Asymmetric Microstructured LED Substrate for Light Extraction

The patent applies asymmetry by configuring the microstructured substrate with protruding elements having asymmetric cross-sections (e.g., triangular, trapezoidal, or rectangular with different side lengths) and asymmetric surface orientations. This asymmetric geometry creates multiple refraction paths for trapped light rays, increasing the probability that at least one path will satisfy Snell's law for light extraction. The asymmetric structure ensures that light rays incident from different angles experience different refraction behaviors, thereby improving overall light extraction efficiency compared to symmetric structures.

The patent introduces a new dimensional aspect by incorporating the obtuse angle parameter (≥90 degrees) in the cross-sectional geometry of the protruding microstructured elements. This angular dimension creates additional light extraction pathways that were not available in conventional structures. The obtuse angle configuration extends the effective extraction surface area and provides geometric pathways for light rays that would otherwise be trapped by total internal reflection, thereby addressing the energy loss issue through dimensional geometric optimization.

The patent employs parameter changes by optimizing specific geometric parameters of the microstructured substrate, particularly the obtuse angle (≥90 degrees) in the cross-section of protruding elements and the height-to-width ratio. These parameter optimizations enhance light extraction efficiency through improved refraction geometry while maintaining compatibility with conventional semiconductor fabrication processes. The parameter ranges are specifically selected to balance manufacturing feasibility with enhanced optical performance, allowing standard lithography and etching techniques to produce the required asymmetric structures.

The patent applies local quality by creating microstructured protruding elements with specific local geometric features (asymmetric cross-sections, obtuse angles) only at the substrate-light interface where light extraction is needed. The bulk substrate material and other LED components remain conventional, maintaining ease of manufacture. This localized structural modification concentrates the complexity only where it provides maximum optical benefit, while the rest of the device can be fabricated using standard, well-established processes.

The patent deliberately introduces asymmetry in the cross-sectional geometry of the protruding microstructured elements, using shapes such as triangles, trapezoids, or rectangles with unequal sides. This asymmetric design is specifically intended to improve light extraction efficiency by creating multiple refraction pathways. The asymmetric structures ensure that light rays incident from various angles experience different refraction behaviors, increasing the probability of successful light extraction compared to symmetric structures which provide uniform but limited refraction paths.

The patent adds a new dimensional parameter by incorporating obtuse angles (≥90 degrees) in the cross-sectional geometry of the protruding elements. This angular dimension creates additional geometric pathways for light extraction that are not available in conventional symmetric structures. The obtuse angle configuration extends the effective extraction surface area and provides multiple orientation paths for light rays, thereby improving light extraction efficiency through enhanced geometric diversity in the structural design.