light emitting diodes (OLEDs) causes IR drop issues, which can be exacerbated by interference between capacitors and auxiliary electrodes.
Innovation Solution
A display device configuration that includes a substrate, inorganic layers, a thin film transistor, a storage capacitor, organic layers, a light emitting diode, sealing layers, a wavelength conversion layer, and a blue light blocking layer, with specific arrangements to minimize interference and enhance voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the space for capacitor is limited, then device area is reduced, but brightness uniformity deteriorates
Solution Approach 1:
The patent positions the storage capacitor in the vertical dimension by placing its second electrode between the third inorganic layer and the first organic layer, rather than expanding the capacitor horizontally. This vertical stacking approach reduces the horizontal area occupied by the capacitor while maintaining its capacitance function, thereby preserving brightness uniformity without increasing device area.
2Illumination intensity
If transparent conductive material is used in OLED cathode, then device transparency is improved, but voltage distribution deteriorates due to higher impedance
Solution Approach 1:
The patent introduces an auxiliary electrode as an intermediary component between the transparent conductive cathode and the ITO layer. This auxiliary electrode serves as a mediator to improve voltage distribution by providing additional conductive pathways, compensating for the high impedance of the transparent conductive material while maintaining device transparency.
3Reliability
If auxiliary electrodes are added to reduce IR drop, then voltage distribution is improved, but interference with capacitor occurs
Solution Approach 1:
The patent resolves the interference issue by positioning the auxiliary electrode and capacitor in different vertical layers. The auxiliary electrode is placed between the ITO layer and the third inorganic layer, while the capacitor's second electrode is positioned between the third inorganic layer and the first organic layer. This vertical separation in the layer structure eliminates electrical interference between the auxiliary electrode and capacitor, allowing both components to function simultaneously without compromising voltage distribution or creating component interference.
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 proposed configuration improves brightness uniformity and reduces IR drop issues by optimizing the placement and materials of the inorganic and organic layers, while minimizing interference between capacitors and auxiliary electrodes.
Implementation Method 1
a wavelength conversion layer (166)
Implementation Method 2
a blue light blocking layer (170)
Data Source
AI summary
A display device includes a first inorganic layer disposed on a substrate, a thin film transistor disposed on a first inorganic layer including a semiconductor, a gate, a source and a drain, a storage capacitor including a first electrode and a second electrode, a first organic layer disposed on the thin film transistor and including a contact via, a second inorganic layer disposed between the gate and the semiconductor, a third inorganic layer disposed between the source and the gate, a light emitting diode including an anode electrically connected with the source through the contact via, a cathode and a light emitting layer, a first sealing layer disposed on the light emitting diode, a wavelength conversion layer disposed on the first sealing layer, and a blue light blocking layer disposed on the wavelength conversion layer. The second electrode is disposed between the third inorganic layer and the first organic layer.