Substrate Surface Roughening via Selective Particle Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for roughening substrates, such as those used in light extraction layers for LEDs and solar cells, face challenges in achieving efficient light extraction while maintaining the flatness and reliability of thin film structures, particularly due to issues with adhesion and the size distribution of fine particles in light-scattering layers.
Innovation Solution
A method involving the application of a composition containing inorganic particles and an organic resin to a substrate, followed by selective etching using a solution that differentially etches the inorganic particles, creating a roughened surface with fine irregularities, thereby improving light extraction efficiency without compromising substrate flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light-scattering layer with fine particles is used to improve light extraction efficiency, then light scattering performance is improved, but the flatness of the light-emitting portion deteriorates
Solution Approach 1:
The light extraction layer is segmented into multiple layers: a lower light scattering layer with larger particles (5-20 μm) for primary light scattering, and an upper light scattering layer with smaller particles (1-5 μm) for fine-tuning light extraction. This segmentation allows each layer to perform its function optimally while maintaining overall flatness
Solution Approach 2:
Different regions of the light extraction layer have different particle size distributions and compositions. The lower layer has larger particles for strong scattering, while the upper layer has smaller particles for surface flatness. This local differentiation resolves the contradiction between scattering performance and flatness
2Illumination intensity
If the volume fraction of fine particles is increased to improve scattering performance, then light extraction efficiency is improved, but adhesion of the light-scattering layer deteriorates
Solution Approach 1:
The light scattering layer is formulated as a composite material containing inorganic fine particles (silica, alumina, titania, zirconia) dispersed in a transparent resin matrix. The composite structure provides both scattering performance and adhesion, with the resin matrix ensuring proper bonding to the light-emitting portion
Solution Approach 2:
The particle size distribution is carefully controlled within specific ranges (1-20 μm) and the volume fraction is optimized to balance scattering performance with adhesion. This parameter optimization ensures that high light extraction efficiency is achieved without compromising layer adhesion
3Illumination intensity
If conventional wet etching is used to roughen the substrate surface, then light extraction is improved, but control over etching uniformity and surface flatness deteriorates
Solution Approach 1:
A transparent resin layer is formed on the substrate surface before the light scattering layers. This resin layer serves as a protective and guiding layer during wet etching, ensuring uniform etching of the substrate while maintaining surface flatness. The preliminary action of forming this layer prevents direct uncontrolled etching
Solution Approach 2:
The transparent resin layer acts as an intermediary between the wet etching solution and the substrate. It controls the etching process by providing a uniform interface, ensuring that the substrate is etched evenly while the surface flatness is maintained. This intermediary layer resolves the contradiction between light extraction improvement and etching control
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 method effectively reduces light reflection and enhances light-emitting efficiency by forming fine irregularities on the substrate surface, improving the performance of light extraction layers in LEDs and solar cells without the adhesion issues associated with conventional methods.
Implementation Method 1
a second step of etching the substrate on which the organic resin layer (A) is formed by a solution containing hydrogen fluoride, hydrogen peroxide, or an acid, to roughen the surface of the substrate
Data Source
AI summary
A method for roughening a surface of a substrate, including: applying a composition containing inorganic particles and organic resin to the surface of the substrate and drying and curing the composition to form an organic resin layer; and etching the substrate by a solution containing hydrogen fluoride, hydrogen peroxide, or an acid, to roughen the surface. Preferably, the solution contains hydrogen fluoride and ammonium fluoride or hydrogen peroxide and ammonia, the resin layer contains a ratio of the particles to the resin of 5 to 50 parts by mass to 100 parts by mass, and the composition is a mixture of silica sol wherein silica is dispersed as the inorganic particles in organic solvent or titanium oxide sol wherein titanium oxide is dispersed, with a solution of the organic resin.