OLED Side Reflective Layer Lateral Light Extraction
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Solution Overview
Problem
Conventional OLEDs suffer from reduced luminescent efficiency due to light loss from random diffusion and ineffective light transmission through the reflective anode layer.
Innovation Solution
The implementation of a side reflective layer surrounding the organic light-emitting layer, formed by physical or chemical vapor deposition, which includes a reflective metal layer or a three-layer laminated structure with transparent metal oxide layers, enhances light reflection and exit efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflective anode layer is used to reflect light emitted by the luminescent layer, then the luminescent brightness is increased, but some light is randomly diffused and cannot be transmitted through the effective emission area and direction, reducing luminescent efficiency
Solution Approach 1:
The patent introduces a side reflective layer that extends the light reflection function from the traditional planar anode interface into the lateral dimension. This side reflective layer is positioned at the edge of the luminescent layer and reflects light that would otherwise be lost laterally, directing it toward the effective emission area. This dimensional extension of the reflective structure resolves the contradiction by capturing light in previously unused spatial directions while maintaining the brightness enhancement from the main reflective anode.
Solution Approach 2:
The side reflective layer acts as an intermediary element between the luminescent layer and the ambient environment. It mediates the interaction by intercepting light that escapes laterally from the luminescent layer and redirecting it toward the effective emission area. This intermediary structure prevents direct light loss to the surroundings while maintaining the beneficial light reflection from the main anode, thus resolving the energy loss issue without compromising brightness.
2Productivity
If the side reflective layer is positioned close to the organic light-emitting layer to maximize light reflection, then light exit efficiency is improved, but the risk of electrical short circuit and device reliability decreases
Solution Approach 1:
The insulating layer serves as an intermediary element between the side reflective layer and the organic light-emitting layer. It physically separates these two components to prevent direct contact that would cause electrical short circuits, while still allowing the side reflective layer to effectively reflect light from the luminescent layer. The insulating layer thus mediates between the conflicting requirements of close proximity for light reflection and separation for electrical isolation, enabling high light exit efficiency while maintaining device reliability.
Solution Approach 2:
The insulating layer is strategically positioned only where needed - between the side reflective layer and the organic light-emitting layer at their interface region. This localized application of insulation provides electrical isolation precisely where the risk of short circuit exists, while leaving other regions of the device structure unchanged. This local quality approach maintains device reliability without unnecessarily increasing overall device complexity or reducing light reflection efficiency in other areas.
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 significantly increases the luminescent efficiency of OLEDs by effectively reflecting lateral light, improving light exit and brightness.
Implementation Method 1
the anode layer and the side reflective layer are capable of reflecting light emitted from the light-emitting layer such that the light leaves from the light exiting area
Implementation Method 2
the side reflective layer is formed by physical or chemical vapor deposition
Data Source
AI summary
The present application discloses an OLED with an improved structure, comprising a reflective anode layer, a transparent cathode layer, an organic light-emitting layer sandwiched between the anode layer and the cathode layer, and a side reflective layer surrounding the organic light-emitting layer and forming a light exiting area together with the anode layer, wherein the light emitted from the light-emitting layer is reflected by both of the anode layer and the side reflective layer, and then leaves from the light exiting area. According to the present disclosure, the lateral light is reflected by the side reflective layer arranged around the organic light-emitting layer, such that the luminescent efficiency of the OLED with said improved structure can be significantly increased.