Groove-Based Reflective Layer for OLED Light Extraction
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Solution Overview
Problem
Top-emission organic light-emitting displays face challenges in achieving high brightness due to low light extraction efficiency, as a significant amount of light is lost by being emitted downward or sideways rather than being extracted effectively towards the top.
Innovation Solution
The display device incorporates a groove portion in the first overcoat layer with a reflective layer and a color filter, where the light emitted from the organic light-emitting diode is reflected upward by the reflective layer, and a second overcoat layer smooths out irregularities, ensuring that the light is efficiently extracted and emitted towards the top, with the groove portion's slope optimized for maximum light reflection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional flat structure is used without groove portions, then the device complexity is low, but the light extraction efficiency is poor causing low brightness
Solution Approach 1:
The first overcoat layer is segmented into multiple regions including groove portions and flat portions, creating a non-uniform surface structure. This segmentation allows different regions to serve different functions: groove portions for light reflection and flat portions for other device functions, thereby improving light extraction efficiency without requiring complete structural redesign
Solution Approach 2:
The invention introduces vertical dimension variations by creating groove portions with specific depths and slopes in the overcoat layer. This three-dimensional structuring transforms the previously two-dimensional flat surface, enabling light to be reflected upward at controlled angles and improving extraction efficiency in the vertical direction
2Loss of energy
If light is emitted in all directions from the organic light-emitting diode, then the light emission is uniform, but a significant amount of light is lost by being emitted downward or sideways rather than being extracted effectively towards the top
Solution Approach 1:
The reflective layer, positioned at the bottom of the groove portions, converts harmful downward-emitted light that would otherwise be lost into beneficial upward-directed light. By reflecting this previously wasted light back through the organic light-emitting diode structure, the device recovers energy and improves overall light extraction efficiency
Solution Approach 2:
Different regions of the device are given different optical properties: groove portions with reflective layers are designed to reflect and redirect light upward, while flat portions maintain their original light emission characteristics. This local differentiation optimizes light extraction in specific areas without compromising the overall device structure
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 improves light extraction efficiency, reducing light loss and increasing the overall brightness of the display by ensuring that more light is directed upwards, enhancing the display's performance.
Implementation Method 1
a reflective layer disposed on the first overcoat layer including the inside of the groove portion
Data Source
AI summary
A display device is provided that can increase brightness by improving light extraction efficiency. The display device can include a thin-film transistor disposed on a substrate, a first overcoat layer disposed on the thin-film transistor and including a groove portion, a reflective layer disposed on the first overcoat layer including the inside of the groove portion, a color filter disposed on the reflective layer and located in the groove portion, a second overcoat layer disposed on the color filter and the reflective layer, a first electrode disposed on the second overcoat layer and connected to the thin-film transistor, a bank layer disposed on the first electrode and including an open portion exposing the first electrode, an organic layer disposed on the bank layer and the first electrode, and a second electrode disposed on the organic film layer.