Transparent OLED Display Substrate with Light Extraction Layers
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Solution Overview
Problem
The transmittance of OLED transparent display apparatus is reduced due to cathodes being arranged on the entire surface, affecting the transparent display effect.
Innovation Solution
A display substrate design with a first and second light extraction layer having higher refractive indices than the second electrode, positioned in non-opening areas to enhance light refraction and increase overall transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cathodes are arranged on the entire surface of the OLED display, then the light emission and electrical function are improved, but the transmittance of non-opening areas is reduced, affecting the transparent display effect
Solution Approach 1:
The patent changes the refractive index parameter of the electrode structure by introducing light extraction layers with refractive indices (1.8-2.5) higher than the second electrode (1.4-1.6). This parameter modification enables the non-opening areas to transmit more light while maintaining the electrical function of the cathode, directly resolving the contradiction between light emission reliability and transmittance.
Solution Approach 2:
The patent introduces light extraction layers as intermediary structures between the light-emitting layer and the second electrode. These intermediary layers with higher refractive indices facilitate light extraction into the non-opening areas, enabling the cathode to maintain its electrical function while improving light transmission through the electrode structure.
2Illumination intensity
If light extraction layers with higher refractive indices are added, then the transmittance of non-opening areas is improved, but the device structure becomes more complex
Solution Approach 1:
The patent resolves the structure complexity issue by arranging light extraction layers in specific spatial dimensions - the first light extraction layer is positioned between the light-emitting layer and second electrode in the vertical dimension, while the second light extraction layer is arranged on the surface of the second electrode. This dimensional arrangement achieves enhanced light extraction without requiring complex lateral structures.
Solution Approach 2:
The patent applies light extraction layers selectively in non-opening areas rather than uniformly across the entire display. The first light extraction layer is arranged in at least part of the non-opening area, and the second light extraction layer's orthographic projection completely covers the first light extraction layer. This localized application improves transmittance where needed while minimizing overall structural 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
The design significantly improves the transmittance of the non-opening areas, enhancing the transparent display effect by refracting more light at the electrode interfaces.
Implementation Method 1
a refractive index of the first light extraction layer is greater than a refractive index of the second electrode... a refractive index of the second light extraction layer is greater than the refractive index of the second electrode... significantly improves the transmittance of the non-opening areas, enhancing the transparent display effect by refracting more light at the electrode interfaces
Data Source
AI summary
The display substrate includes: a base substrate including sub-pixel regions with opening regions and non-opening regions; light-emitting devices each including a first electrode, a light-emitting layer and a second electrode; a first light extraction layer between a light-emitting layer and a second electrode; and a second light extraction layer on the side of the second electrode away from the first light extraction layer. The first light extraction layer is provided in at least part of a non-opening region, and the refractive index of the first light extraction layer is greater than the refractive index of the second electrode. An orthographic projection of the second light extraction layer on the base substrate completely covers an orthographic projection of the first light extraction layer on the base substrate, and the refractive index of the second light extraction layer is greater than the refractive index of the second electrode.