染料敏化稀土上转换纳米晶的机理及性能优化研究

Recently, continuous efforts and attempts have been made to develop rare-earth upconversion nanocrystals in the field of fluorescence imaging, 3D volumetric displays, and anti-counterfeiting technology. Considering the practical applicability of such material, the central issue is focused on how to boost their upconversting luminescence intensity and efficiency. Here, this proposal aims at the improvement of upconverting performance by taking advantage of near-infrared (NIR) dye sensitization. This proposal will examine the key factors that influence the performance of dye sensitization, and further discuss the sensitization mechanism and upconversion dynamics involved. The detailed research contents include: (1) explore the influences of emitter concentration, rare-earth particle size, and dye concentration on the performance of dye sensitization, and elucidate the underlying mechanism; (2) evaluate the sensitization effect of two different types of sensitizers, i. e. NIR dye and rare-earth ion, and analyze the differences between their sensitization mechanisms; (3) optimize the composite system comprised of both dye and rare-earth sensitizers; (4) improve the stability of the dye-sensitized rare-earth nanocrystal composite system in aqueous phase. This proposal will provide theoretical support and technical guidance for the development of superior upconversion materials, and lay a solid foundation for advancing the practical applicability of rare-earth luminescent materials.

近年来，科研工作者对稀土上转换纳米晶在荧光成像、三维立体显示和防伪技术等方面的应用进行了大量的探讨。在面对该材料走向实际应用过程中，如何提升其发光强度和效率既是攻关关键，又是难关瓶颈。针对于此，本项目以提升稀土纳米晶的上转换发光性能为目标，通过近红外染料敏化的策略，实现上转换发光性能的巨大突破。本项目将详细研究影响染料敏化效果的关键因素，并深入讨论染料敏化机理和上转换动力学过程。具体研究内容包括：探明稀土发光中心掺杂浓度、纳米晶尺寸和染料浓度等因素对染料敏化效果的影响，并阐明其中的机理；评价染料和稀土两类不同敏化剂的敏化性能，对比分析两者敏化机理上的差异；探究染料和稀土双敏化剂协同敏化下，复合体系的优化制备；提高染料敏化稀土上转换纳米晶复合体系的水相稳定性。本项目将为研制高性能上转换发光材料提供理论支持和技术指导，为推进稀土发光材料的实用化进程奠定坚实的基础。

稀土上转换纳米材料在医学成像、生物检测及光伏等领域有着重大应用前景，如何提升其发光效率是其真正走向实际应用的关键问题。通过近红外染料敏化策略可解决稀土离子本身吸收截面窄的问题，从而极大提升稀土纳米晶的上转换发光性能。本项目研究并评价了有机染料和无机稀土离子两种类型敏化剂的敏化能力，从实验结果上证明了有机染料敏化增强稀土上转换发光的优势所在。本项目还对染料敏化稀土纳米晶体系下影响染料敏化效果的关键因素展开了系统性研究。通过对主基质选取、稀土敏化剂的掺杂浓度、纳米晶尺寸以及染料浓度等关键因素的研究，获得了染料敏化体系的最优实验参数，并且对实验规律做出了相应合理解释。根据上述所得的研究结论，我们最终建立了制备高性能上转换发光的染料-稀土纳米晶复合材料的实验条件和关键参数，并对该复合型材料的水相稳定性问题进行了研究。本项目的研究成果有望加速稀土上转换纳米发光材料实际应用的进程，实现我国稀土资源高值利用和产业链延伸。本项目执行期间，共表SCI论文6篇（4篇影响因子>5）。申请专利2项，其中1项已获授权。