高效稀土和钙钛矿量子点复合纳米材料上转换发光及其应用研究

Photon upconversion is a nonlinear optical phenomenon known as an anti-Stokes emission in which the sequential absorption of two or more low-energy photons leads to high-energy luminescent emission, and thereby have shown promising applications in areas as diverse as biological imaging, detection, therapeutics and full-color displays. However, it should be noted that most of the previous reports were mainly focused on the upconversion luminescence (UCL) in lanthanide ions doped inorganic materials, such unique UCL remains nearly untouched in other material systems especially for the newly emerging all-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) quantum dots. In this project, we will synthesize a series of high-quality hybrid UCL nanomaterials combined with the lanthanide-doped upconversion nanocrystals and all-inorganic cesium lead halide perovskite quantum dots (hereafter referred to as Ln-CsPbX3-UCNCs) to achieve highly efficient UCL of cesium lead halide perovskite quantum dots. The localized electronic energy level, excited state dynamics as well as upconversion luminescence efficiency for Ln-CsPbX3-UCNCs will be systematically studied by using the techniques like high-resolution temperature-change steady state/transient spectroscopy in an effort to clarify the UCL mechanism of in quantum dot Ln-CsPbX3-UCNCs Subsequently, one or two types of Ln-CsPbX3-UCNCs will be chosen as the photoelectric conversion material to fabricate multilayer-structured solar cells possessing a photoelectric transformation efficiency as high as 15%.

上转换发光是指吸收两个或两个以上低能光子而辐射一个高能光子的非线性发光现象，在多色发光显示以及荧光生物标记等领域已经显示了极好的应用前景。但目前的研究主要聚焦于稀土上转换发光，对其它材料体系特别是新兴的全无机钙钛矿量子点（CsPbX3, X = Cl, Br, I）上转换发光的研究几乎没有涉及。本项目拟以稀土和钙钛矿量子点复合上转换发光纳米材料（缩写为Ln-CsPbX3-UCNCs）为研究对象，在实现其可控制备的基础上，制备出具有高效量子点上转换发光的复合纳米材料数种。利用变温高分辨稳态-瞬态荧光光谱等手段，系统研究材料的电子能级结构、激发态动力学以及上转换发光效率与其内部微观结构等因素的构效关系，阐明实现高效量子点上转换发光的机理，并从中找出大幅提高其上转换发光效率的方法。在此基础上，构筑出高性能Ln-CsPbX3-UCNCs基多层结构太阳能电池，预期优选的器件光电转换效率大于15%。

在项目执行期间，项目组按照预期计划开展工作，重点开展了稀土和全无机钙钛矿量子点复合（Ln-CsPbX3-UCNCs）上转换发光纳米材料光的可控制备、结构性能调控、发光物理及其光电、光伏应用等研究，制备出了系列结构新颖、单分散、粒径小于100 纳米、具有高效稀土敏化的量子点上转换发光复合纳米材料；通过飞秒瞬态吸收、稳态变温高分辨光谱等先进谱学手段，实验确定了稀土离子和全无机钙钛矿领子点在该类材料中的精细电子能级结构电子能带结构和激发态寿命等关键的光谱学数据，并从中揭示复合纳米材料中量子点上转换发光效率与纳米颗粒微观结构、形貌、尺寸以及相态等因素的关系，阐明了稀土敏化的钙钛矿上转换发光机理，并建立提高其上转换发光效率的方法；在此基础上，项目组还发展基于Ln-CsPbX3-UCNCs复合上转换发光纳米材料的多层结构太阳能电池的制备技术，构建出具有高光电转换效率的Ln-CsPbX3-UCNCs 基太阳能电池，其光电转换效率大于21%，远超项目预设的目标效率（~15%）。在Adv. Mater., ACS Nano, Adv. Funct. Mater., Adv. Sci., CCS Chem.等专业期刊发表了高影响力SCI论文12篇，其中SCI一区论文6篇。申请或授权国内外发明专利7项（授权5项），其中一项中国发明专利《生物体内可降解上转换无机纳米材料及制备方法和应用》以80万元的价格技术转让。培养了研究无机发光材料的博士研究生4名，硕士研究生2名，顺利完成了预定的工作计划和研究目标。