Deep Black Surface Structure With Light-Trapping Rod Cavities

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Solution Overview

Problem

Existing methods for producing intensely black surfaces, such as those using carbon nanotubes on aluminum, are limited in their ability to achieve deep, intense, or subtle black colors and do not effectively trap light for enhanced absorption.

Innovation Solution

A manufacturing process involving directional solidification to grow a crystalline phase as aligned rods with a matrix phase between them, followed by selective removal of the matrix to form a comb-like structure with light-trapping cavities, using materials like aluminum and nickel alloys, and optionally including carbon or graphite, to achieve a black appearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If carbon nanotubes are grown on aluminum surface using CVD, then a black surface is obtained, but light trapping and absorption are not effectively enhanced

Engineering Contradiction:
Improvelight absorptionVSAvoidsurface structure
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The surface is segmented into numerous vertical rods or pillars that are evenly distributed across the substrate. This segmentation creates multiple light-trapping interfaces and increases the effective surface area for light absorption, resolving the contradiction by achieving enhanced light absorption without excessive structural complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention creates a porous-like structure with vertical rods separated by voids or spaces that trap light. This porous architecture increases light path length and absorption efficiency while maintaining a relatively simple overall structure, thus improving light absorption without proportionally increasing device complexity.

Inventive Principle:
Principle #31Porous materials

2Illumination intensity

If directional solidification is used to grow crystalline phase rods, then a comb-like structure with light-trapping cavities is formed, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvelight trappingVSAvoidmanufacturing process
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The invention utilizes phase transition during directional solidification to naturally form the rod-like crystalline structure. By controlling the solidification process from liquid to solid phase, the desired comb-like structure with light-trapping cavities emerges automatically, reducing the need for complex post-processing steps while achieving effective light trapping.

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The directional solidification process self-organizes the material into the desired rod-like structure with inherent light-trapping cavities. The system uses its own thermal gradients and phase change dynamics to create the functional structure, eliminating the need for additional complex manufacturing steps to form the light-trapping geometry.

Inventive Principle:
Principle #25Self-service

3Illumination intensity

If matrix material is removed between rods, then light absorption is enhanced, but material loss increases

Engineering Contradiction:
Improvelight absorptionVSAvoidmatrix material
Core Design Contradiction:
Illumination intensityVSLoss of substance

Solution Approach 1:

The invention selectively extracts or removes only the matrix material located between the crystalline rods, while preserving the rods themselves. This targeted extraction creates the light-trapping cavities necessary for enhanced absorption while minimizing overall material loss by maintaining the structural rods that provide mechanical integrity and optical function.

Inventive Principle:
Principle #2Taking out (Extraction)

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 process effectively creates a deep, intense black surface by absorbing light through the comb-like structure, enhancing color intensity and light trapping.

Implementation Method 1

The growth step corresponds to erecting or protruding the material in question along a principal direction... The growth stage is carried out by directional solidification, preferably thermal or by heating or cooling

Methodology Applied
Scientific EffectDirectional solidification: Freezing

Implementation Method 2

remove at least part of the matrix located between said rods... so as to form a comb-like material structure having rods and light-trapping cavities between said rods, so as to absorb light

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP4715076A1Method for producing a component having a deep black surface
Publication Date: 2026.03.25 THE SWATCH GRP RES & DEVELONMENT LTD
  • EP4715076A1 patent drawingFigure 1~2
  • EP4715076A1 patent drawingFigure 3~4
  • EP4715076A1 patent drawing

AI summary

One aspect of the invention relates to a method for manufacturing a black structure of a material (10) comprising at least two phases, of which at least one crystalline phase (1), and at least one other phase, called matrix (2), the method being characterized in that it comprises the following steps: - growing the material along a principal direction (Z) so that the at least one crystalline phase forms several rods aligned with each other and the matrix extends between the rods, - removing at least part of the matrix located between the rods of the at least one crystalline phase, - so as to form a comb-type material structure having rods and light-trapping cavities between said rods.