Effectively infinite optical path-length created using a simple cubic photonic crystal for extreme light trapping

Frey Brian J., Kuang Ping, Mei-Li Hsieh, Jian-Hua Jiang, John Sajeev, Shawn Yu Lin

Research output: Contribution to journalArticle

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Abstract

A 900 nm thick TiO2 simple cubic photonic crystal with lattice constant 450 nm was fabricated and used to experimentally validate a newly-discovered mechanism for extreme light-bending. Absorption enhancement was observed extending 1-2 orders of magnitude over that of a reference TiO2 film. Several enhancement peaks in the region from 600-950 nm were identified, which far exceed both the ergodic fundamental limit and the limit based on surface-gratings, with some peaks exceeding 100 times enhancement. These results are attributed to radically sharp refraction where the optical path length approaches infinity due to the Poynting vector lying nearly parallel to the photonic crystal interface. The observed phenomena follow directly from the simple cubic symmetry of the photonic crystal, and can be achieved by integrating the light-trapping architecture into the absorbing volume. These results are not dependent on the material used, and can be applied to any future light trapping applications such as phosphor-converted white light generation, water-splitting, or thin-film solar cells, where increased response in areas of weak absorption is desired.
Original languageEnglish
Article number4171
JournalScientific Reports
Volume7
DOIs
StatePublished - 23 Jan 2017

Keywords

  • SILICON SOLAR-CELL; ARCHITECTURE; TECHNOLOGY; ABSORPTION; SCATTERING; LIMIT

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