微米结构材料中稀土发光性质的研究

Modern optical technologies, such as high-contrast displays, microlasers, and integrated photonics devices are highly dependent on the ability to manipulate light on the micrometer scale. However, efficient light-matter coupling on the microscale remains a huge technical challenge. In this regard, various luminescent microstructures capable of efficient absorbing excitation light and generating directional emission of tunable colors have been invented in recent years. Over the last decade, luminescent microrods and microdisks based on semiconductors, polymers, and assemblies of organic molecules, have been constructed for simultaneous use as gain media, resonance cavities, and waveguides. However, luminescent microstructures based on lanthanide ions have barely been exploited. In stark contrast with organic molecules and semiconductors, lanthanide luminescent materials exhibit sharp emission bands, long luminescent lifetimes, and large effective Stokes shifts, which are particularly suitable for use as a complement to polymers and semiconductors in lasing action and optical detection. Herein, we aim to integrate the excellent optical properties of lanthanide doped luminescent materials and highly structural designability of organic macromolecule for developing a new class of composite microstructures. We propose to employ lanthanide doped nanocrystals as optical medium and dope them into polymers with various compositions and morphologies (microrods, microtubes, and microdisks). A micromanipulator will be employed to provide mechanical stress and optical behavior of a single particle will be investigated with the assistance of an optical microscope. Once refined, we envisage that our study will significantly expand the scope of applications for lanthanide-based luminescent materials and open up new opportunities in diverse fields such as lasing and biological applications.

现代高端光学技术如高对比度显示器、微型激光器以及光子集成器件等都极大依赖于在微米尺度上控制光的转换和传播。然而在微米尺度下，如何有效地将光与物质相耦合是一项非常困难的挑战。为了解决这个问题，本项目拟发展一类含有发光组分的微米结构材料，利用其内部的电子跃迁有效吸收入射光，并产生颜色及传播方式都可随意调控的发射光。有别于以往的单组分发光系统，我们提议结合稀土发光材料的优异光学性能以及有机高分子材料的高度结构可设计性，开发一类新型复合微米结构材料，并系统研究其光学性质。我们计划以稀土掺杂纳米晶为发光介质，将其包埋于不同组成和形貌（如微米棒、微米管和微米盘）的聚合物微米结构中，并通过光学显微镜结合微操作机械手研究单个颗粒的发光行为及其对外部机械作用的响应。本课题一经完善，有望极大地拓宽稀土发光材料的应用范畴，并在激光及生物学等众多领域开创出新的机遇。

该项目旨在实现微米尺度上的可控发光，以应用于波导、激光、以及高性能的照明和显示等领域。我们成功合成了一系列镧系元素掺杂的微晶和由镧系元素掺杂的纳米晶体所组成的复合微结构，并在此基础上展示了一些新的发光现象，例如时间/空间可辨的多色发射和由机械力诱导的全光谱发光。据此，我们还展示了几类新型生物和光子器件应用，其中包括短波长激光器、防伪和光遗传学。特别地，我们发现了由负热膨胀诱导的发光增强现象，这一发现为克服光致发光的热淬灭提供了新的思路。在完成这个项目的过程中，我们在高影响力的期刊上共发表了23篇论文，其中包括J. Am. Chem. Soc., Angew. Chem.和Adv. Mater.等，另有两篇文章分别被Nat. Commun.和Chem. Rev.接收，即将发表。