Top-Emitting LED Microcavity Wavelength Tuning
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Solution Overview
Problem
Conventional top-emitting OLEDs face challenges in efficiently adjusting the wavelength of light beams and achieving high light intensity, particularly in emitting RGB colors effectively.
Innovation Solution
A top-emitting light-emitting diode (LED) is designed with a glass substrate, a polysilicon layer, a white light emitting layer, and a transparent conductive layer, where sub-wavelength structures are arranged on the polysilicon layer, and the transparent conductive layer is formed over the white light emitting layer, creating a microcavity that adjusts the wavelength and enhances light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional top-emitting OLEDs use multiple layers (anodes, hole transport layer, emission layer, electron transport layer, cathode) to adjust wavelength, then color emission is achieved, but the structure complexity increases and manufacturing precision requirements increase
Solution Approach 1:
The patent extracts and eliminates the complex multi-layer structure (anodes, hole transport layer, electron transport layer, cathode) from conventional OLEDs, retaining only the essential components: substrate, light emitting layer, and transparent conductive layer. This simplification maintains the core light emission function while removing unnecessary structural complexity.
Solution Approach 2:
The patent inverts the conventional OLED structure by placing the transparent conductive layer on top of the light emitting layer, creating a top-emitting configuration. This structural inversion simplifies the device architecture while maintaining color emission capability through the transparent conductive layer's optical properties.
2Adaptability or versatility
If conventional OLEDs use e-beam evaporation to pattern hole transport layer with different thicknesses for RGB microcavity, then wavelength adjustment is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent changes the optical parameters of the transparent conductive layer (refractive index, thickness) to achieve wavelength adjustment for RGB emission. By controlling the thickness of the transparent conductive layer and utilizing its refractive index properties, the microcavity resonance conditions are tuned to emit different colors without requiring complex e-beam evaporation patterning.
3Adaptability or versatility
If conventional OLEDs use multiple ITO layers with different thicknesses for microcavity creation, then color emission is achieved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent extracts and eliminates the multiple ITO layers used in conventional OLEDs for microcavity creation, simplifying the structure to a single transparent conductive layer. This layer serves both as the electrode and as the optical cavity controller, reducing device complexity while maintaining color emission capability.
4Use of energy by moving object
If conventional OLEDs use semitransparent aluminum and silver layers as cathode, then electron injection is achieved, but light extraction efficiency decreases due to absorption
Solution Approach 1:
The patent replaces the complex semitransparent aluminum and silver cathode structure with a simpler transparent conductive layer that provides both electrical functionality and optical transparency. This substitution reduces light absorption losses while maintaining electron injection capability through the conductive properties of the transparent layer.
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 LED achieves improved light intensity and color emission by adjusting the microcavity thickness, specifically increasing blue and green light radiation intensity while maintaining red light intensity, and is suitable for RGB light beams through grating patterns, enhancing light extraction efficiency and color output.
Implementation Method 1
plural sub-wavelength structures are discretely arranged on a surface of the polysilicon layer at regular intervals... creating a microcavity that adjusts the wavelength
Implementation Method 2
a white light emitting layer... formed over the polysilicon layer and the plural sub-wavelength structures
Data Source
AI summary
A top-emitting light-emitting diode includes a glass substrate, a polysilicon layer, a white light emitting layer and a transparent conductive layer. The polysilicon layer is formed on a first surface of the glass substrate. Moreover, plural sub-wavelength structures are discretely arranged on a surface of the polysilicon layer at regular intervals. The white light emitting layer is formed over the polysilicon layer and the plural sub-wavelength structures. The transparent conductive layer is formed over the white light emitting layer.