Light extraction efficiency of light-emitting diodes (LEDs) based on various photonic crystal (PhC) structures was investigated in this study. By using the plane wave method and the finite element method, the influence of several factors on the enhancement of light extraction was discussed, including lattice type, density of states from a photonic band diagram, ratio of cylinder radius and lattice constant, and thickness of a photonic crystal pattern. Some rules are given for the practical implementation of an optimized PhC-based LED with higher light extraction efficiency. In the simulation results, the maximum enhancement of the extraction efficiency could be found to be by a factor of approximately 2.8 for the optimized Archimedean tiling pattern in the LED device emitting at the center wavelength of 530 nm. However, with the use of optimized PhC structures, the square and triangular lattices reveal enhancements of ~1.7 and ~1.5, respectively. The extraction efficiency of the Archimedean PhC LED is much greater than that of the regular lattice PhC LED.
"Design and Modeling for Enhancement of Light Extraction in Light-Emitting Diodes with Archimedean Lattice Photonic Crystals," Progress In Electromagnetics Research B,
Vol. 11, 265-279, 2009. doi:10.2528/PIERB08112704
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