Light-Emitting Element Roughness Control for Light Extraction
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Solution Overview
Problem
Existing light-emitting elements suffer from low efficiency of light extraction due to inadequate light reflection and adhesion issues between electrodes and functional layers.
Innovation Solution
A light-emitting element with a first electrode and a functional layer having a grain boundary surface roughness of 3 to 20 nm, featuring a light-reflective portion with crystal grains and pits to enhance adhesion and scatter light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a smooth surface is used between the electrode/functional layer and emission layer, then manufacturing is easier and adhesion is weaker, but light extraction efficiency is low due to insufficient scattering
Solution Approach 1:
The patent applies parameter changes by precisely controlling the surface roughness to fall within the specific range of 3 to 20 nm. This controlled roughness creates grain boundaries that act as scattering centers for light, improving light extraction efficiency without compromising manufacturing feasibility. The parameter optimization balances optical performance with manufacturability.
2Loss of energy
If the surface roughness is increased to enhance light scattering, then light extraction efficiency improves, but adhesion between layers deteriorates
Solution Approach 1:
The patent resolves this contradiction by identifying and controlling the optimal surface roughness parameter range of 3 to 20 nm. Within this range, the surface has sufficient irregularities to scatter light effectively while maintaining strong adhesion between layers. This precise parameter control ensures both optical performance and mechanical strength.
Solution Approach 2:
The patent applies local quality by creating grain boundaries with specific roughness characteristics in the light-reflective portion, while maintaining overall structural integrity. The localized surface irregularities at grain boundaries provide scattering centers without compromising the global adhesion strength of the layered structure.
3Loss of energy
If a light-reflective portion with grain boundaries is formed, then light scattering is enhanced, but the structure becomes more complex
Solution Approach 1:
The patent simplifies the structure by controlling the surface roughness parameter to naturally form grain boundaries during the manufacturing process. Rather than adding complex structural features, the invention uses parameter optimization of the existing surface to create the desired light scattering effect through grain boundaries with 3 to 20 nm roughness.
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
Improves light extraction efficiency by enhancing mechanical adhesion and scattering light through Rayleigh scattering, reducing detachment and maintaining electrical properties.
Implementation Method 1
scattering light through Rayleigh scattering
Data Source
AI summary
Provided is a first electrode, a second electrode, an emission layer positioned between the first electrode and the second electrode, and a functional layer positioned between the first electrode and the emission layer. At least one of the first electrode and the functional layer is a light-reflective portion having a grain boundary, and whose surface adjacent to the emission layer has an average roughness of 3 to 20 nm.