Directional Light Emission in a Single NaYF₄ Microcrystal via Photon Upconversion

Crystalline NaYF4 microstructures are harnessed to realize directional emissions by near infrared excitations through photon upconversion. By incorporating lanthanide ions of varying composition and concentration into the microcrystals, guided emissions of tunable colors (blue, green, and red) are achieved by near infrared excitations at diverse wavelengths (808−1532 nm). As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.