Semiconductor Light-Emitting Element with Sinusoidal Convexo-Concave Structures
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Solution Overview
Problem
Semiconductor light-emitting elements face challenges in enhancing light extraction efficiency due to total reflection at interfaces, leading to reduced emission intensity and orientation, and scattering issues when used as display light sources.
Innovation Solution
A semiconductor light-emitting element with a light-emitting layer having a first and second convexo-concave structure, coated with optical functional films that include reflecting layers to adjust light reflection and emission directions, and a light-transmissive sealing resin for reliability, enhancing emission intensity and orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a convexo-concave structure having triangular waves-shaped cross-section is formed on the light-emitting surface of the semiconductor light-emitting element, then total reflection on the interface between the light-emitting surface and the sealing resin is suppressed and light extraction efficiency is enhanced, but undulations are generated in the orientation of emission light due to discrete tilt angles
Solution Approach 1:
The patent changes the geometric parameters of the convexo-concave structure from triangular waves to sinusoidal shape, and optimizes the pitch and depth parameters to achieve both high light extraction efficiency and smooth angular distribution of emission light without undulations
Solution Approach 2:
The patent applies different convexo-concave structures to different surfaces: a first convexo-concave structure on the light-emitting surface for light extraction, and a second convexo-concave structure on the opposite surface for controlling internal reflection, with each structure optimized for its specific function
2Loss of energy
If a convexo-concave structure having triangular waves-shaped cross-section is formed on the light-emitting surface of the sealing resin, then total reflection on the interface between the sealing resin and the air is suppressed and light extraction efficiency is enhanced, but scattering of external light reflection occurs and contrast is lowered
Solution Approach 1:
The patent changes the cross-sectional shape from triangular waves to sinusoidal form and optimizes the pitch parameter to be equal to or less than 10 μm, which suppresses visible scattering while maintaining anti-reflection effectiveness, thereby preserving image contrast
Solution Approach 2:
The patent uses sinusoidal curved surfaces instead of angular triangular waves, creating smooth continuous curvature that reduces light scattering while maintaining the anti-reflection function, thus preserving contrast in display applications
3Loss of energy
If the tilt angle of the emitting surface is not correctly selected, then emission light that exceeds a critical angle of total reflection on the interface between the sealing resin and the air increases, but the light is trapped inside the sealing resin and light extraction efficiency cannot be enhanced
Solution Approach 1:
The patent optimizes the pitch and depth parameters of the convexo-concave structure to control the tilt angles of emitted light, ensuring that most light rays fall within the critical angle for total internal reflection at the sealing resin-air interface, thereby maximizing light extraction efficiency
Solution Approach 2:
The patent uses simulation and measurement feedback to optimize the geometric parameters of the convexo-concave structure, adjusting the pitch and depth to achieve the desired light emission angle distribution that maximizes extraction while maintaining simplicity
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 solution effectively increases emission intensity and improves light distribution properties by optimizing light reflection and emission directions, while maintaining reliability through the use of a light-transmissive sealing resin.
Implementation Method 1
an optical functional film that coats the second surface and the peripheral surface and includes a reflecting layer capable of reflecting light emitted by the light-emitting layer
Implementation Method 2
A factor to lower the light extraction efficiency of such a semiconductor light-emitting element is light trapping due to total reflection on an interface between a light-emitting surface and a sealing resin
Data Source
AI summary
A semiconductor light-emitting element according to an embodiment of the present technology includes a first electrode, a second electrode, a light-emitting layer constituted by a semiconductor, and an optical functional film. The light-emitting layer includes a first surface that is connected to the first electrode and has a first convexo-concave structure, a second surface that is connected to the second electrode, has a second convexo-concave structure, and is opposite to the first surface, and a peripheral surface that continuously connects the first surface and the second surface to each other. The optical functional film coats the second surface and the peripheral surface and includes a reflecting layer capable of reflecting light emitted by the light-emitting layer.