Light Emitting Device Side Wall Refractive Index for Light Extraction
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Solution Overview
Problem
Conventional light emitting devices face limitations in improving light extraction efficiency, particularly with the miniaturization of light emitting elements, which leads to issues like color mixing and reduced efficiency in light condensation.
Innovation Solution
A light emitting device with a matrix arrangement of elements on a semiconductor substrate, featuring a stack structure including electrodes and protective films, and a side wall formed from a material with a different refractive index that extends from the upper surface of the second electrode to the light emitting layer, functioning as a lens to guide light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light emitting elements are miniaturized to improve display resolution, then pixel density increases, but light extraction efficiency deteriorates and color mixing occurs
Solution Approach 1:
The patent applies local quality by creating a side wall structure with different refractive index material specifically at the lateral boundaries of each pixel. This localized structural modification enables effective light extraction enhancement at the pixel level without affecting adjacent pixels, thereby preventing color mixing while maintaining high display resolution.
Solution Approach 2:
The patent transitions from two-dimensional planar light extraction to three-dimensional light management by introducing a vertical side wall structure. The side wall extends from the light emitting layer downward, creating a third dimension for light extraction that increases the effective extraction area without increasing the pixel footprint, thus improving light extraction efficiency while maintaining miniaturization.
2Ease of manufacture
If conventional structures are used without side walls, then manufacturing is simpler, but light extraction efficiency is limited
Solution Approach 1:
The patent applies parameter changes by modifying the refractive index parameter through the introduction of side wall material with a different refractive index from the surrounding medium. This parameter change creates refractive index contrast that enhances light extraction efficiency through total internal reflection at the side wall interfaces, overcoming the limitations of conventional uniform structures.
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
Enhances light extraction efficiency by preventing light from passing through adjacent color filters and ensuring proper condensation by the intended lens, thereby reducing color mixing and improving overall light emission intensity.
Implementation Method 1
a side wall that is formed of a material having a refractive index different from that of a material forming the first protective film and covering at least part of a side surface of the stack
Data Source
AI summary
Provided is a light emitting device including a plurality of light emitting elements (300) that is arranged in a matrix on a semiconductor substrate (200), in which each of the light emitting elements provided to be covered with a first protective film includes a stack that includes a first electrode (302), a light emitting layer (304) provided on the first electrode, a second electrode (306) provided on the light emitting layer, and a second protective film (308) provided on the second electrode, and a side wall (310) that is formed of a material having a refractive index different from that of a material forming the first protective film and covering at least part of a side surface of the stack, in which the side wall extends from a position above an upper surface of the second electrode to a position below an upper surface of the light emitting layer, downward in a stacking direction.