OLED Quad Subpixel Lens Structure for White Light Extraction
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Solution Overview
Problem
Organic light emitting display devices face low light extraction efficiency and anode discontinuation or short-circuit defects between the anode and cathode within the contact hole of the planarization layer.
Innovation Solution
The device incorporates a substrate with a 2×2 matrix arrangement of sub-pixels, including a planarization layer with a concave lens-shaped portion in the white sub-pixel and varying thicknesses of the passivation layer under the contact hole to enhance light extraction efficiency and prevent anode discontinuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a planarization layer with a concave lens-shaped portion is added to improve light extraction efficiency, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The planarization layer incorporates a concave lens-shaped portion with a curved surface instead of a flat surface. This curvature acts as a microlens structure that focuses and extracts light more efficiently from the organic light emitting layer, directly improving light extraction efficiency while adding only a single layer component
Solution Approach 2:
The planarization layer serves multiple functions: it provides surface planarization for manufacturing, acts as an encapsulation layer for protection, and incorporates the concave lens-shaped portion for light extraction enhancement. By combining multiple functions into a single layer, device complexity is minimized while achieving multiple benefits
2Reliability
If the passivation layer thickness is increased to prevent anode discontinuation, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The passivation layer is designed with different thicknesses in different regions: a first thickness in the contact hole region to ensure anode continuity and prevent short-circuits, and a second thickness in other regions for proper encapsulation. This localized thickness variation allows each region to have the optimal thickness for its specific function
Solution Approach 2:
The passivation layer thickness parameter is changed spatially across the device structure. By controlling the thickness to be greater than a predetermined value specifically in the contact hole region, the anode continuity issue is resolved without requiring uniform thickness increase across the entire device, thus managing manufacturing precision requirements
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 improves light extraction efficiency of the white sub-pixel and suppresses anode discontinuation or short-circuit defects, leading to enhanced performance and reduced power consumption.
Implementation Method 1
the planarization layer has a concave portion of a lens shape in the fourth sub-pixel
Data Source
AI summary
An organic light emitting display device includes a substrate having a first sub-pixel, a second sub-pixel, a third sub-pixel and a fourth sub-pixel arranged in a quad type of a 2×2 matrix form, a first color filter disposed in the first sub-pixel, a second color filter disposed in the second sub-pixel, a third color filter disposed in the third sub-pixel, and a planarization layer covering the first to third color filters, wherein the planarization layer has a concave portion of a lens shape in the fourth sub-pixel, wherein the concave portion has a width greater than that of the fourth sub-pixel. Accordingly, the organic light emitting display device with improved light extraction efficiency of the fourth sub-pixel may be implemented.