村井 俊介54Shunsuke MURAIナノアンテナ蛍光体における配光制御と高変換効率の両立（2021採択）Achieving light distribution control and high conversion efficiency in nanoantenna phosphors(Project 2021)51ure-eight-shaped macrocyclic molecule. By mimicking biosynthetic pathways and leveraging organic synthesis, we are developing a flexible approach to generate biologically relevant and functionally unique molecules at realistic costs.Ce3+ドープY3Al5O12(YAG:Ce)基板上にナノ粒子を周期的に配列したナノアンテナ蛍光体において，蛍光総量を落とすことなく前方放出光量を最大化することを試みた．まず，これまでのアルミニウムナノ粒子に替えて，TiO2ナノ粒子でナノアンテナを作製することで，蛍光総量，すなわち励起青色光から黄色蛍光への変換効率を落とすことなく前方放出量を向上させることに成功した．さらにTiO2ナノ粒子アレイが形成されたナノアンテナ蛍光体の裏面にSiO2とTiO2が交互に積層した多層膜を作製することで，後方に放出される黄色蛍光を反射し，前方への発光放出量を増加させることを試みた．(SiO2 /TiO2)ユニットの積層数が1層，3層での前方への発光増強はナノアンテナを有しないYAG:Ce基板に比べ，それぞれ11倍，18倍となった．6層においては発光増強は20倍まで増大した．また積分球を使った評価により，多層膜を付けても量子収率は1近くを維持することがわかった．前方方向への発光強度は大幅に高まったものの，まだ半分近い光が前方以外（裏面および端面方向）に放出されているので，今後の研究により，更なる指向性蛍光の増強を目指す．We attempted to maximize the amount of forward photoluminescence without reducing the total amount of luminescence in nanoantenna phosphors where nanoparticles are periodically arranged on a Ce3+-doped Y3Al5O12 (YAG:Ce) substrate. First, by fabricating a nanoantenna using TiO2 nanoparticles instead of the aluminum nanoparticles used in the first attempt, we were able to improve the amount of forward photolumi-nescence intenisty without reducing the total amount of luminescence, that is, the conversion efficiency from excitation blue light to yellow fluorescence. Then, we further attempted to increase the amount of forward photoluminescence from the nanoantenna phosphor by depositing a multilayer film consisting of SiO2 and TiO2 on the back side of it to reflect the photoluminescence radiated into the backward direction. Compared to the photoluminescence intensity from a YAG:Ce substrate without a nanoantenna nor multilayers, the en-hancement of forward photoluminescence intensity from the nanoantenna phosphors with one and three units of (SiO2/TiO2) layers were 11 and 18 times, respectively. With 6 layers the enhancement increased to 20 times. Also, evaluation using an integrating sphere showed that the quantum yield remained close to unity even with multilayers. Although the forward radiation is largely enhanced, nearly half of the photolumines-cence is still emitted to other directions (back and side), so future research will aim to harness more radiation into forward direction.
元のページ ../index.html#55