上转换发光材料在照明、显示、光电转换、生物医药等方面具有广泛的应用前景，近年来引起了极大的关注。红光和近红外光被认为是生物组织的“光学窗口”，调节上转换纳米发光材料的发射波长使其落在“光学窗口”波段在生物医学应用上具有重要意义。为了优化上转换发光材料的性能及利用其特性开拓新的应用领域，国内外学者已逐渐将研究重点从单一材料转向复合材料。本项目拟利用碳点的荧光优势，选择合适的稀土掺杂氟化物上转换纳米材料和碳点，构建基于稀土掺杂氟化物与碳点的复合材料，研究复合材料的上转换发光性能，系统研究掺杂离子种类和浓度、组分类型、复合方式及激发光功率等对复合材料上转换发光的影响，揭示稀土掺杂氟化物与碳点之间的相互关系及能量传递机制，实现复合材料的上转换发光调控并获得增强的红光或近红外光上转换发射。该研究将有利于深入了解新型上转换发光材料的特性，为设计高效上转换发光材料提供理论和实验依据。

In recent years, upconversion materials have attracted tremendous attentions due to their various potential applications in lighting, display, photovoltaics, biomedicine, and so on. The red region and the near infrared (NIR) spectral range are considered as an “optical window” for biological tissues. Therefore, bringing the emission peaks of upconversion nanomaterials into the “optical window” is of significant importance for biomedical applications. To optimize properties of upconversion materials and develop their new applications, researchers have moved their research emphasis from single material to composites gradually. This project is designed to fabricate composites by appropriate rare earth doped fluorides and carbon dots because of the fluorescence advantages of carbon dots. The upconversion properties of the composites will be studied. The effects of doped-rare earth ions, component type, composited way and excitation power on the upconversion properties of composites will be investigated in detail. The relationship and energy transfer mechanism between fluorides and carbon dots will be disclosed. The fine tuning of upconversion emission will be realized and strong red and NIR upconversion emission will be achieved. This work will favor better understanding of properties of upconversion materials, providing theoretical and experimental basis for the fabrication of high-efficient upconversion materials.